Final Report
Signal Control Strategies for Dual Left Turn Lanes
Submitted to: Centre for Transportation
Engineering & Planning (C-TEP) c/o Department of Civil Engineering University of Calgary 2500 University Drive N.W. Calgary AB T2N 1N4 Attention: Mr. Merv Clark, Executive Director
Submitted by: Earth Tech (Canada) Inc. Suite 300, 340 Midpark Way S.E. Calgary, Alberta T2X 1P1 Attention: Mr. Alf Guebert, P.Eng. Direct Line: 403-254-3377 Fax: 403-254-3333 E-mail: [email protected]
April 25, 2005 Project No. 60786
Table of Contents
SECTION TITLE PAGE NO.
Letter of Transmittal
1.0 INTRODUCTION...... 1 1.1 Background...... 1 1.2 Study Objectives...... 1 1.3 Report Organization...... 1 2.0 LITERATURE REVIEW...... 3 2.1 Background...... 3 2.2 Definitions ...... 3 2.3 General Research...... 4 2.4 Traffic Control Strategies ...... 9 2.5 Benefits and Detriments...... 14 2.6 Safety Issues for Traffic Control Strategies at MLTL...... 17 2.7 Driver Understanding of Traffic Controls Strategies...... 19 2.8 Literature Review Conclusion ...... 25 2.9 Literature Review Bibliography ...... 26 3.0 STATE OF THE PRACTICE...... 28 3.1 Introduction...... 28 3.2 Survey Design...... 28 3.3 Survey Results ...... 29 3.3.1 Inventory of Alternative Signal Phasing Locations ...... 29 3.3.2 Order of Phasing Implementation ...... 30 3.3.3 Dual Left Turn Phase Decision Warrants ...... 30 3.3.4 Criteria for Phasing Alternatives ...... 32 3.3.5 Signal Phasing Sequence...... 32 3.3.6 Collision Data...... 33 3.3.7 Signage for Dual Left Turns ...... 34 3.3.8 Signal Heads and Display Configuration for Dual Left Turns...... 35 3.3.9 Other Criteria for Signal Phasing for Dual Left Turns ...... 36 4.0 COLLISION ANALYSIS...... 37 4.1 Intersection Locations...... 37 4.2 Methodology...... 38 4.2.1 Collision Hazard Index...... 38 4.2.2 Capacity Analysis ...... 39 4.3 Capacity and Collision Analysis Results...... 39 4.4 Discussion of Results...... 39 5.0 COST-BENEFIT ANALYSIS...... 45 5.1 Scope of Analysis ...... 45 5.2 Quantification of Delay ...... 45 5.3 Quantification of Collisions...... 46 5.4 Examples...... 47 5.5 Application of the Cost-Benefit Tool ...... 50 6.0 CONCLUSIONS ...... 51
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SECTION TITLE PAGE NO.
Appendices: Appendix A: Dual Left Turn Survey Form Appendix B: City of Calgary Collision Analysis Appendix C: City of Edmonton Collision Analysis Appendix D: Hazard Index Ratio Calculations
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LIST OF FIGURES
FIGURE TITLE PAGE NO.
4.1 DUAL LEFT TURN HAZARD INDEX AND CONTROL DELAY...... 40 4.2 DUAL LEFT TURN HAZARD INDEX AND INTERSCTION DELAY...... 40 4.3 TUCSON, AZ PSEUDO-SLOTTED DUAL LEFT TURN BAY (PERMISSIVE PORTION OF PHASE) ...... 44 4.4 TUCSON, AZ PSEUDO-SLOTTED DUAL LEFT TURN BAY (PROTECTED PORTION OF PHASE) ...... 44 5.1 PROTECTED-PROHIBITED TO PROTECTED-PERMISSIVE ANALYSIS EXAMPLE ...... 48 5.2 PROTECTED-PERMISSIVE TO PROTECTED-PROHIBITED ANALYSIS EXAMPLE ...... 49
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LIST OF TABLES
TABLE TITLE PAGE NO.
3.1 PARTICIPATING AGENCIES ...... 28 3.2 INVENTORY OF ALTERNATIVE PHASING AND LEFT TURN TYPE ...... 29 3.3 PHASING IMPLEMENTATION SEQUENCE PREFERENCES...... 30 3.4 CRITERIA FOR APPLICATION OF SIGNAL PHASING OPTIONS FOR DUAL TURNS ...... 31 3.5 PHASING SEQUENCE PREFERENCES ...... 33 4.1 LOS CRITERIA FOR SIGNALIZED INTERSECTIONS ...... 39 4.2 SUMMARY OF CALGARY INTERSECTION ANALYSIS RESULTS...... 41 4.3 SUMMARY OF EDMONTON INTERSECTION ANALYSIS RESULTS...... 42 5.1 AFTERNOON PEAK HOUR TO DAILY DELAY SAVINGS FOR THE TOTAL INTERSECTION...... 45
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1.0 INTRODUCTION
1.1 BACKGROUND
Increased traffic volumes on urban arterial roadway networks has resulted in the provision of dual left turn lanes to maintain acceptable levels of service at intersections. This practice has become commonplace in larger and mid-sized cities across Canada. Within Alberta, there appears to be two differing philosophies for the implementation of signalized traffic control to accommodate dual left turn lanes.
The City of Edmonton allows dual left turns to occur as a permissive movement. Where a potential safety concern has arisen, however, the City has restricted dual left turns to a protected-prohibited phase movement only. Because their philosophy towards dual left turn traffic is still evolving, the City of Edmonton has expressed interest in developing a warrant to determine when to implement protected-prohibited dual left turn movements.
The City of Calgary has a warrant to define if protected or permissive movements should be used for dual left turns. Because there is a perception that the warrant often restricts dual left turns to protected-prohibited movements only, the city generally only allows implementation of protected-prohibited dual left turns. Under limited circumstances, a review of the City’s warrant may result in some acceptable recommendations for adjustment, including permissive phasing.
1.2 STUDY OBJECTIVES
The objectives of this study are to:
‹ Understand the range of signal control strategies for dual left turn lanes currently used across Canada, how they were developed, and how they are implemented. ‹ Understand the benefits and detriments of the different signal control strategies currently used by the City of Edmonton and the City of Calgary.
‹ Identify, if possible, a strategy balancing the potentially conflicting desires to minimize traffic delays and provide for safe traffic operations.
1.3 REPORT ORGANIZATION
A literature search was undertaken to identify and document any research done on traffic control strategies for dual left turn lanes. The results of this review are documented in Section 2.0.
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Earth Tech conducted a survey of Canadian agencies to identify and document the traffic control strategies for dual left turn lanes throughout the country. A description of any warrants related to traffic control for dual left turns that have been developed by agencies was requested in the survey, as well as questions about any safety analysis done on dual left turn situations within their jurisdiction. The results of the survey are discussed in Section 3.0.
The project team collected and analyzed traffic and collision data for intersections in Calgary and Edmonton that use differing left turn control strategies. This data, which is presented in Section 4.0, was analyzed to define any correlation between collision rates, capacity, and the left turn strategy employed.
Section 5.0 addresses the question of balancing efficiency (minimizing delay) versus safety (reducing collisions) through a suggested cost/benefit analysis method. Sample calculations are included to outline the application of the method.
Concluding recommendations and direction for strategy development are offered in Section 6.0.
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2.0 LITERATURE REVIEW
2.1 BACKGROUND
The project team undertook a literature search to identify and document any research done on traffic control strategies for dual left turn lanes. In order to complete this review, Earth Tech extensively reviewed Dialog Databases [NTIS, Compendex and TRIS (Transportation Research Information System)], the Institute of Transportation Engineers Digital Library, and Earth Tech's private library collection. As well, a number of general interest searches were completed.
While the literature search focused primarily on traffic control strategies for dual left turn lanes, the review considered a number of articles that dealt only with single left turn lanes. This information has been included when it is considered to be relevant to the literature search.
2.2 DEFINITIONS
There is a variety of terminology that is used for determining traffic signal control strategies. As a result, this report has attempted to standardize the terminology used for signal phasing.
Some of the following definitions were taken from a paper which was presented at the 69th Annual Conference, Institute of Transportation Engineers (1999) 1:
‹ Permissive Left Turn: The left turning vehicles are permitted to turn during the normal green ball display for through traffic and can complete the turn if adequate gaps occur in opposing traffic. The left turning vehicles must yield to the opposing traffic and pedestrians legally crossing the roadway.
‹ Protected-Permissive (Leading) Left Turn: The left turning vehicle is first given a protected interval to turn left during the display of a green arrow, and then permitted to turn when adequate gaps appear in the opposing traffic during the display of a circular green. A four-section or a five-section signal head, with left turn arrow indications as well as circular indications, is used. ‹ Permissive-Protected (Lagging) Left Turn: The left turning vehicles are first permitted to make a left turn when adequate gaps appear in the opposing traffic during the display of a circular green then protected to turn left during the display of a green arrow. A four-section, or a five-section, signal head, with left turn arrow indications as well as circular indications, is used.
1 Koupai, Parvis A. and Amit M. Kothair; "Recommended Guidelines for Protected/Permissive Left-Turn Phasing"; Proceedings; 69th Annual Conference; Institute of Transportation Engineers (1999); p.25.
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‹ Protected-Prohibited Left Turn: This phasing provides left turning vehicles with their own separate left turn arrow indications and no conflicting movements are allowed. The left turn movement is terminated with its own clearance display and is not permitted to proceed when the opposing traffic is given a green indication. ‹ Trap: A "trap" situation happens when the through traffic in both directions does not terminate at the same time. Vehicles in the left turn lane, seeing a circular yellow indication, tend to assume that the opposing through traffic is also terminating and make a left turn unprotected at the beginning of the yellow ball indicated, but end up colliding with the oncoming vehicle.
‹ DALLAS2: Dallas phasing is a modified leading or lagging, protected-permissive sequence. When one of the left turns is protected, and its adjacent through movements plus right turns are displayed as a circular green signal, the opposing left turn is permitted (i.e. shown the green circular). The throughs and rights adjacent to the permissive left are shown a red signal (because the opposing left is permissive). Dallas phasing leads to a unique display: circular green in a five-section head for the lefts, indicating permissive (not protected) turning, and circular red for the throughs plus rights. The five-section head is required for the lefts since Dallas phasing provides for both protected and permissive left turns. Drivers claim they understand this phasing as well as, or better than, they understand other types of left turn phasing. Dallas phasing provides the advantage of true protected-permissive, leading/lagging operation without the yellow trap.
‹ Exclusive Left Turn Lanes (EXLTL): This is the situation where the left turn lanes are used only for left turn movements. ‹ Shared Left Turn Lanes (SHLTL): This is the situation where one of the lanes is a shared with the left turn and through movements. ‹ Multiple Left Turn Lanes (MLTL): Any situation where there is more than a single left turn lane for the same movement.
2.3 GENERAL RESEARCH
The literature search has revealed a number of agencies and associations that have undertaken studies on dual left turn lanes. In addition to discussions on traffic control strategies for dual left turn lanes, these studies address when dual left turn lanes should be implemented, and the capacity and design of the lane cross-section. While not specific to the application of traffic control strategies, a summary of the general research is included for information purposes, and to illustrate the need to first determine if the application of a dual left turn lane configuration is appropriate.
2 Asante, Seth A., Siamak A. Ardekani, and James C. Williams; “Selection Criteria for Left Turn Phasing and Indication Sequence”; Transportation Research Record 1421; Transportation Research Board; 1993.
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In 1987 Wortman3 completed a study on the capacity of dual left turn lanes for the Arizona Department of Transportation. Based on available literature at that time, he found that the research studies that had been conducted previously yielded considerable variability and limited understanding of dual left turn lanes.
While there was some variation in the application and use of dual left turn lanes in terms of design and traffic control, the applications generally involve exclusive turn lanes and protected signal phases even though other operational configurations and traffic control may be found in Arizona and throughout the United States. The rationale for using dual left turn lanes is generally associated with capacity, left turn storage, and intersection operation. The "rule-of- thumb" guideline that appears throughout the literature suggests the consideration of dual left turn lanes if the left turn volume exceeds 300 vehicles per hour (vph). As well, research studies have primarily focused on exclusive dual left turn lanes with protected signal phases. The capacity procedures are generally limited to these conditions.
The ITE Technical Council Committees 5P-5 and 5S-14 also suggests that the use of exclusive dual turn lanes may be considered when design volumes indicate left turning traffic will be at least 300 vehicles per hour. They caution, however, that further studies should be made to assess the overall benefits and costs of using a multiple left turn lanes (MLTL).
Many geometric elements of a turn lane installation are defined by parameters that have no relation to whether single or dual left turn lanes are used. Examples of such independently- determined elements are painted versus raised medians, lane widths on the approach and departure, straight-tapers versus reverse curves to introduce the turn lanes, and minimum design turning radii.
Several conclusions regarding current practices and experience with MLTL’s were surmised in a report entitled “Capacities of Multiple Left Turn Lanes”. This report was prepared by the ITE Technical Council Committee SP-55 based on subcommittee interviews with 25 agencies. It was found that the majority of agencies followed these guidelines for operating MLTL’s:
‹ Leading protected-prohibited green phasing with no conflicting pedestrians allowed,
‹ Special markings to delineate the common limit between the inner and outer turning vehicle paths, and ‹ Turn-lane designations indicated by overhead signs, sometimes supplemented by ground-mounted signs.
3 Wortman, Robert H.; “Capacity of Dual Left Turn Lanes: State of the Art”; Report Number FHWA-AZ87-820; Peter A. Mayer & Associates; prepared for Arizona Department of Transportation; Published by National Technical Information Service, U.S. Department of Commerce; 1987; p.25. 4 ITE Technical Council Committees 5P-5 and 5S-1 (1995); “Capacities of Double and Triple Left Turn Lanes”; Compendium of Technical Papers; Institute of Transportation Engineers; 1995; pp.209-213. 5 ITE Technical Council Committee 5P-5; “Technical Council Report Summary: Capacities of Multiple Left Turn Lanes”; ITE Journal; Institute of Transportation Engineers; September 1993; p.31.
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According to this committee’s findings, the agencies interviewed have experienced no significant opposition to the use of MLTL’s. Minor objections have related to the use of protected-prohibited phasing only. Most agencies do not hesitate to use a dual left turn facility where such an installation would be cost-effective and compatible with other intersection conditions.
Based on Wortman's2 findings, the recommended practice is that a left turn volume of 300 vph or more merits consideration of dual left turn lanes. The decision to use dual turn lanes should be evaluated based on the conditions at a specific intersection site. Intersection and turn lane capacity, as well as turn lane storage, are important considerations.
In their Traffic Control Signal Design Manual6, the Connecticut Department of Transportation provides guidelines for the use of MLTL’s. The manual states that dual turning lanes, either on two exclusive lanes or on one exclusive lane and a second shared lane, should be considered when:
‹ There is not sufficient space to provide the calculated length of a single turn lane, ‹ The calculated length of a single turn lane becomes prohibitive,
‹ The necessary time for a protected left turn phase becomes unattainable to meet the level-of-service criteria (average delay per vehicle), or ‹ The volume to capacity ratio is greater than or equal to 0.90.
The manual suggests that a dual left or right turn lane onto an expressway entrance ramp should be discouraged.
A dual turn lane (both lanes exclusive) can potentially discharge approximately 1.9 times the number of cars which will discharge from a single exclusive turn lane. However, to work properly, several design elements must be carefully considered:
‹ Throat width: Because of off-tracking characteristics of turning vehicles, the normal width of two travel lanes may be inadequate to properly receive two vehicles turning abreast. ‹ Widening approach through lanes: If a 9 m (30 ft) or 11 m (36 ft) throat width is provided to receive dual turn lanes, the designer should also consider how this will affect the through traffic approach from the other side. ‹ Special pavement markings: These can effectively guide two lines of vehicles turning abreast. The guide markings are terminated when sufficient guidance is provided.
6 Connecticut Department of Transportation; “Traffic Engineering”; Traffic Control Signal Design Manual; Available: http://www.dot.state.ct.us/bureau/eh/ehen/traffic/manual/mainindex.htm
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‹ Signal indications: Dual turn lanes provide for major traffic movements and require two signal heads. ‹ Opposing Left Turn Traffic: If they are simultaneous, opposing left turns will be allowed. The designer should ensure that there is sufficient lateral clearance for all turning movements. ‹ Turning templates: All intersection design elements for dual turn lanes must be checked by using the applicable turning templates.
According to the ITE Technical Council Committees 5P-5 and 5S-17:
‹ The total required storage capacity for a MLTL is typically calculated using one of the many methods currently employed to derive the needed length of single left turn lanes. ‹ In situations where opposing left turns are run concurrently with a MLTL, there is little agreement on the minimum spacing that should be provided between the outer turning path limits of opposing vehicles. Most agencies determine the minimum separation on a case-by-case basis.
‹ The majority of the agencies interviewed use the following guidelines for operating MLTLs: o Leading, protected-prohibited phasing with no conflicting pedestrians allowed, o Special markings to delineate the common limit between the inner and outer turning vehicle paths, and o Turn lane designations indicated by overhead signs, sometimes supplemented by ground mounted signs. ‹ None of the interviewed agencies had completed special studies to derive local saturation flow rates for MLTLs.
Based on information from the Florida Section of ITE, Billingsley8 agreed with others in that protected-prohibited left turn phasing should be provided for an intersection approach if any of the following conditions exist:
‹ Dual left turn only lanes are operating, ‹ Intersection geometrics force the traffic engineer to provide the left turn driver with an exclusive signal head that cannot be shared with adjacent through lanes,
‹ Sight distances to opposing traffic are less than 250 feet (76m) when the opposing traffic is traveling at 35 m.p.h. (60 km/h) or less than 400 feet (122m) when the opposing traffic is traveling at 40 m.p.h. (70 km/h) or more. This represents
7 ITE Technical Council Committees 5P-5 and 5S-1 (1995). 8 Billingsley, Lee E. et al.; "Left Turn Phase Design in Florida"; From the Florida Section ITE; ITE Journal; September 1982; p.28-35.
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approximately five seconds of travel time which was the first gap size universally accepted by all left turn drivers in the California research project, or ‹ The approach is the lead portion of a lead/lag intersection phasing sequence.
Guidelines for Left Turn Treatment in the State of Florida9 concur that protected-prohibited left turn phasing shall be provided for an intersection approach if dual left turn only lanes are provided.
The efficiency of dual left turn lane intersections with protected-prohibited left turn signal phases were studied in Charlotte, NC.10 The Charlotte research looked at studies over the previous 25 years that have shown that left turn movement capacity can be increased by an average of 80 percent during peak hours, when a dual left turn lane is installed on a high volume left turn approach. By increasing the capacity of movement for one approach, and by allowing more vehicles to traverse the intersection within a given length of green time, average vehicle delay is reduced. When this extra time is allocated to other lane movements, delay is reduced for the entire intersection.
The Charlotte study concluded that dual left turn movements can more efficiency accommodate large volumes of left turn traffic. Properly applied, this technique can reduce delays at signalized intersections. It was concluded from the results that the decrease in overall intersection delay ranged from 6 percent to 37 percent by using dual left turn lanes in place of a single left turn lane with proportionately more green time. The results of the analyses indicate that the installation of dual left turn lanes is favourable in intersections containing high volumes of left turning traffic and opposing traffic. The dual left turn lane installation resulted in decreasing delay by an average of 23 percent from the previous single left turn lane configuration.
As part of a larger study directed at estimating the saturation flows of exclusive dual left turn lanes, Stokes, et al11, described their findings in an article published in the ITE Journal. These findings are based on a total of 3,458 completed left turns from exclusive dual left turn lanes on 14 intersection approaches in three Texas cities. Results of their findings indicated:
‹ The observed turn volumes were approximately equally distributed between the two lanes of dual left turn movements studied, ‹ The average number of left turns on amber and red tended to increase as average left turn green time decreased,
9 “Guidelines for Left Turn Treatment”; Traffic Engineering Manual; Signals; Florida; Available: http://wwwll.myflorida.com/traffic 10 Shaik, Riya A. and Johnny R. Graham; "Efficiency of Dual Left Turn Lane Intersections in Charlotte, A Study Using TRAF-NETSIM", ITE Journal, April 1996; pp.26-33. 11 Stokes, Robert W., Caroll J. Messer, and Vergil G. Stover; “Left Turns on Amber and Red from Exclusive Double Left Turn Lanes”; ITE Journal; Institute of Transportation Engineers; January 1986; pp.50-53.
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‹ The average number of left turns on red tended to increase with the average number of left turns on amber, ‹ The average drivers in lane 2 (the outside lane) made fewer left turns on red than drivers in lane 1 (the inside lane), particularly when the left turn green time was relatively short, and ‹ The average number of left turns on amber and red suggest that for saturated cycles with relatively short green times (e.g. about 10 seconds), one could expect about 4 vehicles/cycle to enter the intersection from the two lanes combined after the end of the actual green period.
Exclusive dual left turn lanes are defined as two continuous lanes of an intersection approach that are designed solely for left turning vehicles and are protected from opposing through and cross traffic with separate signal phasing.
In a 1991 field survey completed by NCHRP12 it was determined that engineers use traditional methods to determine the number of left turn lanes at a Single Point Urban Interchange (SPUI). The methods used in determining the number of lanes were based primarily on forecasted traffic demands, although there is also a predisposition among traffic engineers to provide dual lanes at all high-type intersections and interchanges whenever possible. This attitude is even more applicable to the SPUI because of the difficulty in modifying its design elements once constructed. Most SPUI designers prefer dual left turns for the traffic conditions served. The added turn lanes provide additional signal flexibility and a significant increase in interchange capacity with some modest increase in signal clearance times.
2.4 TRAFFIC CONTROL STRATEGIES
While the use of dual left turn lanes to increase capacity and improve traffic control is becoming increasingly common, there appears to be no consistency in the application of traffic control strategies to enhance vehicular movement and ensure driver safety.
The Florida Section of ITE5 suggests the following configuration for selecting the type of left turn signal display using protected-prohibited left turn phasing:
‹ For dual left turn lane situations, the choice is between using a single 3-section vertical head, two 3-section vertical heads, or a single 4-section cluster. The degree of hazard created by circular red burnout is the deciding factor and sub-committee members could not reach an agreement on a recommendation for this situation. Some subcommittee members felt strongly that two 3-section vertical heads should always be provided for dual left turn lanes. Other subcommittee members felt
12 National Cooperative Highway Research Program Report 345; “Single Point Urban Interchange Design and Operations Analysis”; Transportation Research Board; December 1991; p.15. 5 Billingsley (1982); pp.28-35.
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strongly that the temporary period of circular red vertical head would not be hazardous enough to warrant a recommendation to always provide two 3-section vertical heads. Specification of a standard signal display for dual left turn lanes is recommended as a subject for future research. ‹ The protected-prohibited left turn signal head should be located over the centre of a single left turn lane. If two left turn signal heads are used for dual left turn lanes, they should be located over the centre of each left turn lane. If a single left turn signal head is used for dual left turn lanes, it should be located over the lane line separating the two left turn lanes.
‹ Protected-prohibited left turn phasing, with dual left turn lanes – a single 3-section vertical signal head (from top to bottom – circular red, circular yellow, left turn green arrow) should be centered over the lane line in between the left turn lanes; or two 3-section vertical signal heads should be used, with one centered over each left turn lane. A supplemental sign having the legend “LEFT TURN SIGNAL” or “LEFT TURN ONLY” should be located next to each left turn signal head.
According to an analysis by the NCHRP13, for a SPUI, the choice of signal phasing sequence for a particular intersection is dependent on many factors:
‹ When left turn volume or left turn related collisions are relatively high, protected- prohibited left turn phases are often added at high-type intersections. ‹ The number and sequencing of left turn phases depend on the desired left turn operation and potential impact that a protected-prohibited left turn phase may have on other movements. ‹ If a protected-prohibited left turn phase is included, it can occur before (leading) or after (lagging) the through movement.
The NCHRP study also identified the conditions under which protected-permissive phasing should not be considered:
‹ Movement speeds on the opposing through road are over 45 m.p.h.
‹ More than two opposing through lanes to cross (because of the large gap between through vehicles needed by the left turn driver to clear the extended conflict area. ‹ Dual left turn movements (because of adverse interaction between left turn vehicles in adjacent lanes and restricted sight distance).
As part of the NCHRP analysis, agencies contacted indicated that protected-permissive left turn phasing was not a feasible option, and that all SPUI’s surveyed had protected-prohibited left turn phasing for both the cross road and off-ramp left turn movements. Two agencies
13 NCHRP Report 345
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offered additional insight. One had considered using protected-permissive phasing but noted that the left turn driver, attempting a permissive manoeuvre, would not be able to see the left turn signals if their mounting location was on the bridge fascia relatively near the stop line (typical of SPUIs). This necessitated a supplemental left turn signal. The second agency had used protected-permissive phasing for a brief period but reverted to protected-prohibited after experiencing a significant number of left turn collisions.
Members of the Colorado/Wyoming Section of ITE14 also conducted a study to examine the use of permissive dual left turn phasing at signalized intersections. The purpose of the study was to determine if permissive dual left turn movements experienced reasonable collision rates, as compared with protected-prohibited dual left turns, and with single left turns. Committee members conducted a telephone survey of the 50 State Departments of Transportation (DOT) and the District of Columbia, in order to gain information on the use of permissive dual left turns on a nation-wide basis. Responses from 45 states, plus the District of Columbia, were received. The results of this survey indicated:
‹ 14 of the 46 survey respondents (30%) operate permissive dual left turns at one or more signals all using protected-permissive phasing. These 14 agencies are Colorado, Delaware, District of Columbia, Georgia, Hawaii, Montana, New Mexico, Maine, Maryland, Mississippi, Ohio, Rhode Island, West Virginia, and Wyoming.
‹ Other agencies had tried protected-permissive phasing but discontinued its use due to safety concerns. The committee was unable to obtain any written agency policies regarding the use of permissive dual left turns, although many agencies indicated that directives have been issued addressing this issue. ‹ State DOT’s that do not use permissive dual lefts generally identified safety concerns related to intersection sight distance and geometrics as the reasons why this phasing wasn’t used. States that do use permissive dual lefts cited increased intersection capacity as the deciding factor. Other factors for consideration, mentioned by surveyed agencies, included opposing traffic volumes, collision experience, heavy vehicle traffic, and weather. Some of the survey respondents indicated that municipalities within their state were taking the lead in using protected-permissive phasing dual left turns. Municipalities mentioned by the respondents were: Tucson, AZ; Aurora; CO; Boulder, CO; Colorado Springs, CO; Denver, CO; Lakewood, CO; Westminster, CO; Columbia, OH; Nashville, TN; and Dallas, TX.
The committee concluded from this survey that, while dual left turns are not used frequently by most agencies, a significant number of agencies are using them. Written policies governing the use of permissive dual lefts are sparse and the use of this phasing is not localized to one geographical area.
14 Carnahan, Chris R. et al.; "Permissive Double Left Turns: Are They Safe?"; Traffic Signal Committee of the Colorado/Wyoming Section of ITE; 1995.
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Potential problems with permissive dual left turn movements included:
‹ Sight distance: Because the driver of a left turning vehicle may not be able to see conflicting traffic due to adjacent or opposing left turning vehicles,
‹ Increased number of conflicts, and ‹ Driver judgment.
In an analysis of previous studies completed in Florida, Maryland, California, Virginia, and Arizona, Koupai15 concluded that, while protected-permissive phasing provides for reduction in delay compared to protected-prohibited phasing, protected-permissive phasing creates an increased collision potential and should not be used when a number of conditions, including multiple left turn lanes exist on the approach. Based on a questionnaire survey conducted by Koupai, with 117 respondents including 8 from Canada, it was determined protected- permissive left turn phasing is widely used to increase the intersection capacity, especially by cities in California and Canada. A permissive-protected (lagging) phase is used to improve the progression in coordinated systems where the opposing left turn is prohibited, fully protected, or at a "T" intersection. Koupai also determined that 37 agencies had warrants in place for situations where there was more than one left turn lane.
Koupai's proposed guidelines are divided into three groups: conditions, minimum requirements and suggested guidelines. If any one of the conditions is not met, even though some or all of the requirements are satisfied, protected-permissive left turn phasing should not be used. One of conditions cited indicates that there should not be more than one left turn lane, unless the dual left lanes can be made safely with adequate sight-distance for turning vehicles. Protected-permissive left turn phasing should be considered only if all conditions, and at least one of the requirements, are met.
Koupai recommends the following guidelines for using protected-permissive phasing:
‹ Left turning traffic should not have a separate signal head. A "shared" signal head for both through and left turning traffic may be generally located on mast-arm above the line separating the left turn lane from the adjacent through lane, or above the middle of the number one lane. Median mounted signal head is also acceptable. ‹ Lens arrangements having five heads (cluster head on mast-arm or spanwire) (not a Canadian Standard), may be used for protected-permissive (leading) and permissive- protected (lagging) phasing. A separate GREEN arrow and YELLOW arrow for left turns must be used. Caution should be taken with the use of the fibre optic green arrow/amber arrow signal section. Colour-blind drivers may not be able to distinguish the change from green arrow to amber arrow in these sections. Note is made that some agencies in the United States and Canada do not support this proposed lens arrangement and use of arrows.
15 Koupai (1999); p.25.
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‹ Special regulatory signs, 1988 Manual for Uniform Traffic Control Devices (MUTCD) R10-12 may be used in the following situations:
o During the transition period when changing from protected-prohibited to protected-permissive phasing, o When signal head placement is such that the driver may not otherwise understand the meaning of the green ball, or
o Where collision or traffic-conflict experience indicates a problem with compliance.
In “Guidelines for the Use of Protected-Permissive Left Turn Phasing”, Agent16 concurs that warrants should be used to determine the need for a left turn phase. These warrants include collision experience, delay, volumes, and traffic conflicts. Warrants for collision experience and traffic conflicts indicate a collision problem for which protected-prohibited phasing is appropriate. Agent indicates that, while the time saved makes protected-permissive the preferable method of left turn phasing when compared with protected-prohibited phasing, it should not be used when there are dual left turn lanes on the approach.
The Connecticut Department of Transportation17 also provides guidelines for left turn phasing. Their Traffic Control Signal Design Manual defines the simplest and most common type of phasing as a two-phase operation, with a phase for main line traffic and another phase for the cross street. In this two-phase sequence, the major crossing through movements are separated, but the left turn movements must yield to opposing traffic, turning only when there is an adequate gap in the opposing traffic. The next most common added phasing is for left turn, and then for pedestrian traffic. More intersectional problems are caused by left turning traffic than any other vehicular movement.
Basic sequences used to accommodate left turn movements are as follows:
‹ Advance green (protected-permissive): Left turning vehicles, from a single approach only, are allowed to move together with the through traffic on that approach, while the opposing traffic is stopped and then permitted to move on the arterial phase which follows. The protected left turn portion of the phase is terminated through the display of a yellow arrow and a circular green simultaneously. The advance can be either fixed time or actuated. Can be used with or without an exclusive left turn lane.
‹ Permissive-protected (lagging): This phasing does not require an exclusive left turn lane to implement. A permissive-protected lag green is terminated with the display
16 Agent, Kenneth R.; "Guidelines for the Use of Protected/Permissive Left Turn Phasing", ITE Journal; July 1987; pp.37-42. 17 Traffic Engineering: Traffic Control Signal Design Manual; Connecticut Department of Transportation; Available: http://www.dot.state.ct.us/bureau/eh/ehen/traffic/manual/mainindex.htm
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of a circular yellow, followed by circular red. Advantages associated with permissive-protected (lagging) phasing are that:
o Both directions of straight through traffic start at the same time, o Approximates the normal driving behaviour of vehicle operators with the execution of the left turn movement in gaps at the end of the through movement phase for the lag direction, o Provides for vehicle/pedestrian separation as pedestrians normally cross at the beginning of the straight through green interval. Where pedestrians are crossing the side street concurrently, the pedestrian clearance has been completed prior to the beginning of the lagging-green interval, o Left turns do not pre-empt the right-of-way from the opposing straight through traffic movement and takes advantage of increased headway after the initial phase queue passes, o If the signal is coordinated for through traffic, it is also coordinated for left turn traffic. Coordinated systems with all leading lefts may have a tendency for traffic to arrive at the left turn signal just as it turns yellow, and o Cuts off only the platoon stragglers from adjacent signalized interconnected intersections.
‹ Lagging left turns normally will not be used if oncoming traffic has any one of the following types of left turn treatments: permissive, leading protected-permissive, or lagging permissive-protected with a different split for the opposing left turn.
‹ Directional Separation: It has become necessary at times to separate side street phases at certain offset side streets or where heavy left turns are encountered, moving all traffic on one side street, then totally stopping that traffic and letting the other side street move on an exclusive, protected phase. When this type of phasing is selected, a circular green with left turn arrow is to be displayed on the left most signal face. ‹ Quad: The opposing left turns start simultaneously as a dual advance.
2.5 BENEFITS AND DETRIMENTS
According to the ITE Technical Council Committees 5P-5 and 5S-118, and assuming dual turning paths are adequately delineated, the collision rate of dual turn lanes appear to be similar to a single turn lane, if the two types of installations are operated with the same phasing logic. The agencies interviewed have experienced no significant opposition to the use of MLTLs. Minor objections have related to the use of protected-prohibited phasing, which eliminates possible benefits of employing permissive phasing during non-peak flow periods.
18 ITE Technical Council Committees 5P-5 and 5S-1; 1995.
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These findings differ from those reported by the Colorado/Wyoming Section of ITE19 whose findings indicate there are a number of potential problems with permissive dual left turn movements. These concerns include:
‹ Sight distance: The driver of a left turning vehicle may not be able to see conflicting traffic due to adjacent or opposing left turning vehicles, ‹ Increased number of conflicts, potentially resulting in an increased number of conflicts due to sideswipe collisions, and ‹ Driver judgment: It can be difficult for motorists to judge the gaps in conflicting traffic due to the number of conflicting lanes of traffic and the speed of the oncoming traffic.
As part of their survey, the Colorado/Wyoming Section of ITE contacted the ITE Technical Council Committee 4A-30 – Warrants for Permissive-Protected Left Turn Phase. While there is a lack of consensus, the preliminary recommendation emerging from that effort is that permissive dual left turn phasing not be used.
Left turn collision rates, from all jurisdictions were compared by type of left turn phasing and number of turn lanes with the following results:
‹ Protected-prohibited phasing results in the lowest collision rates (as expected) with no appreciable difference between single or dual left turns
‹ Collision rates with permissive phasing (permissive or protected-permissive) were substantially higher for dual lefts than for single lefts, although in all cases the rates were less than 1.0 collision per million entering vehicles (MEV)
‹ Dual left turn collision rates increased with the number of opposing approach lanes crossed ‹ Dual left turn collision rate did not show a direct correlation with opposing approach speed limits
Changing the dual left turn phasing from protected-permissive to protected-prohibited during the afternoon peak hour, resulted in an increased the delay for each turning approach by an average of 131 percent and the left turning approach fuel consumption increased by an average of 38 percent. Also, because of the signal time allocation adjustments required by the change in phasing, the average delay for opposing movements was increased by an average of 10 percent, and the fuel consumption was increased by an average of more than 5 percent.
19 Traffic Signal Technical Committee of the Colorado/Wyoming Section of ITE; “Permissive Double Left Turns: Are They Safe?”; Institute of Transportation Engineers, 65th Annual Meeting; 1995; pp.214-218.
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Public opinion as to the benefits of dual left turn lanes, when compared to delays, may also need to be considered. In an article by Buckholz20, dual left turn lanes is one of the author's top 10 pet peeves:
"If one left turn lane is good, then shouldn't two left turn lanes be better? Not necessarily. Two left turn lanes require the use of protected/prohibited left turn phasing whereas a single left turn lane can be controlled by less restrictive protected/permissive phasing (or permissive phasing). Unless peak hour traffic volumes at the intersection are such that a dual left turn lane is really needed (and this is best determined through a formal intersection capacity analysis), or unless protected/prohibited phasing is needed for some other reason (such as sight restriction or a bad collision history), a single left turn lane is preferable.
If it is expected that traffic volumes will increase to the point that a dual left turn lane will be needed in the future, then room can be set aside in the median for a future second left turn lane or the second lane can be installed now but "striped out" for future use."
Not relevant to traffic signal control strategies, but perhaps significant when considering whether or not to 'squeeze' a dual left turn lane configuration into an existing urban street is lane width. In an article by Bosch21, it is reported that highway design and safety standards indicate that the normal width of a travel lane is 37m. As the width of a lane is decreased due to construction costs, topography, or other factors, the likelihood of collisions is increased dramatically. In a Kentucky study, the reported collision rate increased by 44 percent on rural two-lane highways when the lane width was 3.35m compared to 3.7m. The same study found that lane widths of 3.0m resulted in a 53.5 percent increase in the collision rate. Similar findings were reported for urban streets and freeways/expressways.
Kulash22 addressed issues concerning traditional neighbourhood development (TND). The author looks at creating a better environment for bicycles and pedestrians. Specific problems with larger arterials are:
‹ Large-radius, high-type traffic engineering features, ‹ Shallow-angle crossings at ramps and turn-lanes,
‹ Monstrous pavement expanses to be crossed, ‹ Hostility of dual left turn lanes to any type of human habitation, and ‹ General feelings, by walkers and cyclists, of being in an alien moonscape.
20 Buckholz, Jeff; "Ten Common Deficiencies of Signalized Intersections"; IMSA Journal; May/June 2002; p.28. 21 Bosch, Donald A. et al.; "10% Solution"; from http://www.criminaljustice.org/CHAMPION/ARTICLES/ 98jun06.htm; 1998. 22 Kulash, Walter; “Traditional Neighbourhood Development: Will the Traffic Work?”; Presented at the 11th Annual Pedestrian Conference, Bellevue WA, October 1990. Available: http://user.gru.net/domz/kulash.htm
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The Colorado/Wyoming Section of ITE23 determined that the largest increases in average delay for dual left turns were at locations with low opposing approach volumes, where adequate gaps were available for making permissive dual left turns. Similarly, left turn delay increases would likely be significant at most intersections during off peak conditions. This analysis indicates an overall reduction resulting from the conversion of protected-permissive dual left turns to protected-prohibited operation
The study determined that the use of protected-permissive dual left turn phasing improves intersection operational efficiency, resulting in significantly lowered delay and fuel consumption. The operational benefits associated with permissive operation of dual lefts provide a strong incentive to seek to identify locations and conditions under which this type of left turn operation can occur in reasonable safety.
2.6 SAFETY ISSUES FOR TRAFFIC CONTROL STRATEGIES AT MLTL
In a 1995 article by Shebeeb24, the results of a study that addresses the safety and efficiency of exclusive left turn lanes at signalized intersections are described. While several combinations of left turn signal phase patterns and indication sequences exist for left turn treatments and operations, there are no comprehensive guidelines to assist traffic engineers in selecting appropriate phasing type and sequence.
This study was undertaken to examine safety and efficiency of left turn movements at signalized intersections, based on left turn collision data in three consecutive years and the average left turn stopped delay per vehicle in the peak hour period. The study's purpose was to attempt to develop models that capture potential trade-offs between left turn efficiency and safety.
There are seven patterns for left turn phasing:
‹ Permissive only,
‹ Lead - protected-prohibited, ‹ Lag - prohibited-protected, ‹ Lead - protected-permissive,
‹ Lag - permissive-protected, ‹ Lead Dallas, and ‹ Lag Dallas.
23 Traffic Signal Technical Committee of the Colorado/Wyoming Section of ITE;1995. 24 Shebeeb, Ousama; "Safety and Efficiency for Exclusive Left Turn Lanes at Signalized Intersections"; ITE Journal; July 1995; p.52-59.
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Data was collected from 54 intersections in Texas and Louisiana. Intersections were videotaped and the geometric/control features of each intersection were recorded manually at each site including, number of lanes, number of opposing lanes, phase pattern, and indication sequences. Based on the data collected, the following conclusions were drawn:
‹ No significant difference was detected in efficiency or in safety between lead and lag operations for protected-prohibited phasing, protected-permissive phasing or Dallas phasing. ‹ While protected only phasing was significantly less efficient than protected- permissive, it is significantly safer.
‹ Protected-prohibited phasing was significantly less efficient than Dallas phasing; there is no significant difference in safety between the two phasing types. ‹ Statistical comparisons did not show significant differences in efficiency or in safety between protected-permissive phasing and Dallas phasing. ‹ Dallas phasing results in few collisions compared to conventional protected- permissive phasing since it was specifically designed to eliminate the yellow trap problem. ‹ Permissive phasing was more efficient than protected-permissive, but there are no significant differences in safety between the two phasing types.
‹ A definite trade-off exists between left turn collision rates and left turn stopped delays.
Driver reaction to amber and red traffic signals was documented in a study completed in Charlotte, NC25, where issues of safety investigated the distribution of left turns on amber and red from exclusive dual left turn lanes during saturated conditions (i.e. for queue lengths of five or more vehicles/lane). There were several key findings:
‹ The average number of left turns on amber and red tended to increase as average left turn green time decreased. ‹ Also, as expected, the average number of left turns on red tended to increase with the average number of left turns on amber. ‹ The distribution of left turns on amber and red by lane suggest some interesting differences in the operating characteristics of the two turn lanes:
o The average number of left turns on amber does not appear to differ substantially between the turn lanes. o On average, drivers in lane 2 (the outside lane) made fewer left turns on red than drivers in lane 1 (the inside lane), particularly when the left turn green time was relatively short.
25 Shaik (1996); pp.26-33.
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o Drivers in lane 2 of the dual left turn movement exhibited a slight tendency to make fewer left turns on red than drivers in lane 1 (this can be attributed to the Houston sites where average left turn green times were typically on the order of 10 seconds or less). o A detailed investigation of the possible sources of the seeming hesitancy of drivers in lane 2 to enter the intersection on red is beyond the scope of the study. One possible explanation, however, affecting the decision to enter (or not to enter) the intersection on red may be a function of the degree of exposure experienced by the vehicles in the two lanes. Drivers in lane 2 may simply feel “less protected” from the opposing traffic streams than their counterparts in lane 1 (speculation only).
From the Charlotte study, findings indicate that the average numbers of left turns on amber and red, for saturated cycles with relatively short green times (e.g. about 10 sec), one could expect 4 vehicles/cycle to enter the intersection from the two turn lanes combined after the end of the actual green period. Because of the exploratory nature of the analyses, caution is advised, however, in suggesting that the length of the green period affects turning on amber and red. Another possible explanation may be indicative of a capacity (delay) problem.
When pedestrian crossings are a consideration, Tian26 proposes that when the timing is based on pedestrian minimums, using a lead/lag phasing scheme for the side street can reduce the minimum cycle length constraint. This is compared to a normal dual left turn leading phase scheme.
2.7 DRIVER UNDERSTANDING OF TRAFFIC CONTROLS STRATEGIES
While not specifically addressing dual left turn lanes, a number of studies have been completed on driver understanding of signal control strategies in left turn situations. These findings have some significance to this literature review.
In 1988 a survey of licensed drivers was conducted at the Indiana State Fair27 to determine motorists' understanding of, and preference for, left turn signal alternatives, including permissive, protected-prohibited, protected-permissive signals, and leading and lagging phase sequences. Surveys were received from a diverse, but generally representative, sample of over 400 people. The following signal alternatives were included in the survey:
26 Tian, Zong Z. et al.; "Signal Timing Strategies in Dealing with Pedestrian Crossings"; Proceedings, 69th Annual Conference, Institute of Transportation Engineers; 1999. 27 Hummer, Joseph E. et al.; “Motorist Understanding of and Preferences for Left Turn Signals”; Human Factors and Safety Research Related to Highway Design and Operation; Transportation Research Record 1281; 1990; pp.136- 146.
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‹ The permissive scheme, under which vehicles may turn left when receiving a green ball signal and when sufficient gaps appear in the opposing traffic stream, which also has a green ball signal.
‹ The protected-prohibited scheme, under which vehicles may turn left only when receiving a green arrow signal that affords them the exclusive right-of-way through the intersection.
‹ The protected-permissive scheme, under which vehicles may turn left when receiving a green arrow (right of way), and may also turn left at another point in the cycle during the green ball (yielding to on-coming traffic).
Results indicated that:
‹ The protected-prohibited signal was by far the best understood, ‹ The protected-permissive signal was the least understood,
‹ The Left Turn Yield on Green (circular green) sign proved more confusing than the other protected-permissive signing alternatives tested, but there was little to distinguish the protected signal signing alternatives tested,
‹ The protected-prohibited signal was the most preferred signal because most respondents associated it with less confusion, ‹ The permissive signal was least preferred, and
‹ For a wide variety of reasons, respondents expressed a greater preference for the leading over the lagging sequence.
Bonneson28 describes a second research project that was conducted by the Nebraska Department of Roads to determine if some protected-permissive left turn signal designs cause more confusion and/or operational and safety problems for left turning drivers than others. This objective was accomplished by conducting studies of driver behaviour, driver understanding, and collision history. The research focused on a survey of driver understanding of protected-permissive designs. Findings from the studies of driver behaviour and collision history are described in the final project report (Bonneson, James A. and Patrick T. McCoy,"Evaluation of Protected/Permissive Left Turn Traffic Signal Displays", Research Report No. TRP-02-27-92, Nebraska Department of Roads, Lincoln, NE, October 1993).
The survey contained questions about six protected-permissive signal design types. An auxiliary sign was indicated in the survey for one protected-permissive design type. It was reasoned that differences in driver understanding among the seven protected-permissive designs could be attributed to a combination of both the protected-permissive signal design and the indicator presented. Therefore, to fully test the effectiveness of the seven protected-
28 Bonneson, James A. and Patrick T. McCoy; "Driver Understanding of Protected/Permitted Left Turn Signal Displays";Transportation Research Board 73rd Annual Meeting; January 9-13; paper 940505; 1994.
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permissive designs, the survey was designed to evaluate each protected-permissive design under each unique indication combination. The four different combinations considered include:
‹ Permissive only left turn indication (green ball for both the left turn and through movements), ‹ Protected/MUTCD left turn only indication (left turn green arrow and through red ball), consistent with MUTCD specifications, ‹ Overlap left turn and through indication (left turn green arrow and through green ball), and,
‹ Protected/Modified left turn-only indication. The modified indication displayed only the green arrow in the protected-permissive head (i.e. without the red ball). This form is intended to overcome driver confusion from the simultaneous display of a green arrow and red ball in the same protected-permissive head.
Results of the survey indicated that:
‹ The highest proportion of drivers correctly understands the exclusive-vertical protected-permissive design, as shown in the figure provided below, and
‹ Of the three indications considered, the least number of drivers understands the Overlap indication (by only 1/2 of all drivers).
An analysis of the effects of protected-permissive signal head location and sign use on driver understanding revealed several interesting trends:
‹ The exclusive-head location increased driver understanding about 4 or 5 percent over the shared-head location ‹ The analysis of sign use compared the exclusive cluster/vertical, as indicated on the figure below, with and without a sign. The sign considered was the "Left Turn on
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Yield Green (symbolic green ball)". This analysis indicated that designs with a sign decrease driver understanding about 6.5 percent. It was found that the sign tends to confuse more drivers during the overlap and protected phases than it helps during the permissive phase.
An examination of the differences between the MUTCD and modified form of the protected- permissive indication revealed that drivers better understood the modified form (i.e. green arrow/no red ball). The most significant difference was found for the horizontal protected- permissive designs, where 25 percent more drivers understood the modified indication. This difference is statistically significant and of sufficient magnitude to be of practical significance.
As a result of this research, it was recommended that a study of driver performance (under real-world or simulated conditions) be conducted to more precisely evaluate the level of confusion that apparently exists between it and the existing MUTCD version of the protected indication.
A study of motorist understanding of left turn signal indications and auxiliary signs was also completed in Texas, as described in a 1992 paper by Williams29. A mail survey of 6,000 drivers in Texas was conducted to assess motorists' understanding of left turn signal indication and accompanying auxiliary signs. Following are principle conclusions and recommendations were as follows:
‹ It may appear alarming that such a large fraction of drivers misunderstood some of the more commonly used left turn treatments. However, it must be kept in mind that only a single signal interval is shown in the questionnaire and that the respondent was deprived of many audio and visual clues available in the field. ‹ Sound engineering practice dictates that each signal indication should be self- sufficient; that is, it should convey a complete message by itself. This survey
29 Williams, James C. et al.; “Motorist Understanding of Left Turn Signal Indications and Auxiliary Signs”; Safety Research: Heavy Vehicles, Information Systems, and Crash Studies and Methods; Transportation Research Record 1376; 1992; pp.57-63.
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provides a good measure of this feature, and guidelines concerning the use of specific indications can be drawn from it. Ideally, motorists should understand all signal indications, under all conditions, regardless of the absence or presence of clues.
From the observations, the following recommendations were made:
‹ If red arrows are used, an educational program should accompany their use. They were not well as understood as a circular red to prohibit left turns during a particular interval, but red arrows are seldom used in Texas. One advantage of the use of red arrows is that auxiliary signs are not necessary on the left turn signal head. ‹ A green arrow should always be used for protected left turns. Even when an auxiliary sign was used with a circular green intended for left turns, the fraction of respondents answering incorrectly was higher than for equivalent cases with green arrows.
‹ A red circular and a green arrow should not be shown simultaneously on a five- section head. This indication is used to indicate a protected left while the through traffic is allowed to go. When the circular red was removed, the fraction of respondents answering incorrectly dropped. ‹ A recommendation for the auxiliary sign is more difficult to make. A primary disadvantage of any auxiliary sign is that it is difficult to read at night unless it is directly illuminated. ‹ Signs that state lefts were protected on the green arrow are superfluous because drivers appeared to have a good understanding of the meaning of the green arrow.
‹ The greatest confusion is created when a circular green is applied to left turns - does it provide for protected or permissive operation? If a sign is necessary, one that indicates that left turn traffic must yield on the circular green is preferred.
‹ "Left Turn Yield on Green" (circular green) should be used, if necessary, when permissive turning is allowed. "Left Turn on Green After Yield" is not as clear because neither circular green nor green arrow is specified.
In another study, Knodler30 describes a driver comprehension evaluation of permissive indication of protected-permissive displays completed using full-scale dynamic driving simulators at the University of Massachusetts - Amherst (UMass) and the Texas Transportation Institute (TTI). The objective of the research was to evaluate the safety and effectiveness of selected protected-permissive signal displays and phasing for protected- permissive control.
Knodler reports that, while dedicated turn lanes and protected left turn phases have improved intersection operation and safety, this has been done at the expense of intersection efficiency.
30 Knodler, Miache A. Jr., et al.; "Comparison of the Green Ball and Flashing Yellow Arrow Permitted Indications"; Institute of Transportation Engineers, 2002 Annual Conference; 4 - 7 August, 2002.
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protected-permissive signal phasing can lead to an increase in left turn capacity and reduced delay, improving operational efficiency of the intersection, but needs to be correctly presented to the driver.
While the paper does not specifically talk about dual left turns, the information provided might have some relevance to dual left turn configurations. The study suggests that, despite increase in left turn capacity achieved with protected-permissive control, problems with protected- permissive signal phasing related to the green ball permissive indication have been identified but not resolved. While opinions are mixed, it was suggested that driver interpret the green ball permissive indication as a protected indication, creating a safety problem. Research has identified at least seven unique combinations of protected-permissive signal displays and permissive indications in the United States.
The driver simulation experiment resulted in several findings:
‹ The gap sequence of the opposing traffic was selected such that drivers waiting to make a left turn would have sufficient time and space to do such; however, in the simulator, many drivers opted to wait for all of the opposing vehicles to pass before proceeding with the left turn manoeuvre even when they understood the permissive indication. As a result this response (fail-safe by traffic), which was originally considered to be an incorrect response, was considered as a correct response throughout the analysis. ‹ The percentage of correct response to the 12 protected-permissive signal displays ranged from 89 to 94 percent and there was no statistically significant difference.
‹ Within the data set there were no significant differences among the protected- permissive display components. Specifically, there was no significant difference in the percentage of correct components, nor was there a significant difference in the percentage of correct responses by permissive indication (Green Ball, Flashing Yellow Arrow, or Green Ball/Flashing Yellow Arrow), protected-permissive display arrangement (five cluster, four-section vertical, or five-section vertical), protected- permissive display location (shared or exclusive), or adjacent through indication (Green Ball or Red Ball). ‹ Overall, the percentage of correct response for drivers participating in the experiment at TTI were statistically higher than drivers at UMass; however, when the data is cross-analyzed by the 12 experimental protected-permissive signal displays and geographic location, there is no significant differences in the percent of correct responses.
A complete analysis of the permissive indications is being conducted as a component of NCHRP 3-54(2). In addition to the simulator data, this study will present a statistical analysis of incorrect responses, demographic data, and the results of a simultaneously conducted static evaluation are being conducted.
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Age can also determine the level of driver understanding in a complex driving situation. In research completed by the National Highway Traffic Safety Administration31, the project's objective was to identify and prioritize, in terms of likely consequences for safe driving performance at intersections, the age-related decrements in functional capability that can be linked through empirical or logical inference to increased crash risk. The report addresses older drivers' unsafe behaviours leading to intersection negotiation problems. Specific to left turns was a comparison of responses from drivers aged 66-68 and 77 and older that showed the older group had more difficulty following pavement markings, finding the beginning of the left turn lane, driving across intersections, and driving in the daytime.
Turning left at intersections was perceived as a complex driving task, made more difficult when channelization providing visual cues was absent, and only pavement markings designate which lane ahead is a through lane and which is a turning lane. The cognitive process of lane location detection and selection must be made upstream, at a distance where a lane change can be performed safely. Late detection by older drivers will result in lane weaving close to the intersection, a behaviour for which older drivers exhibited difficulties. Also, in the case of channelized dual left turn, maintaining lane position without conflict, is complex and uncertain for many drivers, but particularly so for senior drivers. For the oldest age group, pavement markings at intersections were the most important item, followed by the number of lanes, concrete guides, and intersection lighting. When prioritizing problems at intersections with specific driver behaviours, seventh on the list was lane keeping and avoiding sideswipe crashes when using dual left turn lanes and eighth on the list was merging with adjacent traffic in a dual left turn situation when a lane drop occurs after the turn.
The study also determined that several problems complicate safe left turns in the phase of a steady green light. These include oncoming vehicles, path search, lane keeping, and uncertainty. Multiple left turn lanes can also lead to uncertainty leading to unexpected lane changes, while lane keeping deficiencies can lead to encroachment upon neighbouring lanes.
2.8 LITERATURE REVIEW CONCLUSION
While a number agencies and associations, primarily in the United States, have undertaken a studies of traffic control for dual left turn lane situations, there appears to be no consistent application of traffic control strategies at dual left turn lanes. These studies have, however, documented a range of traffic control strategies that have been applied to dual left turn lane situations.
31 NTIS; “Intersection Negotiation Problems of Older Drivers Volume II: Background Synthesis on Age and Intersection Driving Difficulties”; Available: http://www.nhtsa.dot.gov/people/injury/olddrive/olddrivervol2.htm
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2.9 LITERATURE REVIEW BIBLIOGRAPHY
Agent, Kenneth R.; “Guidelines for the Use of Protected/Permissive Left Turn Phasing”; ITE Journal; July 1987; pp.37-42.
Asante, Seth A., Siamak A. Ardekani, and James C. Williams; “Selection Criteria for Left Turn Phasing and Indication Sequence”; Transportation Research Record 1421; Transportation Research Board; 1993.
Billingsley, Lee E. et al.; “Left Turn Phase Design in Florida”; From the Florida Section ITE; ITE Journal; September 1982; pp.28-35. Bonneson, James A. and Patrick T. McCoy; “Driver Understanding of Protected/Permitted Left Turn Signal Displays”; Prepared at Transportation Research Board 73rd Annual Meeting; Paper 940505; January 9-13, 1994. Bosch, Donald A. et al; “10% Solution”, from: http://www.criminaljustice.org/CHAMPION/ARTICLES/98jun06.htm Buckholz, Jeff; “Ten Common Deficiencies of Signalized Intersections”; IMSA Journal; May/June 2002; p.28.
Carnahan, Chris R. et al.; “Permissive Double Left Turns: Are They Safe?”; Traffic Signal Committee of the Colorado/Wyoming Section of ITE; 1995. “Guidelines for Left Turn Treatment”; Traffic Engineering Manual: Signals; Florida; Available: http://wwwII.myflorida.com/traffic Hummer, Joseph E. et al.; “Motorist Understanding of and Preferences for Left Turn Signals”; Human Factors and Safety Research Related to Highway Design and Operation; Transportation Research Record 1281; 1990; pp.136-146. NTIS; “Intersection Negotiation Problems of Older Drivers Volume II: Background Synthesis on Age and Intersection Driving Difficulties”; Available; http://www.nhtsa.dot.gov/people/injury/olddrive/olddrivervol2.htm ITE Technical Council Committees 5P-5 and 5S-1; “Capacities of Double and Triple Left Turn Lanes”; Compendium of Technical Papers; Institute of Transportation Engineers; 1995; pp.209-213. ITE Technical Council Committee 5P-5; “Technical Council Report Summary: Capacities of Multiple Left Turn Lanes”; ITE Journal; Institute of Transportation Engineers; September 1993; p.31. Knodler, Miache A. Jr., et al.; “Comparison of the Green Ball and Flashing Yellow Arrow Permitted Indications”; Institute of Transportation Engineers, 2002 Annual Conference, 4 - 7 August 2002.
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Koupai, Parvis A. and Amit M. Kothair; “Recommended Guidelines for Protected/Permissive Left Turn Phasing”; Proceedings; 69th Annual Conference; Institute of Transportation Engineers; 1999.
Kulash, Walter; “Traditional Neighbourhood Development: Will the Traffic Work?” Presented at the 11th Annual Pedestrian Conference; Bellevue WA; October 1990. Available: http://user.gru.net/domz/kulash.htm
National Cooperative Highway Research Program Report 345; “Single Point Urban Interchange Design and Operations Analysis”; Transportation Research Board; December 1991.
Shaik, Riya A. and Johnny R. Graham; “Efficiency of Dual Left Turn Lane Intersections in Charlotte: A Study Using TRAF-NETSIM”; ITE Journal, April 1996, pp.26-33. Shebeeb, Ousama; “Safety and Efficiency for Exclusive Left Turn Lanes at Signalized Intersections”; ITE Journal; July 1995; pp.52-59. Stokes, Robert W., Caroll J. Messer, and Vergil G. Stover; “Left Turns on Amber and Red from Exclusive Double Left Turn Lanes”; ITE Journal, Institute of Transportation Engineers, January 1986; pp.50-53. Tian, Zong Z. et al.; “Signal Timing Strategies in Dealing with Pedestrian Crossings”; Proceedings; 69th Annual Conference, Institute of Transportation Engineers; 1999.
“Traffic Engineering: Traffic Control Signal Design Manual”; Connecticut Department of Transportation. Available: http://www.dot.state.ct.us/bureau/eh/ehen/traffic/manual/mainindex.htm
Traffic Signal Technical Committee of the Colorado/Wyoming Section of ITE; “Permissive Double Left Turns: Are They Safe?”; Institute of Transportation Engineers, 65th Annual Meeting; 1995; pp.214-218.
Williams, James C. et al.; “Motorist Understanding of Left Turn Signal Indications and Auxilary Signs”; Safety Research: Heavy Vehicles, Information Systems, and Crash Studies and Methods; Transportation Research Record 1376; 1992; pp.57-63.
Wortman, Robert H.; “Capacity of Dual Left Turn Lanes: State of the Art”; Peter A. Mayer & Associates, prepared for Arizona Department of Transportation; Published by National Technical Information Service, U.S. Department of Commerce; Report Number FHWA- AZ87-820; October 1987.
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3.0 STATE OF THE PRACTICE
3.1 INTRODUCTION
A survey of Canadian agencies* was conducted to identify and document the traffic control strategies for dual left turn lanes, how they were developed, and how they are implemented. In particular, any warrants related to traffic control for dual left turns that have been developed by agencies were collected and summarized. The survey also included questions about any safety analysis done on dual left turn situations within their jurisdiction.
The jurisdictions that participated in the survey are included in Table 3.1.
Table 3.1: Participating Agencies
Name Title Jurisdiction
Cathy Robertson, P.Eng. Manager, Traffic Operations Town of Oakville
Chi Y. Lee, P.Eng. Traffic Engineer City of Red Deer Manager, Traffic & Transportation David McCusker, P.Eng. Halifax Regional Municipality Services Cam Nelson, P.Eng Coordinator, Traffic Safety Unit City of Calgary
Robin King, P.Eng. Transportation Engineer City of St. John's Director, Transportation and Engineering Thomas W. Mulligan, P.Eng. City of Mississauga Planning Brian Johnson, P.Eng. Traffic Operations Manager City of Lethbridge
Gord Cebryk, P.Eng. Centre Director, Traffic Engineering City of Edmonton Regional Municipality of Senior Transportation Engineering James McIlveen, R.E.T. Wood Buffalo (Fort Technologist McMurray) Dennis Mark, P.Eng. Project Engineer, Municipal Works City of Medicine Hat
Richard Nassi* City of Tucson, Arizona
*Requested to participate in the survey.
Unfortunately, several jurisdictions who had expressed an interest in participating did not return completed surveys. These jurisdictions spanned the provinces of British Columbia, Manitoba, and Québec.
3.2 SURVEY DESIGN
The consulting team developed a survey form, and had it reviewed by the PSC to confirm that the survey was designed appropriately, and that it asked the right questions. The survey was
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kept as short as possible to encourage a good response. The survey included sections to build an inventory of intersections with alternative dual left turn phasing and configuration, a section to help determine the preferred sequence for implementing additional phases for dual left turns, a section on what criteria each jurisdiction uses to evaluate signal phasing alternatives, a section to determine if each jurisdiction has a preference of signal phasing sequences and a section on whether any jurisdictions have undertaken any studies involving collisions at intersections with dual left turns.
The survey itself can be found in Appendix ‘A’ and a summary of the questions and answers of those surveys submitted to date are provided in following sections.
3.3 SURVEY RESULTS
3.3.1 Inventory of Alternative Signal Phasing Locations
Table 3.2 shows a cumulative total dual left turn type and associated phasing scheme of survey respondents.
Table 3.2: Inventory of Alternative Phasing and Left Turn Type
Slotted Left Turn Parallel Left Turn Lanes Lanes Signal Phasing Total
Type
Permissive Only 21 16 232 269
Protected- 68 26 149 243 Permissive
Protected- 47 15 27 89 Prohibited
Split Phase 89 45 4 138
Total 225 104 412 739
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3.3.2 Order of Phasing Implementation
In many jurisdictions, signal phasing at an intersection evolves over time from two-phase operations to multi-phase operations depending on traffic volumes, delay, etc. Jurisdictions were asked if they had a preferred sequence for implementing additional phases for dual left turns. The responses and comments are included in Table 3.3.
Table 3.3: Phasing Implementation Sequence Preferences
Implementation Sequence Responses Comments No preference 3 Permissive ‰ Protected-Prohibited 1 Permissive ‰ Protected-Permissive ‰ 4 Protected-Prohibited Permissive ‰ Protected-Prohibited ‰ 0 Protected-Permissive Permissive ‰ Protected-Permissive ‰ 1 Protected Prohibited ‰ Split Only Protected-Prohibited or Split Other (Please Describe) 4 Phasing Note that both Lethbridge and Tucson indicated two preferences for phasing implementation sequence.
3.3.3 Dual Left Turn Phase Decision Warrants
Jurisdictions were asked if they had warrants specifically related to the decision to move to the next sequence of phasing for dual left turns and if so, to briefly describe and attach the warrant. Comments included:
‹ N/A – as we have not changed the phasing at any of our dual left turn locations,
‹ Permissive phasing is not allowed for dual lefts (although one exception exists). The decision between split phasing and protected-prohibited phasing is based on volumes and what provides best service,
‹ Left turn volume approaching 500 vph, intersection geometrics – short storage lanes, ‹ All dual lefts done as protected only, ‹ No. The City of Edmonton has no warrants specifically for dual left turns. The same warrants as for single left turns are used to determine the phasing for dual left turns, ‹ Yes. The warrants related to the decision to move to the next sequence of phasing are the same as for single left turn and is outlined in Table 3.4, ‹ By consultant, on review of signal timing, ‹ Peak hour turns greater than 300, and
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Criteria Permissive Protected - Permissive Protected - Prohibited
1. Speed Oakville, Lethbridge 60 - 85 Calgary, Halifax, Red Deer- Read Below, Lethbridge Lethbridge 2. Number of Opposing Oakville, Lethbridge Calgary, Halifax, St. John's, Lethbridge, Red Deer - Yes if: Lanes Lethbridge - left turns cross 4 or more opposing through lanes or; - left turns cross 3 or more opposing through lanes where speed limit of opposing traffic equals or exceeds 70km/hour. 3. Collision Experience Oakville, Edmonton > 2 per year LTXP over 3 years Calgary, St. John's, Lethbridge, Red Deer - Yes - if "Left turn Lethbridge Lethbridge across path" collisions exceed 7 over a three-year period. 4. Traffic Volume Mississauga Calgary, Halifax - Opposing Volume Oakville, Lethbridge - 10% of Calgary, Halifax, St. John's, Lethbridge Medicine Hat, Lethbridge - Left Turn Volume Mississauga Edmonton Minimum 3 veh/cycle during peaks, and/or Calgary, Halifax, St. John's, Lethbridge queue of > 2 veh/sysle at start of green 5. Volume to Capacity Mississauga Calgary, Halifax Ratio (V/C) - By Movement Oakville Edmonton vehicle queues extend out of left turn lane Calgary, Halifax, St. John's - By Approach Calgary, Halifax - Overall Intersection Mississauga, Edmonton the left turn phase will not cause the degree Calgary, Halifax Medicine Hat of saturation for any through phase to exceed 0.85 6. Delay Calgary, Halifax - By Movement Oakville frequent (>50%) left turn delays of one cycle or more Calgary, Halifax, St. John's - By Approach Calgary, Halifax - Overall Intersection Edmonton the left turn phase will not increase Calgary, Halifax intersetion delay by more than 20% 7. Geometrics Oakville, Edmonton an exclusive left turn lane exists, and/or turns Calgary, Halifax, St. John's, Red Deer - Yes - if sight distance Mississauga, can be made from more than one lane is restricted, Medicine Hat 8. Other - Please Specify Edmonton fewer than 50% of left turns made on green, Calgary, Halifax and/or more than average of 2 veh/cycle on intergreen Red Deer -If left turn movement satisfies Part C: Warrant Criteria (over 30 cycles Red of the "Detailed Assessment of the Requirement for a Left-Turn Deer If left turn movement satisfies Part C: Warrant Phase" of Canadian MUTCD, plus any one of the above criteria. Criteria of the "Detailed Assessment of the Requirement This warrant is used for single and dual left turn arrangements. for a Left-Turn Phase" of Canadian MUTCD. This warrant is used for single and dual left turn lane arrangements.
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‹ Collision experience is monitored and is the reason to move from permissive- protected operation, however the offset dual left turn lanes work well and we have not had to alter the system for a number of years.
3.3.4 Criteria for Phasing Alternatives
Jurisdictions were asked to indicate all criteria used to evaluate signal phasing alternatives for dual left turn lanes. Several indicated that they used one or more criteria to evaluate alternatives. Criteria cited were: ‹ Speed, ‹ Number of Opposing Lanes,
‹ Collision Experience, ‹ Traffic Volume, ‹ Volume-To-Capacity Ratios,
‹ Delay, and/or ‹ Geometrics.
In addition, one other comment received was:
‹ There are no criteria under which we consider permissive or protected-permissive phasing. Protected-prohibited phasing is preferred over split phasing when left turning volumes are much less than through volumes.
3.3.5 Signal Phasing Sequence
Jurisdictions were asked if they had a preference of signal phasing sequence (i.e. leading phases only) for dual left turns. The responses are included in Table 3.5.
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Table 3.5: Phasing Sequence Preferences
Phasing Sequence Responses Comments Leading Left Turn Only 6 o At intersections where it would improve coordination or intersection operation, lagging left turn phasing is used.
Lagging Left Turn Only 2 o Lagging is preferred when opposing left turn movement is prohibited. Otherwise only leading is allowed.
Either Leading or Lagging 2 o Standard practice has been leading, but we are now implementing some lagging due to considerations such as coordination. o Leading left turn phases is used in a majority (roughly 85%) of situations. However, at intersections where it would improve coordination or intersection operation, lagging left turn phasing is used.
In addition one other comment received was:
‹ All signals are set up for traffic actuation. All dual lefts are split phase operation. Generally only one leg of intersection has dual lefts.
3.3.6 Collision Data
Jurisdictions were asked to provide collision studies if previously taken. There are very few jurisdictions that have done any in-depth dual left turn collision analysis. Three municipalities have performed some dual left turn collision studies. They are Red Deer, Lethbridge, and Tucson. Their comments were as follows:
‹ Signalized intersections with dual left turn lanes have been compared with signalized intersections without dual left turn lanes based on 10-year collisions statistics. Comparisons are based on the following measures: o Red Deer’s left turn collision prediction model,
o Total intersection collisions and rates, o Total intersection fatal & injury collisions and rates, o Total intersection left turn collisions and rates,
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o Total intersection left turn fatal & injury collisions and rates, o Intersection Collision Seventies type distribution, o Intersection Collision Temporal & Environnemental type distribution,
o Intersection Collision Driver Action type distribution, o Intersection Collision Crash type distribution, and o Before and after comparison for dual left turn lanes installation.
‹ At one location through the mission possible program. ‹ The Manager of the Traffic Engineering Division did a study of the dual operation for his Master’s Thesis. We found that collisions only increased slightly (approx. one left turn collision per year per approach – he did not monitor total collisions), with a massive increase in operational efficiency. The collision increase is far less than the collision increase we experienced when we install a new sign.
3.3.7 Signage for Dual Left Turns
Jurisdictions were asked regarding signage for dual left turns. The responses included:
‹ OTM Book #5 Pg.81,
‹ Typical TAC-standard side-mounted multiple lane designation signs are used. RB- 46L or RB-47L depending on the lane configuration, ‹ We use only TAC RB-46L and RB-47L,
‹ Regulation – HTA Standard OTM Book 12 – “Left turn signal signs”, ‹ In most cases, we use a single sign indicating dual turns by the display of two turn arrows on the sign,
‹ TAC-standard signage is used in the City of Edmonton. The signs used are RB-46L and RB-47L (600mmx600mm size), ‹ The City uses TAC standard signage. If two RB-41L signs can be placed overhead, this is the preferred method. If not, a maximum of 3 RB-46L signs can be installed. One sign is installed on the opposite side of the intersection on an opposing median and the other two signs are installed on the median prior to the intersection at 5 and 25 metres from the nose of the median. If the bay length is less than 50 metres, a sign is not installed at the 25-metre distance, ‹ Use RB-46L on protected permissive dual left turns in advance at the turn and overhead on the signal arm. ‹ TAC standard overhead is preferred but side mounted is used to reinforce. We use the RB (L) 46, 47,
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‹ Try to follow TAC – MUTCD. We use RB-46 combo of RB-44 with RB-41 over lanes, combo of RB-41 and RB-42 over lanes, and ‹ In the United States we use the MUTCD standard dual arrows showing that a “U” turn is also OK. The same is done in New York, Denver, and Texas.
3.3.8 Signal Heads and Display Configuration for Dual Left Turns
Jurisdictions were also asked for the number of signal heads and what display configuration they used for the typical dual left turn situation. Following are their responses:
‹ Two displays for every movement. Typically an auxiliary head is used for dual left operation unless it is a split phase configuration.
‹ For dual left turns at “quad” intersections with split phasing, two signal heads are used, one or both with flashing left turn arrows, depending on weather or not there is a shared through-left lane. At “quad” intersections where the dual left turn movement is protected-prohibited, a single signal head (with LED lamps and a backboard) is placed in the median – this signal head also has a sign directly below it that identifies it as a “Left Turn Signal”. Where dual left turns occurs at “T” intersections, two signal heads are used. At some locations both signals have steady green ball indicators while at others both signals have flashing green arrows instead of steady green balls.
‹ Split phasing – generally three 5-section heads: R / A / G / A< / G<. ‹ Protected-prohibited only phasing – two 3-section left heads: R / A< / G< and two 3- section thru heads: R / A / G.
‹ Three section 300 mm sections. ‹ Typically, one head with Red-Red-Amber-Green Arrow. ‹ For an advanced protected-permissive dual left turn a single vertical fixture with 5 heads (R, A, G, solid amber arrow, flashing green arrow is used. For fully protected dual left turns, a single vertical fixture with 4 heads (R, R, solid amber arrow, flashing green arrow) is used. Delayed permissive-protected dual left turns are controlled by a single horizontal fixture with 4 section heads (R, A, flashing green arrow, G). The City of Edmonton uses 200 mm fixtures, and 300 mm fixtures for speeds above 60km/h.
‹ Typically, 1 median signal, one overhead signal and one far-right secondary signal are installed. Only the median signal displays the left turn arrow. Where no median exists, the left turn signal is mounted overhead, centered as near as possible in front of the left turn lane for which it is intended. Protected-prohibited phasing display is Red Ball - Red Ball - Amber Ball - Green arrow. ‹ A minimum of two five-section signal heads R-Y-G-YA-GA.
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‹ One signal head with amber arrow display for each turn lane vertical mounting, ‹ Usually one per lane, and ‹ Primary R/A/GA flash, Auxiliary R/A/GA/G flash/no flash, Auxiliary R/A/GA flash.
3.3.9 Other Criteria for Signal Phasing for Dual Left Turns
Jurisdictions were asked if any other criteria should be considered in developing appropriate signal phasing criteria. The comments received were:
‹ A standard, if not already implemented, regarding the installation of “Shadow” Lane for the opposing left turn lane, which may not be dual, should be developed, ‹ Consideration should be given to sight line limitations imposed by a dual left turn in the opposing direction, and ‹ We have found that by offsetting the dual lefts by approximately 1.2m to 3.0m and providing the same sight distance for the left turning driver in the second lane as they would have with a single left turn lane, the dual operation, permissive-protected, works very well.
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4.0 COLLISION ANALYSIS
4.1 INTERSECTION LOCATIONS
In general, it can be said that most of the research and most jurisdictions agree that protected- permissive phasing is a more efficient strategy, but protected-prohibited phasing is safer. There does not appear to be very much empirical evidence to definitely support either side of the argument that one approach is better than another. In an attempt to identify a preferred strategy, Earth Tech gathered data for multiple intersections with dual turn lanes in the cities of Calgary and Edmonton in the province of Alberta. Information collected from Edmonton focused on their preferred sequence of protected-permissive dual left turns as compared with the City of Calgary’s protected-prohibited dual left preference. Calgarian and Edmontonian driving behaviours and characteristics are similar. Climate, which significantly impacts winter driving conditions, is generally alike in the two cities. Data for the following City of Calgary intersections were collected:
‹ 14 Street and Anderson Road SW, ‹ Glenmore Trail and Barlow Trail SE,
‹ Crowchild Trail and Nose Hill Drive NW, ‹ Shaganappi Trail and Northland Drive NW, ‹ Barlow Trail and 32 Avenue NE,
‹ 36 Street and Memorial Drive SE, ‹ 17 Avenue and Sarcee Trail SW, and ‹ Barlow Trail and McKnight Boulevard NE.
Along with the following intersections in the City of Edmonton:
‹ 23 Avenue and Calgary Trail, ‹ Yellowhead Trail and 127 Street,
‹ 118 Avenue and 97 Street, ‹ 137 Avenue and 127 Street, ‹ 137 Avenue and 97 Street,
‹ 87 Avenue and 178 Street, ‹ Agryll Road and 75 Street, ‹ Kingsway Avenue and 109 Street, and
‹ University Avenue and 114 Street.
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4.2 METHODOLOGY
Collision, volume, lane configuration, and phasing data were collected for each of the intersections mentioned in the previous section. The signal phasing and volume for the afternoon peak period, as well as intersection geometry data were used to analyze the capacity of the intersections and dual left turn movements. Collision statistics consisted of two segments: the intersection as a whole, and for individual dual left turns. Each segment is further divided into four collision categories:
• Left turn across path, • Failure to observe traffic signal, • Following too closely (rear end), and • Other causes.
Where information was available, collision data was further broken down by collision direction, day, time, and season. The project team used the collected collision data to calculate a Hazard Index for each intersection and individual dual left turn.
4.2.1 Collision Hazard Index
In order to accurately compare the collision data at each of the intersections, the collision frequency must be related to the degree of exposure that exists at the intersection. The traffic volume that traverses the intersection represents the degree of exposure. Typically, this relationship is termed “collisions per million vehicle approaches per year”. This relationship can be simplified to a term developed by H. Allen Swanson, P. Eng., MCIP called a “Hazard Index” (HI). When used for an intersection as a whole this index has the following form:
Annual Collision Frequency × 10,000 HI = Daily Intersection Approach Volume
The difference between the two indices is a factor of 3.65. That is, to calculate the Hazard Index from a collision rate based on million-vehicle entries/year, multiply the latter rate value by 3.65.
A Hazard Index was calculated for each intersection and each individual left turn movement. When the Hazard Index is used to define an individual dual left turn movement it has the following form:
Annual Collision Frequency × 10,000 HI = LT Daily Conflicting Volume
The daily conflicting volume is the sum of the daily dual left turn volume and the daily opposing through volume. Note that daily volumes were calculated by multiplying the afternoon pear hour volumes by a factor of 12.
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4.2.2 Capacity Analysis
Capacity analysis for each intersection was completed using Trafficware’s Synchro 5 analysis software. Synchro 5 predominantly uses methodology outlined in the Highway Capacity Manual (HCM) – 2000 Edition for signalized intersections, as described below.
The Level of Service (LOS) grading scale for intersection analysis is based on average control delay per vehicle. LOS ranges from ‘A’ to ‘F’, where LOS ‘A’ reflects ideal free flow conditions with little or no delay, and LOS ‘F’ indicates general failure of the movement. Table 4.1 shows LOS criteria for signalized intersections. Control delay per vehicle is used for cost-benefit analysis later in this report.
Table 4.1: LOS Criteria for Signalized Intersections
Level of Service Control Delay per Vehicle Comment (LOS) (seconds/vehicle) A 10.0 and less Very Good Operation B 10.1 to 20.0 Good Operation C 20.1 to 35.0 Acceptable Operation D 35.1 to 55.0 Some Congestion E 55.1 to 80.0 Significant Congestion F Greater than 80.0 Unacceptable Operation
Synchro 5 calculates another measure of effectiveness of an at-grade intersection movement, the volume to capacity (v/c) ratio. The v/c ratio is an indication of the relative utilization of available capacity for a movement. Theoretically, the v/c ratio has a maximum of 1.00; in Calgary, 0.90 is the accepted general maximum used as a basis for intersection design, in Edmonton 1.00 is accepted for inner city and 0.90 is the maximum excepted v/c for suburban areas.
The maximum volume to capacity ratio for each intersection was noted along with the volume to capacity ratio for each dual left turn movement.
4.3 CAPACITY AND COLLISION ANALYSIS RESULTS
Tables 4.2 and 4.3 respectively summarize the collected data and analysis results for each of the Calgary and Edmonton intersections analyzed. Complete data sheets, including all of the collected data and analysis results for Calgary and Edmonton intersections can be found in Appendix ‘B’ and Appendix ‘C’, respectively.
4.4 DISCUSSION OF RESULTS
Figures 4.1 and 4.2 show the dual left turn Hazard Index versus the dual left turn control delay and the intersection delay respectively.
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Figure 4.1: Dual Left Turn Hazard Index and Control Delay
12
x 10 e d n I
d
r 8 a z a
H Linear (Prot + Perm)
n 6 r Linear (Protected) u T
t f
e 4 L
l a u
D 2
0 0.0 100.0 200.0 300.0 400.0 Dual Left Turn Control Delay (s/veh)
Figure 4.2: Dual Left Turn Hazard Index and Intersection Delay
12 x
e 10 d n I
d r 8 a z a
H Linear (Prot + Perm)
n 6 r Linear (Protected) u T
t f 4 e L
l a
u 2 D
0 0 20 40 60 80 100 120 Intersection Delay (s/veh)
It can be seen from Figures 4.1 and 4.2 that although the protected-permissive dual left turn phases generally have lower delay for both the dual left turns and the overall intersection, they have significantly higher dual left turn hazard indices. There are, however, protected- permissive intersections that have relatively low Hazard Indices (HI < 3); indicated with the light green coloured circle. All of the protected-prohibited dual left turns analyzed have Hazard Indices lower than 3.0, however these intersections also have higher delay than those that use protected-permissive phasing.
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Intersection Max Daily Annual Dual Left Daily Dual Left Daily Conflicting Dual Left Intersection Hazard V/C Volume Accidents Direction Turn Volume Through Volume Hazard Index Index Ratio SB 5,580 5,292 0.000 14 Street & Anderson Road SW 63,696 29 4.605 1.75 EB 4,848 16,812 1.235 NB 2,352 6,516 0.000 EB 3,012 5,064 1.177 Glenmore Trail & Barlow Trail SE 40,824 27 6.695 1.28 SB 984 3,084 1.128 WB 948 7,548 0.387 SB 4,824 9,564 0.000 Crowchild Trail & Nose Hill Drive NW 62,760 35 5.524 1.29 EB 5,100 9,312 1.433 WB 5,268 504 2.310 NB 4,692 6,240 0.382 Shaganappi Trail & Northland Drive NW 55,872 33 5.966 N/A SB 3,048 14,028 3.354 NB 2,184 8,400 1.044 Barlow Trail & 32 Avenue NE 68,208 51 7.428 1.19 SB 2,160 13,800 2.834 NB 3,072 7,716 0.308 EB 5,700 12,756 1.353 36 Street & Memorial Drive SE 71,628 53 7.353 2.53 SB 4,440 6,372 1.545 WB 4,092 15,162 1.084 EB 2,076 10,476 0.539 17 Avenue & Sarcee Trail SW 57,708 53 9.126 2.33 WB 3,036 3,144 0.801 NB 7,212 4,308 0.000 EB 3,024 10,896 0.747 Barlow Trail & McKnight Blvd NE 77,772 51 6.515 1.78 SB 2,988 8,796 0.000 WB 3,096 19,224 0.709 Table 4.3: Summary of Edmonton Intersection Analysis Results
Intersection Max Daily Annual Dual Left Daily Dual Left Daily Conflicting Dual Left Intersection Hazard V/C Volume Accidents Direction Turn Volume Through Volume Hazard Index Index Ratio NB 4,462 21,276 0.399 EB 2,748 9,204 2.076 23 Avenue & Calgary Trail* 89,160 66 7.380 1.04 SB 4,212 20,868 0.699 WB 3,276 7,320 5.857 Yellowhead Trail & 127 Street 101,580 51 5.021 1.26 EB 9,144 29,208 0.450 118 Avenue & 97 Street 60,828 30 4.899 1.03 EB 7,944 4,464 9.359 EB 7,944 8,568 2.099 137 Avenue & 127 Street 67,620 29 4.289 0.99 WB 2,208 14,940 1.817 NB 3,612 9,240 7.650 137 Avenue & 97 Street 75,960 65 8.531 1.04 EB 4,284 8,076 2.068 WB 3,240 11,268 4.369 87 Avenue & 178 Street 52,044 32 6.187 0.93 WB 3,288 3,264 5.297 EB 6,948 5,988 2.028 Agryll Road & 75 Street 67,920 40 5.919 0.92 WB 4,608 11,172 2.938 Kingsway Aveune & 109 Street 52,584 18 3.461 1.16 NB 8,592 9,432 2.967 University Avenue & 114 Street 58,764 36 6.126 2.19 NB 10,200 12,528 11.228
* At the intersection of Calgary Trail and 23 Avenue the NB and SB dual left turns use protected-prohibited phasing. 4.0 Collision Analysis
Further investigation of the protected-permissive intersections with hazard indices below 3.0 lead to a list of criteria for the implementation of protective-permissive dual left turn phases. From the data collected on Calgary and Edmonton intersections, there appears to be trends indicating when protected-permissive phasing may decrease delay without seriously increasing the number of collisions. In order to be considered for protected-permissive dual left turn phasing, an intersection should have the following characteristics:
• Slotted left turn bays to allow for maximum visibility,
• Less than three opposing through lanes,
• Low truck volumes, and
• Opposing through volumes that provide sufficient gaps in traffic for the completion of left turns.
Trends from the analyzed data also suggest when intersections should not be considered for protected-permissive dual left turn phases. Implementation of protected-permissive phasing should not occur if intersections have the following characteristics:
• Non-slotted left turn bays, unless a sufficient clearance is provided creating a pseudo- slotted turn bay (e.g. Tucson, AZ design shown in Figures 4.3 and 4.4),
• Shared left turn and through lanes,
• High opposing through volumes,
• High truck volumes, and
• Three or more opposing through lanes.
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Figure 4.3: Tucson, AZ Pseudo-Slotted Dual Left Turn Bay (Permissive Portion of Phase)
Figure 4.4: Tucson, AZ Pseudo-Slotted Dual Left Turn Bay (Protected Portion of Phase)
These recommendations are based on a relatively small sample size of intersections in Calgary and Edmonton; therefore, it is recommended that further studies are completed to test the general application of these criteria.
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5.0 COST-BENEFIT ANALYSIS
5.1 SCOPE OF ANALYSIS
The following sections document a cost-benefit analysis tool developed by Earth Tech to examine efficiency (minimizing delay) versus safety (reducing collisions) for the basic traffic control strategies (protected-prohibited versus protected-permissive). This cost-benefit analysis tool can be applied to intersections meeting the criteria discussed in Section 4.5 to assist in determining an appropriate phasing strategy.
5.2 QUANTIFICATION OF DELAY
The benefit of choosing protected-permissive dual left turn phasing over protected-prohibited is that all intersection users, not just left turners, incur less delay. The exact value of the delay savings is dependent on the number of dual left turn phases and the peak hour traffic volumes. Afternoon peak hour delay savings per vehicle can be found by comparing the delay for protected-prohibited dual left turn phases with that of the protected-permissive phase using Synchro analysis software. This afternoon peak hour delay saving is then transformed to total savings per year, first by multiplying the savings per vehicle by the total afternoon peak hour intersection approach volume, then transforming it into total intersection daily savings using Table 5.1.
Table 5.1: Afternoon Peak Hour to Daily Delay Savings for the Total Intersection
Hour Portion of Delay Savings AM 1 0.6y AM 2 0.6y Noon 1 0.5y Noon 2 0.5y PM 1 1y PM 2 1y Other 18 0.1y Total Intersection Daily Delay 6y Note: y = Total Intersection Afternoon Peak Hour Delay Savings
Next, the daily savings is converted to yearly values, assuming 320 days per year. This number is less than 365 days to account for the fact that weekend days and statutory holidays will not experience the same delay savings as weekdays.
Once the delay savings have been calculated, an hourly rate for time is applied to the savings to calculate the total benefit of implementing protected-permissive over protected-prohibited dual left turn phasing. This process can also be followed to calculate the cost of the delay
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imposed by using a protected-prohibited dual left turn strategy over protected-permissive. Fuel cost savings can be used in place of, or in conjunction with, hourly time savings and can be calculated in a similar manner to hourly time savings. Synchro 5 calculates the number of litres of fuel used in an hour at an intersection. This can be used to determine the litres of fuel that will be saved in the afternoon peak hour by the dual left phase change from protected- prohibited to protected-permissive. This savings can be converted to a daily value using the values shown in Table 5.1 and to a yearly value by multiplying by 320 days. Once the fuel savings in litres is known, it can be multiplied by the cost of one litre of fuel to get the cost savings.
5.3 QUANTIFICATION OF COLLISIONS
The cost associated with choosing protected-permissive dual left turn phasing over protected- prohibited is an increase in the number of ‘left turn across path’ collisions that occur at the intersection. With this increase however, is a decrease in ‘failure to observe traffic signal’ and ‘rear end’ collisions. In order to determine the amount increased or decreased for each collision type, an average Hazard Index was calculated for both the protected-permissive and protected-prohibited dual left turn phases. The ratio of the Hazard Indices for protected- permissive to protected-prohibited for each collision type was found. An example of this calculation follows:
Average HIProtected-Permissive = 12.50
Average HIProtected-Prohibited = 2.91
HI 12.50 HI _ Ratio = Pr otected −Permissive = = 4.298 HI Pr otected −Pr ohibited 2.91
This ratio shows that the likelihood is 4.298 times greater to be involved in a ‘left turn across path’ incident with protected-permissive phasing over that with protected-prohibited phasing. The data used to find these average Hazard Indices and corresponding HI Ratios for each collision type are found in Appendix ‘D’.
This leads to the following formula:
Cost = 4.298*(Cost of Left Turn Across Path collisions)*(Collisions/3 Years/3) 1.624*(Cost of Failure to Observe Signal collisions)*(Collisions/3 Years/3) 1.756*(Cost of Rear End collisions)*(Collisions/3 Years/3) + 4.298*(Cost of Fatal collisions)*(Collisions/3 Years/3)*(1/20)
Some left turn across path collisions ‘created’ by the change in phase will involve serious injuries or fatalities. To account for this, a percentage of the collisions should be multiplied by the cost of a fatal collision. This cost will account for the increase in both fatal and severe injury collisions and is represented by the last term in the equation.
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It is further assumed that in locations where protected-prohibited phasing is status quo, and no collisions were experienced over a three year period, a change in phasing to protected- permissive will automatically induce one collision per year (which is then multiplied by the HI Ratio of 4.298).
5.4 EXAMPLES
This section presents two sample applications of the cost-benefit analysis tool using analyzed intersections in Calgary and Edmonton. To complete the sample calculations of the cost- benefit analysis, the following assumptions were made:
• Fuel cost = $0.85/litre, • For every second time saved in the afternoon peak hour by allowing protected- permissive dual left turns over protected-prohibited, 4.5 litres of fuel are saved32, • Hourly cost of time = $12.00, • Cost of left turn across path collisions = $15,000, • Cost of failure to observe signal collisions = $6,000, • Cost of rear end collisions = $4,000, • Approximately 1 in 20 collisions caused will be fatal, and • Cost of a fatal collision = $1,400,000.
All of the above values are estimates only; it is therefore recommended that further research be completed to determine the most appropriate value local to the jurisdiction.
Jurisdictions planning on using this tool should calibrate the costs of collisions, time, and fuel to reflect local conditions.
Worksheets were compiled in Microsoft Excel to calculate a cost-benefit ratio for switching from protected-prohibited to protected-permissive and vice versa. Figures 5.1 and 5.2 show these worksheets for the intersections of 14 Street SW/Anderson Road (Calgary) and 137 Avenue/127 Street (Edmonton).
The input required for these worksheets is the intersection delay for each configuration (i.e. the protected-prohibited dual left turns and protected-permissive dual left turns), the number of dual left turn phases changed, and the total number of each collision type for changed phase over three years. Delay values can be calculated using Synchro software.
Once the required data input is implemented, a recommendation is produced based on the calculated benefit-to-cost ratio. It is suggested that no changes be implemented for a ratio lower than 1.00.
32 Calculated based on assumed parameters using Synchro. Actual fuel savings may be plus or minus 4.5 litres.
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COST BENEFIT ANALYSIS WORKSHEET Protected-Prohibited to Protected-Permissive
INTERSECTION: ANDERSON ROAD SW & 14 STREET SW
CAPACITY ANALYSIS (Completed using Trafficware's Synchro 5 software)
Current Configuration (Protected-Prohibited) Intersection Delay Intersection LOS 106.8 F Left Turn Analysis EBL WBL NBL SBL (DUAL) (DUAL) V/C Ratio 1.75 0.09 0.56 1.32 Delay 267.7 64.0 46.0 177.3 LOS F E D F
Changed Configuration (Protected-Permissive) Intersection Delay Intersection LOS 92.3 F Left Turn Analysis EBL WBL NBL SBL (DUAL) (DUAL) V/C Ratio 1.31 0.12 0.59 1.24 Delay 159.3 70.8 50.6 154.3 LOS F E D F *EBL Changed
BENEFIT ANALYSIS
PM Peak Delay Savings = 14.5 seconds/vehicle Daily Delay Savings = 87 seconds Yearly Delay Savings = 27840 seconds Fuel Savings = 4.5 L/second delay savings Fuel Price = $0.85 per litre Total Fuel Savings = $106,488 per year
PM Peak Intersection Volume = 5308 PM Peak Delay Savings = 14.5 seconds/vehicle Yearly Delay Savings = 41048.533 hours Hourly Time Rate = $12.00 Total Time Savings = $492,582 per year
COST ANALYSIS
DUAL LEFT TURN COLLISION DATA FOR CHANGED PHASES OVER THREE YEARS Number of left turn across path collisions = 0 Number of rear end collisions = 0 Number of rear end collisions = 2
Number of Dual Left Phases Changed = 1 Cost of left turn across path accidents = $15,000 per accident Cost of failure to observe signal accidents = $6,000 per accident Cost of rear end accidents = $4,000 per accident Cost of a fatal accident = $1,400,000 per accident Total Accident Cost = $360,647 per year
TOTAL BENEFIT = $599,070 TOTAL COST = $360,647 BENEFIT TO COST RATIO = 1.66
RESULT Implement Protective-Permissive Phasing Figure 5.2: Protected-Permissive to Protected-Prohibited Analysis Example
COST BENEFIT ANALYSIS WORKSHEET Protected-Permissive to Protected-Prohibited
INTERSECTION: 137 AVENUE AND 127 STREET
CAPACITY ANALYSIS (Completed using Trafficware's Synchro 5 software)
Current Configuration (Protected-Permissive) Intersection Delay Intersection LOS 37.6 D Left Turn Analysis EBL WBL NBL SBL (DUAL) (DUAL) (DUAL) (DUAL) V/C Ratio 0.99 0.55 0.68 0.83 Delay 48.3 18.5 22.9 44.1 LOS D B C D
Changed Configuration (Protected-Prohibited) Intersection Delay Intersection LOS 47.5 D Left Turn Analysis EBL WBL NBL SBL (DUAL) (DUAL) (DUAL) (DUAL) V/C Ratio 1.02 0.79 0.75 0.60 Delay 82.3 68.0 31.0 62.4 LOS F E E E
COST ANALYSIS
PM Peak Delay Costs = 9.9 seconds/vehicle Daily Delay Costs = 59.4 seconds Yearly Delay Costs = 19008 seconds Fuel Cost = 4.5 L/second delay costs Fuel Price = $0.85 per litre Total Fuel Costs = $72,706 per year
PM Peak Intersection Volume = 5635 PM Peak Delay Costs = 9.9 seconds/vehicle Yearly Delay Costs = 29752.8 hours Hourly Time Rate = $12.00 Total Time Cost Savings = $357,034 per year
BENEFIT ANALYSIS
DUAL LEFT TURN COLLISION DATA FOR CHANGED PHASES OVER THREE YEARS Number of left turn across path collisions = 19 Number of rear end collisions = 0 Number of rear end collisions = 1
Number of Dual Left Phases Changed = 2 Cost of left turn across path collisions = $15,000 per accident Cost of failure to observe signal collisions = $6,000 per accident Cost of rear end collisions = $4,000 per accident Cost of a fatal collisions = $1,400,000 per accident Total Accident Savings = $2,311,415 per year
TOTAL BENEFIT $2,311,415 TOTAL COST $429,739 BENEFIT TO COST RATIO = 5.38
RESULT Implement Protective-Prohited Phasing 5.0 Cost-Benefit Analysis
5.5 APPLICATION OF THE COST-BENEFIT TOOL
With further research into the values entered into the cost-benefit analysis, it could be a useful tool for jurisdictions considering the different types dual left turn phasing. The cost-benefit analysis, combined with Synchro traffic analysis can be used to help jurisdictions decide whether to implement protected-prohibited or protected-permissive dual left turn phasing. Also, if problems have been identified with one type of dual left turn phasing, the tool can be used to determine the benefits and costs of switching to the alternative phasing type. The cost -benefit analysis only compares protected-prohibited and protected-permissive dual left turn phasing. It should not be used to determine whether or not a dual left turn lane should be implemented in place of a single left turn lane. Jurisdictions planning on using this cost- benefit tool should use local conditions for calibration of the model.
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6.0 CONCLUSIONS
In general, it can be said that most of the research and most jurisdictions agree that protected- permissive phasing is a more efficient strategy, but protected-prohibited phasing is safer. Results of the collision analysis validate this assumption, but also show that there are exceptions. Protected-permissive dual left turn phasing can be almost as safe as protected- prohibited dual left turn phasing if it is implemented under the right conditions. Intersections with slotted dual left turn bays, less than three opposing through lanes, opposing through volumes that provide sufficient gaps for completion of left turn movements, and low truck volumes may be good candidates for protected-permissive dual left turn phasing. Research and analysis conducted as a part of this report concludes that permissive phasing with shared lane approaches (one exclusive left turn land and a shared left/through lane) create a significantly higher collision probability; shared lane approaches with opposing traffic should only use split phasing.
The results of the collision analysis presented are based on a relatively small sample size from intersections in the two largest cities in Alberta. It is recommended that further research be completed using data from other jurisdictions in other provinces and states to verify the findings presented in this report.
The cost-benefit tool developed by Earth Tech can be a useful tool for comparing protected- prohibited and protected-permissive dual left turn phasing. The benefit of protected- permissive phasing is efficiency (reduced delay) but the cost is an increase in collisions. Using locally estimated values for the cost of time, fuel, and different collision types, a dollar value for both costs and benefits can be calculated. A cost-benefit worksheet has been developed for use in this research but the values used for cost of time, fuel, and collisions are only estimates and require further research and values relative to location of analysis. It is further suggested that additional field research be conducted (before and after studies) to determine the difference in actual collision experienced with a change in left turn phasing strategy. It is further suggested that jurisdictions complete before-after studies and additional field research to refine the use of the cost-benefit tool as well as identify the actual benefit- cost ratio achieved in changing phase schemes.
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Appendix A
Dual Left Turn Survey Form
C-TEP SIGNAL CONTROL STRATEGIES FOR DUAL LEFT TURN LANES
1. Introduction On behalf of the Centre for Transportation Engineering & Planning (C-TEP), Earth Tech is currently studying signal control strategies for dual left turn lanes. The main objective of this study is to recommend, if possible, a strategy balancing the potentially conflicting desires of minimizing traffic delays and providing safe traffic operations.
As a stepping-stone to reach our objective, we are requesting input from numerous Canadian jurisdictions by way of this short survey. Through this survey, we hope to document the range of signal control strategies for dual left turn lanes currently used across Canada and how these strategies were developed and implemented. Please note that these questions pertain to dual left turn situations only.
Please take time to fill out this survey and return it to Peter Truch by Friday March 07, 2003. Email: [email protected] Fax: (403) 254-3333
2. Inventory of Alternative Signal Phasing Locations Please indicate on the following table the number of intersections in your jurisdiction that have the three types of signal phasing alternatives for dual left turns.
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Table 2.1: Inventory of Alternative Signal Phasing Locations
Parallel Left Turn Lanes Slotted Left Turn Lanes
Signal Phasing Total
Type Oakville 0 0 0 0 St. John’s 0 0 0 0 Halifax 1 0 0 0 Mississauga 0 0 0 0 Calgary 3 - 0 3 Permissive Only Edmonton 15 14 2 31 Red Deer 0 2 0 2 Wood Buffalo - - - - Lethbridge 1 - - 1 Medicine Hat - - - - Tucson 1 - 230 231 Oakville 2 0 0 2 St. John’s 0 0 0 0 Halifax 0 0 0 0 Mississauga 0 1 0 1 Calgary 0 - 0 0 Protected- Edmonton 36 22 15 73 Permissive Red Deer 0 2 0 2 Wood Buffalo 2 0 1 3 Lethbridge 2 1 - 3 Medicine Hat - - - - Tucson 30 - 132 162 Oakville 2 0 0 2 St. John’s 6 1 0 7 Halifax 7 0 0 7 Mississauga 0 12 0 12 Calgary 20 - 18 38 Protected- Edmonton 3 1 2 6 Prohibited Red Deer 2 0 5 7 Wood Buffalo - - - - Lethbridge 2 1 - 3 Medicine Hat 1 - - 1 Tucson 2 - 1 3
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Oakville 1 1 0 2 St. John’s 0 2 0 2 Halifax 2 5 0 7 Mississauga 0 1 0 1 Calgary 59 - 0 59 Split Phase Edmonton 24 30 1 55 Red Deer 0 0 2 2 Wood Buffalo - - - - Lethbridge 2 1 - 3 Medicine Hat - 5 - 5 Tucson 1 - 1 2 Oakville 5 1 0 6 St. John’s 6 3 0 9 Halifax 10 5 0 15 Mississauga 0 14 0 14 Calgary 82 - 18 100 Total Edmonton 78 67 20 165 Red Deer 2 4 7 13 Wood Buffalo 2 0 1 3 Lethbridge 6 3 1 10 Medicine Hat 1 5 - 6 Tucson 34 - 364 398
Please provide a list of up to four locations in your jurisdiction for each of the phasing and geometric conditions indicated by the gray boxes in the table above. It would be preferable if the locations represent a cross-section of central city and suburban locations.
Parallel Left Turn Lanes Slotted Left Turn Lanes
Signal Phasing Type
______Permissive ______Only ______
Protected- Permissive ______
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______
______Protected- ______Prohibited ______
______
Split Phase ______
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3. Order of Phasing Implementation
In many jurisdictions, signal phasing at an intersection evolves over time from two-phase operations to multi-phase operations depending on traffic volumes, delay, etc. Does your jurisdiction have a preferred sequence for implementing additional phases for dual left turns? Please circle your response. a) No preference b) Permissive ‰ Protected-Prohibited c) Permissive ‰ Protected-Permissive ‰ Protected-Prohibited d) Permissive ‰ Protected-Prohibited ‰ Protected-Permissive e) Permissive ‰ Protected-Permissive ‰ Protected Prohibited ‰ Split f) Other (Please Describe)
Oakville A) St. John’s F) For dual left turns, we use only protected-prohibited or split phasing. To date,we have not changed the phasing at any particular dual left turn location Halifax A) Mississauga B) Calgary F) All dual lefts done as protected only Edmonton C) Red Deer C) Wood Buffalo A) Lethbridge C) or F) Medicine Hat F) We implement split phase right away Tucson C) or E)
Are there warrants specifically related to the decision to move to the next sequence of phasing for dual left turns? If so, please briefly describe and attach the warrant. Oakville No comment St. John’s N/A – as we have not changed the phasing at any of our dual left turn location Halifax Permissive phasing is not allowed for dual lefts (although one exception exists). The decision between split phasing and protected-only phasing is based on volumes and what provides best service. Mississauga Left turn volume approaching 500 vph Intersection geometrics – short storage lanes Calgary All dual lefts done as protected only Edmonton No. The City of Edm has no warrants specifically for dual left turns. The same warrants as for single left turns are used to determine the phasing for dual left turns. Red Deer Yes. The warrants related to the decision to move to the next sequence of phasing is the same as for single left turn and is outlined in Table 4.1. Wood Buffalo By consultant, on review of signal timing Lethbridge Peak hour turns greater than 300 Medicine Hat No comment
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Tucson Accident experience is monitored and the reason to move from the permitted- protected operation, however they off-set dual left turn lanes work well and we have not had to alter the system for a number of years. The dual operation has been in operation for over 30 years now
4. Criteria for Phasing Alternatives
Please indicate on Table 4.1 all criteria your jurisdiction uses to evaluate signal phasing alternatives for dual left turn lanes. Please mark all appropriate responses with a checkmark and, when appropriate, the exact value or range used.
Halifax I haven’t filled this out since there is no criteria under which we consider permissive or protected-permissive phasing. Protected-only phasing is preferred over split phasing when left turning volumes are much less than through volumes.
5. Signal Phasing Sequence
Does your jurisdiction have a preference of signal phasing sequence (i.e. leading phases only) for dual left turns? If so, please indicate what the preference is.
Oakville Leading phases only St. John’s Leading only Halifax Lagging is preferred when opposing left turn movement is prohibited. Otherwise only leading is allowed. Mississauga Leading only Calgary No preference. Standard practice has been leading, but we are now implementing some lagging due to considerations such as coordination. Edmonton The City of Edmonton uses leading left turn phases in a majority (roughly 85%) of situations. However, at intersections where it would improve coordination or intersection operation, lagging left turn phasing is used. Red Deer Leading left turn phases are preferred Wood Buffalo Leading phases only Lethbridge Most common driver understanding/expectation is leading left turns Medicine Hat All signals in Medicine Hat are set up for traffic actuation. All dual lefts are split phase operations. Generally only one leg of intersection has dual lefts. Tucson We prefer the use of lagging operations however we use the leading lefts as intersection conditions dictate.
6. Other
Has your jurisdiction undertaken any studies involving collisions at intersections with dual left turns. If so, would we be able to have access to the studies in the near future?
Oakville No Response
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St. John’s NO. When the information is available, accident data is considered in the decision to install dual left turns, but no official study has been undertaken at either proposed or existing dual left turn locations. Halifax No studies have been done. Mississauga No analysis Calgary None available Edmonton No the City of Edm hasn’t done any dual left turn collision studies. Red Deer Signalized intersections with dual left turn lanes have been compared with signalized intersections without dual left turn lanes based on 10-year collisions statistics. Comparisons are based on the following measures: a. Red Deer’s left turn collision prediction model b. Total intersection collisions and rates, c. Total intersection fatal & injury collisions and rates, d. Total intersection left turn collisions and rates, e. Total intersection left turn fatal & injury collisions and rates, f. Intersection Collision Seventies type distribution g. Intersection Collision Temporal & Environnemental type distribution h. Intersection Collision Driver Action type distribution i. Intersection Collision Crash type distribution j. Before and after comparison for dual left turn lanes installation Wood Buffalo No recent Study Lethbridge Yes, through mission possible – 1 location Medicine Hat No Tucson Yes, the Manager of the Traffic Engineering Division did a study of the dual operations as his Master’s paper. We found that the accidents only increased slightly (approx one left turn accident per year per approach—he did not monitor total accidents), with a massive increase operational efficiency. The accident experience is far less than the accident increase we experience when we install a new signal.
What are the regulations regarding signage for dual left turns? Does your jurisdiction use TAC- standard signage? If so, which signs? If not, what are the standards your jurisdiction uses?
Oakville OTM Book #5 Pg.81 St. John’s Typical TAC-standard side-mounted multiple lane designation signs are used. RB-46L or RB-47L depending on the lane configuration. Halifax We use only TAC RB-46L and RB-47L. Mississauga Regulation – HTA Standard OTM Book 12 – “Left turn signal signs” Calgary In most cases, we use a single sign indicating dual turns by the display of two turn arrows on the sign. Edmonton TAC-standard signage is used in the City of Edmonton. The signs used are RB- 46L and RB-47L (600mmx600mm size) Red Deer The City uses TAC standard signage. If two RB-41L signs can be placed overhead, this is the preferred method. If not, a maximum of 3 RB-46L signs can be installed. One sign is installed on the opposite side of the intersection on
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an opposing median and the other two signs are installed on the median prior to the intersection at 5 and 25 metres from the nose of the median. If the bay length is less than 50 metres, a sign is not installed at the 25 metre distance. Wood Buffalo Use RB-46L on protected permissive dual left turns in advance at the turn and overhead on the signal arm Lethbridge TAC standard overhead is preferred but side mounted is used to reinforce. We use the RB(L) 46, 47. Medicine Hat Try to follow TAC-MUTCD. We use RB-46, combo of RB-44 with RB-41 over lanes, combo of RB-41 and RB-42 over lanes. Tucson In the United States we use the MUTCD standard dual arrows showing that a “U” turn is also OK. The same in New York, Denver and Texas.
What is the number of signal heads and display configuration that is typically used for dual left turn situations?
Oakville Two displays for every movement. Typically an auxiliary head is used for dual left operation unless it is a split phase configuration St. John’s For dual left turns at “quad” intersections with split phasing, two signal heads are used, one or both with flashing left turn arrows, depending on weather or not there is a shared through-left lane. At “quad” intersections where the dual left turn movement is protected-prohibited, a single signal head (with LED lamps and a backboard) is placed in the median – this signal head also has a sign directly below it that identifies it as a “Left Turn Signal”. Where dual left turns occurs at “T” intersections, two signal heads are used. At some locations both signals have steady green ball indicators while at others both signals have flashing green arrows instead of steady green balls. Halifax Split phasing – generally three 5-section heads: R / A / G / A< / G< Protected only phasing – Two 3-section left heads: R / A< / G< and two 3- section thru heads: R / A / G. Mississauga 2 – 3section 12 in sections Calgary Typically, one head with Red-Red-Amber-Green Arrow. Edmonton For an advanced protected/permissive dual left turn a single vertical fixture with 5 heads (R, A, G, solid amber arrow, flashing green arrow is used. For fully protected dual left turns, a single vertical fixture with 4 heads (R, R, solid amber arrow, flashing green arrow) is used. Delayed permissive/protected dual left turns are controlled by a single horizontal fixture with 4 heads (R, A, flashing green arrow, G). The City of Edmonton uses 8” fixtures, and 12” fixtures for speeds above 60km/h. Red Deer Typically, 1 median signal, one overhead signal and one far-right secondary signal are installed. Only the median signal displays the left-turn arrow. Where no median exists, the left-turn signal is mounted overhead, centered as near as possible in front of the left turn lane for which it is intended. Protected/Prohibited phasing display is Red Ball - Red Ball - Amber Ball - Green arrow. Wood Buffalo One signal head with amber arrow display for each turn lane vertical mounting Lethbridge Usually one per lane.
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Medicine Hat Primary R/A/GA flash Auxiliary R/A/GA/G flash/no flash Auxiliary R/A/GA/G flash (GA = Green Arrow) Tucson We use a minimum of two five-section signal heads R-Y-G-YA-GA
Are there any other criteria that you believe should be considered in developing appropriate signal phasing criteria for dual left turns?
Oakville No Response St. John’s No Response Halifax No Response Missassauga A standard, if not already implemented, regarding the installation of “Shadow” Lane for the opposing left turn lane which may not be dual should be developed. Calgary No Response Edmonton Consideration should be given to sight line limitations imposed by a dual left turn in the opposing direction. Red Deer No Response Wood Buffalo No Response Lethbridge No Response Medicine Hat No Response Tucson We have found that by off- setting the dual lefts by approx 4-6 feet and providing the same sight distance for the left turning driver in the second lane as they would have with a single left turn lane, the dual operation, permitted- protected, works very well.
Any other comments?
Edmonton Another row was added to Table 2.1: Inventory of Alternative Signal Phasing Locations because it did not contain a category for dual left turns that are protected due to intersection geometry (i.e. there is no opposing traffic direction that could conflict with the left turn). The City of Edmonton did not feel that this type of dual left turn really fit into any of the other category. Red Deer MUTCDC Section B4.4.2 Part A recommended left turn phasing when double left turns are permitted where there is an opposing through movement. This significantly hampers the efficiency of traffic movement at light traffic locations with double left turn lanes. Tucson If you would like pictures we would be glad to send some.
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On behalf of C-TEP and Earth Tech, thank you very much for taking the time to fill out this survey form. If you would be interested in the results of this study via email, please check the box below and include your name and email address.
Yes! I would like the results of this study.
Name: ______Email: ______
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Appendix B
City of Calgary Collision Analysis
Summary of Volumes for Calgary
Intersection: 14 Street SW & Anderson Road SW Intersection: Barlow Trail NE & 32 Avenue NE PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 465 698 557 202 441 15 6 1401 440 404 647 32 PM Peak Hour Volume = 180 700 165 182 1150 321 307 817 261 237 1087 277 Daily Volume = 5580 8376 6684 2424 5292 180 72 16812 5280 4848 7764 384 Daily Volume = 2160 8400 1980 2184 13800 3852 3684 9804 3132 2844 13044 3324 Total Approach Volume = 20640 7896 22164 12996 Total Approach Volume = 12540 19836 16620 19212 Total Volume = 63696 Total Volume = 68208
Intersection: Glenmore Trail SE & Barlow Trail SE Intersection: 36 Street SE & Memorial Drive SE PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 82 543 612 196 257 57 79 467 43 251 629 186 PM Peak Hour Volume = 370 643 371 256 531 220 341 1063 129 475 1301 269 Daily Volume = 984 6516 7344 2352 3084 684 948 5604 516 3012 7548 2232 Daily Volume = 4440 7716 4452 3072 6372 2640 4092 12756 1548 5700 15612 3228 Total Approach Volume = 14844 6120 7068 12792 Total Approach Volume = 16608 12084 18396 24540 Total Volume = 40824 Total Volume = 71628
Intersection: Crowchild Trail NW & Nosehill Drive NW Intersection: 17 Avenue SW & Sarcee Trail SW PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 402 957 231 206 797 320 439 776 588 425 42 47 PM Peak Hour Volume = 177 980 157 400 986 177 253 873 173 168 262 203 Daily Volume = 4824 11484 2772 2472 9564 3840 5268 9312 7056 5100 504 564 Daily Volume = 2124 11760 1884 4800 11832 2124 3036 10476 2076 2016 3144 2436 Total Approach Volume = 19080 15876 21636 6168 Total Approach Volume = 15768 18756 15588 7596 Total Volume = 62760 Total Volume = 57708
Intersection: Shaganappi Trail NW & Northland Drive NW Intersection: Barlow Trail NE & McKnight Blvd NE PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 284 520 157 391 1169 21 237 522 815 121 262 157 PM Peak Hour Volume = 249 359 252 601 733 767 258 908 158 267 1602 327 Daily Volume = 3408 6240 1884 4692 14028 252 2844 6264 9780 1452 3144 1884 Daily Volume = 2988 4308 3024 7212 8796 9204 3096 10896 1896 3204 19224 3924 Total Approach Volume = 11532 18972 18888 6480 Total Approach Volume = 10320 25212 15888 26352 Total Volume = 55872 Total Volume = 77772 Summary of Total Collision for Calgary
Intersection: 14 Street SW & Anderson Road SW Intersection: Barlow Trail NE & 32 Avenue NE Direction of vehicle (Total over 3 years) Direction of vehicle (Total over 3 years) Collision Type SB EB Collision Type NB SB NB WB Total EB WB Total (Dual) (Dual) (Dual) (Dual) 1 N/A N/A N/A N/A 0 1 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 3 years) 0 0 0 0 88 Total (over 3 years) 0 0 0 0 152 Total (per year) 0 0 0 0 29 Total (per year) 0 0 0 0 51
Intersection: Glenmore Trail SE & Barlow Trail SE Intersection: 36 Street SE & Memorial Drive SE Direction of vehicle (Total over 3 years) Direction of vehicle (Total over 3 years) Collision Type NB SB EB WB Collision Type NB SB EB WB Total Total (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) 1 N/A N/A N/A N/A 0 1 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 0 0 0 0 82 Total (over 3 years) 0 0 0 0 158 Total (per year) 0 0 0 0 27 Total (per year) 0 0 0 0 53
Intersection: Crowchild Trail NW & Nosehill Drive NW Intersection: 17 Avenue SW & Sarcee Trail SW Direction of vehicle (Total over 3 years) Direction of vehicle (Total over 3 years) Collision Type SB EB WB Collision Type EB WB NB Total NB SB Total (Dual) (Dual) (Dual) (Dual) (Dual) 1 N/A N/A N/A N/A 0 1 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 3 years) 0 0 0 0 104 Total (over 3 years) 0 0 0 0 158 Total (per year) 0 0 0 0 35 Total (per year) 0 0 0 0 53
Intersection: Shaganappi Trail NW & Northland Drive NW Intersection: Barlow Trail NE & McKnight Blvd NE Direction of vehicle (Total over 3 years) Direction of vehicle (Total over 3 years) Collision Type NB SB Collision Type NB SB EB WB EB WB Total Total (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) 1 N/A N/A N/A N/A 0 1 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 2 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 3 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 3 years) 0 0 0 0 100 Total (over 3 years) 0 0 0 0 152 Total (per year) 0 0 0 0 33 Total (per year) 0 0 0 0 51 Summary of Left Turn Collisions for Calgary
Intersection: 14 Street SW & Anderson Road SW Intersection: Barlow Trail NE & 32 Avenue NE Direction of vehicle making left turn (Total over 3 years) Direction of vehicle making left turn (Total over 3 years) Collision Type SB EB Collision Type NB SB NB WB Total EB WB Total (Dual) (Dual) (Dual) (Dual) 1 0 0 0 0 0 1 3 7 8 13 31 2 0 0 0 0 0 2 0 0 0 0 0 3 0 0 2 0 2 3 1 1 1 5 8 4 0 0 2 0 2 4 1 1 1 0 3 Total (over 3 years) 0 0 4 0 4 Total (over 3 years) 5 9 10 18 42 Total (per year) 0.0 0.0 1.3 0.0 1.3 Total (per year) 1.7 3.0 3.3 6.0 14.0
Intersection: Glenmore Trail SE & Barlow Trail SE Intersection: 36 Street SE & Memorial Drive SE Direction of vehicle making left turn (Total over 3 years) Direction of vehicle making left turn (Total over 3 years) Collision Type NB SB EB WB Collision Type NB SB EB WB Total Total (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) 1 0 0 2 0 2 1 0 1 1 3 5 2 0 1 0 0 1 2 1 0 0 1 2 3 0 1 0 1 2 3 0 2 7 1 10 4 0 1 1 0 2 4 0 2 0 1 3 Total (over 3 years) 0 3 3 1 7 Total (over 3 years) 1 5 8 6 20 Total (per year) 0.0 1.0 1.0 0.3 2.3 Total (per year) 0.3 1.7 2.7 2.0 6.7
Intersection: Crowchild Trail NW & Nosehill Drive NW Intersection: 17 Avenue SW & Sarcee Trail SW Direction of vehicle making left turn (Total over 3 years) Direction of vehicle making left turn (Total over 3 years) Collision Type SB EB WB Collision Type EB WB NB Total NB SB Total (Dual) (Dual) (Dual) (Dual) (Dual) 1 0 0 0 0 0 1 1 1 1 0 3 2 0 0 2 0 2 2 0 0 0 0 0 3 0 0 4 4 8 3 3 5 0 1 9 4 0 0 0 0 0 4 0 1 0 2 3 Total (over 3 years) 0 0 6 4 10 Total (over 3 years) 4 7 1 3 15 Total (per year) 0.0 0.0 2.0 1.3 3.3 Total (per year) 1.3 2.3 0.3 1.0 5.0
Intersection: Shaganappi Trail NW & Northland Drive NW Intersection: Barlow Trail NE & McKnight Blvd NE Direction of vehicle making left turn (Total over 3 years) Direction of vehicle making left turn (Total over 3 years) Collision Type NB SB Collision Type NB SB EB WB EB WB Total Total (Dual) (Dual) (Dual) (Dual) (Dual) (Dual) 1 1 1 5 4 11 1 0 0 2 1 3 2 0 2 0 0 2 2 0 0 0 0 0 3 1 5 1 2 9 3 0 0 3 2 5 4 0 3 0 0 3 4 0 0 0 0 0 Total (over 3 years) 2 11 6 6 25 Total (over 3 years) 0 0 5 3 8 Total (per year) 0.7 3.7 2.0 2.0 8.3 Total (per year) 0.0 0.0 1.7 1.0 2.7 Summary of Total Accident Rate and Hazard Index for Calgary
Intersection: 14 Street SW & Anderson Road SW Intersection: Crowchild Trail NW & Nosehill Drive NW Intersection: Barlow Trail NE & 32 Avenue NE Intersection: 17 Avenue SW & Sarcee Trail SW
Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Annual Accidents = 29.3 Annual Accidents = 34.7 Annual Accidents = 50.7 Annual Accidents = 52.7 Conflicting Daily Volume = 63696.0 Conflicting Daily Volume = 62760 Conflicting Daily Volume = 68208 Conflicting Daily Volume = 57708 Accident Rate = 1.3 Accident Rate = 1.513 Accident Rate = 2.035 Accident Rate = 2.500
Hazard Index = 4.605 Hazard Index = 5.524 Hazard Index = 7.428 Hazard Index = 9.126
Maximum v/c raito = 1.750 Maximum v/c raito = 1.290 Maximum v/c raito = 1.190 Maximum v/c raito = 2.330
Intersection: Glenmore Trial SE & Barlow Trail SE Intersection: Shaganappi Trail NW & Nosehill Drive NW Intersection: 36 Street SE & Memorial Drive SE Intersection: Barlow Trail NE & McKnight Blvd NE
Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Annual Accidents = 27.3 Annual Accidents = 33.3 Annual Accidents = 52.7 Annual Accidents = 50.7 Conflicting Daily Volume = 40824.0 Conflicting Daily Volume = 55872 Conflicting Daily Volume = 71628 Conflicting Daily Volume = 77772 Accident Rate = 1.834 Accident Rate = 1.635 Accident Rate = 2.014 Accident Rate = 1.785
Hazard Index = 6.695 Hazard Index = 5.966 Hazard Index = 7.353 Hazard Index = 6.515
Maximum v/c raito = 1.280 Maximum v/c raito = 0.000 Maximum v/c raito = 2.530 Maximum v/c raito = 1.780 Summary of Left Turn Accident Rate and Hazard Index for Calgary
Intersection: 14 Street SW & Anderson Road SW Intersection: Barlow Trail NE & 32 Avenue NE
Number of Dual Left Turns = 2 Number of Dual Left Turns = 2
Phasing Type = Split Phasing Type = Protected Phasing Type = Protected Phasing Type = Protected
SB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 0.0 Annual Accidents = 1.3 Annual Accidents = 1.7 Annual Accidents = 3.0 Conflicting Daily Volume = 10872 Conflicting Daily Volume = 10800 Conflicting Daily Volume = 15960 Conflicting Daily Volume = 10584 Accident Rate = 0.000 Accident Rate = 0.338 Accident Rate = 0.286 Accident Rate = 0.777
Hazard Index = 0.000 Hazard Index = 1.235 Hazard Index = 1.044 Hazard Index = 2.834
v/c Ratio for Left Turn= 1.320 v/c Ratio for Left Turn= 1.750 v/c Ratio for Left Turn= 0.450 v/c Ratio for Left Turn= 0.480
Intersection: Glenmore Trail SE & Barlow Trail SE Intersection: 36 Street SE & Memorial Drive SE
Number of Dual Left Turns = 4 Number of Dual Left Turns = 4
Phasing Type = Protected Phasing Type = Protected Phasing Type = Protected Phasing Type = Protected
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 0.0 Annual Accidents = 1.0 Annual Accidents = 0.3 Annual Accidents = 1.7 Conflicting Daily Volume = 4068 Conflicting Daily Volume = 8868 Conflicting Daily Volume = 10812 Conflicting Daily Volume = 10788 Accident Rate = 0.000 Accident Rate = 0.309 Accident Rate = 0.084 Accident Rate = 0.423
Hazard Index = 0.000 Hazard Index = 1.128 Hazard Index = 0.308 Hazard Index = 1.545
v/c Ratio for Left Turn= 0.680 v/c Ratio for Left Turn= 0.440 v/c Ratio for Left Turn= 1.290 v/c Ratio for Left Turn= 1.100
Phasing Type = Phasing Type = Phasing Type = Protected Phasing Type = Protected
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.0 Annual Accidents = 0.3 Annual Accidents = 2.7 Annual Accidents = 2.0 Conflicting Daily Volume = 8496 Conflicting Daily Volume = 8616 Conflicting Daily Volume = 19704 Conflicting Daily Volume = 18456 Accident Rate = 0.322 Accident Rate = 0.106 Accident Rate = 0.371 Accident Rate = 0.297
Hazard Index = 1.177 Hazard Index = 0.387 Hazard Index = 1.353 Hazard Index = 1.084
v/c Ratio for Left Turn= 0.730 v/c Ratio for Left Turn= 0.430 v/c Ratio for Left Turn= 0.950 v/c Ratio for Left Turn= 2.530 Summary of Left Turn Accident Rate and Hazard Index for Calgary
Intersection: Crowchild Trail NW & Nosehill Drive NW Intersection: 17 Avenue SW & Sarcee Trail SW
Number of Dual Left Turns = 3 Number of Dual Left Turns = 2
Phasing Type = Split Phasing Type = Split Phasing Type = Protected Phasing Type = Protected
SB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 0.0 Annual Accidents = 2.0 Annual Accidents = 0.3 Annual Accidents = 1.0 Conflicting Daily Volume = 14388 Conflicting Daily Volume = 13956 Conflicting Daily Volume = 6180 Conflicting Daily Volume = 12492 Accident Rate = 0.000 Accident Rate = 0.393 Accident Rate = 0.148 Accident Rate = 0.219
Hazard Index = 0.000 Hazard Index = 1.433 Hazard Index = 0.539 Hazard Index = 0.801
v/c Ratio for Left Turn= 1.290 v/c Ratio for Left Turn= 0.990 v/c Ratio for Left Turn= 0.890 v/c Ratio for Left Turn= 0.910
Phasing Type = Protected
WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.3 Conflicting Daily Volume = 5772 Accident Rate = 0.633
Hazard Index = 2.310
v/c Ratio for Left Turn= 1.020
Intersection: Shaganappi Trail NW & Northland Drive NW Intersection: Barlow Trail NE & McKnight Blvd NE
Number of Dual Left Turns = 2 Number of Dual Left Turns = 2
Phasing Type = Protected Phasing Type = Protected Phasing Type = Protected Phasing Type = Protected
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 0.7 Annual Accidents = 3.7 Annual Accidents = 0.0 Annual Accidents = 0.0 Conflicting Daily Volume = 17436 Conflicting Daily Volume = 10932 Conflicting Daily Volume = 11784 Conflicting Daily Volume = 11520 Accident Rate = 0.105 Accident Rate = 0.919 Accident Rate = 0.000 Accident Rate = 0.000
Hazard Index = 0.382 Hazard Index = 3.354 Hazard Index = 0.000 Hazard Index = 0.000
v/c Ratio for Left Turn= 0.000 v/c Ratio for Left Turn= 0.000 v/c Ratio for Left Turns = 1.240 v/c Ratio for Left Turn= 0.850
Phasing Type = Protected Phasing Type = Protected
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.7 Annual Accidents = 1.0 Conflicting Daily Volume = 22320 Conflicting Daily Volume = 14100 Accident Rate = 0.205 Accident Rate = 0.194
Hazard Index = 0.747 Hazard Index = 0.709
v/c Ratio for Left Turn= 0.760 v/c Ratio for Left Turn= 1.780 Intersection: Anderson Road SW & 14 Street SW CALGARY
Dual Left Turn Location(s): SB, EB
Phasing Type Lead/Lag North Split - South Split - Phasing Bar from synchro East Prot Lead West Prot Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 465 698 557 202 441 15 6 1401 440 404 647 32 Daily Volume = 5580 8376 6684 2424 5292 180 72 16812 5280 4848 7764 384 Total Volume = 20640 7896 22164 12996 Total Approach Volume = 63696
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 10872 10800 7836 21660 51168
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) SB EB SB EB Collision Type NB (Dual) (Dual) WB Total Collision Type NB (Dual) (Dual) WB Total 1 0 0 0 0 0 1 N/A N/A N/A N/A 0 2 0 0 0 0 0 2 N/A N/A N/A N/A 0 3 0 0 2 0 2 3 N/A N/A N/A N/A 0 4 0 0 2 0 2.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 0 0 4 0 4 Total (over 3 years) 0 0 0 0 88 Total (per year) 0.0 0.0 1.3 0.0 1.3 Total (per year) 0.0 0.0 0.0 0.0 29.3
SB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.0 Annual Accidents = 1.3 Annual Accidents = 29.3 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 10872 Conflicting Daily Volume = 10800 Conflicting Daily Volume = 63696 N/A (Information Not Available) Accident Rate = 0.000 Accident Rate = 0.338 Accident Rate = 1.262
Hazard Index = 0.000 Hazard Index = 1.235 Hazard Index = 4.605
v/c Ratio for Left Turns = 1.32 v/c Ratio for Left Turns = 1.75 Maximum v/c Ratio = 1.75
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.7 0.0 0.0 0.3 0.3 0.0 0.0 0.3 0.0 0.3 0.3 0.0 0.0 0.3 4 0.7 0.0 0.3 0.0 0.3 0.0 0.0 0.3 0.3 0.0 0.0 0.0 0.0 0.7 Total 1.3 0.0 0.3 0.3 0.7 0.0 0.0 0.7 0.3 0.3 0.3 0.0 0.0 1.0 Intersection: Glenmore Trail SE & Barlow Trail SE CALGARY
Dual Left Turn Location(s):
Phasing Type Lead/Lag North Protected Lead South Protected Lead Phasing Bar from synchro East Protected Lead West Protected Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 82 543 612 196 257 57 79 467 43 251 629 186 Daily Volume = 984 6516 7344 2352 3084 684 948 5604 516 3012 7548 2232 Total Volume = 14844 6120 7068 12792 Total Approach Volume = 40824
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 4068 8868 8496 8616 30048
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) NB SB EB WB NB SB EB WB Collision Type (Dual) (Dual) (Dual) (Dual) Total Collision Type (Dual) (Dual) (Dual) (Dual) Total 1 0 0 2 0 2 1 N/A N/A N/A N/A 0 2 0 1 0 0 1 2 N/A N/A N/A N/A 0 3 0 1 0 1 2 3 N/A N/A N/A N/A 0 4 0 1 1 0 2.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 0 3 3 1 7 Total (over 3 years) 0 0 0 0 82 Total (per year) 0.0 1.0 1.0 0.3 2.3 Total (per year) 0.0 0.0 0.0 0.0 27.3
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.0 Annual Accidents = 1.0 Annual Accidents = 27.3 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 4068 Conflicting Daily Volume = 8868 Conflicting Daily Volume = 40824 N/A (Information Not Available) Accident Rate = 0.000 Accident Rate = 0.309 Accident Rate = 1.834
Hazard Index = 0.000 Hazard Index = 1.128 Hazard Index = 6.695
v/c Ratio for Left Turns = 0.68 v/c Ratio for Left Turns = 0.44 Maximum v/c Ratio = 1.28
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.0 Annual Accidents = 0.3 Conflicting Daily Volume = 8496 Conflicting Daily Volume = 8616 Accident Rate = 0.322 Accident Rate = 0.106
Hazard Index = 1.177 Hazard Index = 0.387
v/c Ratio for Left Turns = 0.73 v/c Ratio for Left Turns = 0.43
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 0.7 0.3 0.0 0.0 0.3 0.3 0.0 0.0 0.0 0.3 0.0 0.3 0.0 0.3 2 0.3 0.0 0.3 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.3 0.0 0.0 3 0.7 0.0 0.7 0.0 0.0 0.0 0.3 0.3 0.0 0.0 0.0 0.0 0.3 0.3 4 0.7 0.3 0.3 0.0 0.0 0.3 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.7 Total 2.3 0.7 1.3 0.0 0.3 0.7 0.3 1.0 0.0 0.3 0.0 0.7 0.3 1.3 Intersection: Crowchild Trail and Nosehill Drive NW CALGARY
Dual Left Turn Location(s): SB, EB, WB
Phasing Type Lead/Lag North Split - South Split - Phasing Bar from synchro East Protected Lead West Protected Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 402 957 231 206 797 320 439 776 588 425 42 47 Daily Volume = 4824 11484 2772 2472 9564 3840 5268 9312 7056 5100 504 564 Total Volume = 19080 15876 21636 6168 Total Approach Volume = 62760
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 14388 13956 5772 14412 48528
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) SB EB WB SB EB WB Collision Type NB (Dual) (Dual) (Dual) Total Collision Type NB (Dual) (Dual) (Dual) Total 1 0 0 0 0 0 1 N/A N/A N/A N/A 0 2 0 0 2 0 2 2 N/A N/A N/A N/A 0 3 0 0 4 4 8 3 N/A N/A N/A N/A 0 4 0 0 0 0 0.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 0 0 6 4 10 Total (over 3 years) 0 0 0 0 104 Total (per year) 0.0 0.0 2.0 1.3 3.3 Total (per year) 0.0 0.0 0.0 0.0 34.7
SB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.0 Annual Accidents = 2.0 Annual Accidents = 34.7 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 14388 Conflicting Daily Volume = 13956 Conflicting Daily Volume = 62760 N/A (Information Not Available) Accident Rate = 0.000 Accident Rate = 0.393 Accident Rate = 1.513
Hazard Index = 0.000 Hazard Index = 1.433 Hazard Index = 5.524
v/c Ratio for Left Turns = 1.29 v/c Ratio for Left Turns = 0.99 Maximum v/c Ratio = 1.29
WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.3 Conflicting Daily Volume = 5772 Accident Rate = 0.633
Hazard Index = 2.310
v/c Ratio for Left Turns = 1.02
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.7 0.0 0.3 0.0 0.3 0.0 0.0 0.3 0.0 0.3 0.0 0.3 0.0 0.3 3 2.7 0.3 0.7 0.7 1.0 0.0 0.0 0.7 0.7 1.3 0.7 1.0 0.3 0.7 4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Total 3.3 0.3 1.0 0.7 1.3 0.0 0.0 1.0 0.7 1.7 0.7 1.3 0.3 1.0 Intersection: Northland Drive and Shaganappi Trail NW CALGARY
Dual Left Turn Location(s):
Phasing Type Lead/Lag North South Phasing Bar from synchro East West
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 284 520 157 391 1169 21 237 522 815 121 262 157 Daily Volume = 3408 6240 1884 4692 14028 252 2844 6264 9780 1452 3144 1884 Total Volume = 11532 18972 18888 6480 Total Approach Volume = 55872
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 17436 10932 5988 7716 42072
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) NB SB NB SB Collision Type (Dual) (Dual) EB WB Total Collision Type (Dual) (Dual) EB WB Total 1 1 1 5 4 11 1 N/A N/A N/A N/A 0 2 0 2 0 0 2 2 N/A N/A N/A N/A 0 3 1 5 1 2 9 3 N/A N/A N/A N/A 0 4 0 3 0 0 3.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 2 11 6 6 25 Total (over 3 years) 0 0 0 0 100 Total (per year) 0.7 3.7 2.0 2.0 8.3 Total (per year) 0.0 0.0 0.0 0.0 33.3
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.7 Annual Accidents = 3.7 Annual Accidents = 33.3 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 17436 Conflicting Daily Volume = 10932 Conflicting Daily Volume = 55872 N/A (Information Not Available) Accident Rate = 0.105 Accident Rate = 0.919 Accident Rate = 1.635
Hazard Index = 0.382 Hazard Index = 3.354 Hazard Index = 5.966
v/c Ratio for Left Turns = v/c Ratio for Left Turns = Maximum v/c Ratio =
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 3.7 0.3 2.3 0.3 0.7 0.0 0.0 1.3 0.3 2.0 0.7 0.3 1.7 1.0 2 0.7 0.3 0.0 0.0 0.3 0.0 0.0 0.7 0.0 0.0 0.3 0.0 1.0 0.0 3 3.0 0.0 2.0 0.7 0.3 0.0 0.3 1.7 0.7 0.3 1.3 0.7 0.3 0.7 4 1.0 0.0 0.3 0.0 0.7 0.0 0.0 0.3 0.0 0.7 0.3 0.7 0.0 0.0 Total 8.3 0.7 4.7 1.0 2.0 0.0 0.3 4.0 1.0 3.0 2.7 1.7 3.0 1.7 Intersection: Barlow Trail and 32 Avenue NE CALGARY
Dual Left Turn Location(s): NB, SB
Phasing Type Lead/Lag North Protected Lag South Protected Lag Phasing Bar from synchro East Protected Lead West Protected Lag
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 180 700 165 182 1150 321 307 817 261 237 1087 277 Daily Volume = 2160 8400 1980 2184 13800 3852 3684 9804 3132 2844 13044 3324 Total Volume = 12540 19836 16620 19212 Total Approach Volume = 68208
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 15960 10584 16728 12648 55920
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) NB SB NB SB Collision Type (Dual) (Dual) EB WB Total Collision Type (Dual) (Dual) EB WB Total 1 3 7 8 13 31 1 N/A N/A N/A N/A 0 2 0 0 0 0 0 2 N/A N/A N/A N/A 0 3 1 1 1 5 8 3 N/A N/A N/A N/A 0 4 1 1 1 0 3.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 5 9 10 18 42 Total (over 3 years) 0 0 0 0 152 Total (per year) 1.7 3.0 3.3 6.0 14.0 Total (per year) 0.0 0.0 0.0 0.0 50.7
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 1.7 Annual Accidents = 3.0 Annual Accidents = 50.7 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 15960 Conflicting Daily Volume = 10584 Conflicting Daily Volume = 68208 N/A (Information Not Available) Accident Rate = 0.286 Accident Rate = 0.777 Accident Rate = 2.035
Hazard Index = 1.044 Hazard Index = 2.834 Hazard Index = 7.428
v/c Ratio for Left Turns = 0.45 v/c Ratio for Left Turns = 0.48 Maximum v/c Ratio = 1.19
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 10.3 2.3 5.3 1.0 1.3 0.0 2.0 2.3 1.3 4.7 2.0 1.7 2.3 4.3 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 2.7 0.3 1.0 1.3 0.0 0.0 0.0 0.7 2.0 0.0 0.7 0.3 1.0 0.7 4 1.0 0.0 0.3 0.7 0.0 0.0 0.3 0.0 0.3 0.3 0.0 0.0 1.0 0.0 Total 14.0 2.7 6.7 3.0 1.3 0.0 2.3 3.0 3.7 5.0 2.7 2.0 4.3 5.0 Intersection: Memorial Drive and 36th Street E CALGARY
Dual Left Turn Location(s): NB, SB, EB, WB
Phasing Type Lead/Lag North Protected Lead South Protected Lead Phasing Bar from synchro East Protected Lead West Protected Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 370 643 371 256 531 220 341 1063 129 475 1301 269 Daily Volume = 4440 7716 4452 3072 6372 2640 4092 12756 1548 5700 15612 3228 Total Volume = 16608 12084 18396 24540 Total Approach Volume = 71628
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 10812 10788 19704 18456 59760
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) NB SB EB WB NB SB EB WB Collision Type (Dual) (Dual) (Dual) (Dual) Total Collision Type (Dual) (Dual) (Dual) (Dual) Total 1 0 1 1 3 5 1 N/A N/A N/A N/A 0 2 1 0 0 1 2 2 N/A N/A N/A N/A 0 3 0 2 7 1 10 3 N/A N/A N/A N/A 0 4 0 2 0 1 3.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 1 5 8 6 20 Total (over 3 years) 0 0 0 0 158 Total (per year) 0.3 1.7 2.7 2.0 6.7 Total (per year) 0.0 0.0 0.0 0.0 52.7
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.3 Annual Accidents = 1.7 Annual Accidents = 52.7 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 10812 Conflicting Daily Volume = 10788 Conflicting Daily Volume = 71628 N/A (Information Not Available) Accident Rate = 0.084 Accident Rate = 0.423 Accident Rate = 2.014
Hazard Index = 0.308 Hazard Index = 1.545 Hazard Index = 7.353
v/c Ratio for Left Turns = 1.29 v/c Ratio for Left Turns = 1.1 Maximum v/c Ratio = 2.53
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 2.7 Annual Accidents = 2.0 Conflicting Daily Volume = 19704 Conflicting Daily Volume = 18456 Accident Rate = 0.371 Accident Rate = 0.297
Hazard Index = 1.353 Hazard Index = 1.084
v/c Ratio for Left Turns = 0.95 v/c Ratio for Left Turns = 2.53
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 1.7 0.0 0.7 0.3 0.7 0.3 0.0 0.3 0.0 1.0 0.3 0.3 0.3 1.0 2 0.7 0.3 0.3 0.0 0.0 0.0 0.0 0.3 0.3 0.0 0.3 0.0 0.0 0.0 3 3.3 0.3 2.0 0.0 1.0 0.0 0.3 1.0 1.0 1.0 1.3 0.7 0.3 0.3 4 1.0 0.7 0.3 0.0 0.0 0.0 0.0 0.3 0.0 0.7 0.3 0.0 0.3 0.0 Total 6.7 1.3 3.3 0.3 1.7 0.3 0.3 2.0 1.3 2.7 2.3 1.0 1.0 1.3 Intersection: 17th Avenue and Sarcee Trail SW CALGARY
Dual Left Turn Location(s): EB, WB
Phasing Type Lead/Lag North Protected Lead South Protected Lead Phasing Bar from synchro East Protected Lag West Protected Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 177 980 157 400 986 177 253 873 173 168 262 203 Daily Volume = 2124 11760 1884 4800 11832 2124 3036 10476 2076 2016 3144 2436 Total Volume = 15768 18756 15588 7596 Total Approach Volume = 57708
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 13956 16560 6180 12492 49188
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) EB WB EB WB Collision Type NB SB (Dual) (Dual) Total Collision Type NB SB (Dual) (Dual) Total 1 1 1 1 0 3 1 N/A N/A N/A N/A 0 2 0 0 0 0 0 2 N/A N/A N/A N/A 0 3 3 5 0 1 9 3 N/A N/A N/A N/A 0 4 0 1 0 2 3.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 4 7 1 3 15 Total (over 3 years) 0 0 0 0 158 Total (per year) 1.3 2.3 0.3 1.0 5.0 Total (per year) 0.0 0.0 0.0 0.0 52.7
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.3 Annual Accidents = 1.0 Annual Accidents = 52.7 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 6180 Conflicting Daily Volume = 12492 Conflicting Daily Volume = 57708 N/A (Information Not Available) Accident Rate = 0.148 Accident Rate = 0.219 Accident Rate = 2.500
Hazard Index = 0.539 Hazard Index = 0.801 Hazard Index = 9.126
v/c Ratio for Left Turns = 0.89 v/c Ratio for Left Turns = 0.91 Maximum v/c Ratio = 2.33
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 1.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.3 0.7 0.0 0.0 0.7 0.3 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 3.0 0.7 1.3 0.3 1.0 0.0 1.0 1.0 0.3 0.7 1.0 0.3 0.7 1.0 4 1.0 0.0 0.7 0.3 0.0 0.0 0.0 0.0 0.3 0.7 0.3 0.0 0.3 0.3 Total 5.0 0.7 3.0 0.7 1.0 0.0 1.0 1.0 1.0 2.0 1.3 0.3 1.7 1.7 Intersection: McKnight Blvd and Barlow Trail NE CALGARY
Dual Left Turn Location(s): NB, EB, SB, WB
Phasing Type Lead/Lag North Protected Lead South Protected Lag Phasing Bar from synchro East Protected Lead West Protected Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 249 359 252 601 733 767 258 908 158 267 1602 327 Daily Volume = 2988 4308 3024 7212 8796 9204 3096 10896 1896 3204 19224 3924 Total Volume = 10320 25212 15888 26352 Total Approach Volume = 77772
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Left Conflicting Volume 11784 11520 22320 14100 59724
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 3 years) Direction of vehicle (Total over 3 years) NB SB EB WB NB SB EB WB Collision Type (Dual) (Dual) (Dual) (Dual) Total Collision Type (Dual) (Dual) (Dual) (Dual) Total 1 0 0 2 1 3 1 N/A N/A N/A N/A 0 2 0 0 0 0 0 2 N/A N/A N/A N/A 0 3 0 0 3 2 5 3 N/A N/A N/A N/A 0 4 0 0 0 0 0.0 4 N/A N/A N/A N/A 0.0 Total (over 3 years) 0 0 5 3 8 Total (over 3 years) 0 0 0 0 152 Total (per year) 0.0 0.0 1.7 1.0 2.7 Total (per year) 0.0 0.0 0.0 0.0 50.7
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 0.0 Annual Accidents = 0.0 Annual Accidents = 50.7 Annual accidents averaged for years 2000 to 2002 inclusive Conflicting Daily Volume = 11784 Conflicting Daily Volume = 11520 Conflicting Daily Volume = 77772 N/A (Information Not Available) Accident Rate = 0.000 Accident Rate = 0.000 Accident Rate = 1.785
Hazard Index = 0.000 Hazard Index = 0.000 Hazard Index = 6.515
v/c Ratio for Left Turns = 1.24 v/c Ratio for Left Turns = 0.85 Maximum v/c Ratio = 1.78
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.7 Annual Accidents = 1.0 Conflicting Daily Volume = 22320 Conflicting Daily Volume = 14100 Accident Rate = 0.205 Accident Rate = 0.194
Hazard Index = 0.747 Hazard Index = 0.709
v/c Ratio for Left Turns = 0.76 v/c Ratio for Left Turns = 1.78
Annual Accidents (Involving Left Turns only) Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 1.0 0.0 0.3 0.7 0.0 0.0 0.7 0.0 0.0 0.3 0.7 0.0 0.0 0.3 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 1.7 0.3 0.3 0.3 0.7 0.0 0.3 0.3 0.0 1.0 0.7 0.3 0.0 0.7 4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Total 2.7 0.3 0.7 1.0 0.7 0.0 1.0 0.3 0.0 1.3 1.3 0.3 0.0 1.0
Appendix C
City of Edmonton Collision Analysis
Summary of Volumes for Edmonton
Intersection: 23 Avenue and Calgary Trail Intersection: 87 Avenue and 178 Street PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 351 1773 617 372 1739 150 273 767 425 229 610 124 PM Peak Hour Volume = 162 1230 247 172 1032 173 274 350 211 122 272 92 Daily Volume = 4212 21276 7404 4464 20868 1800 3276 9204 5100 2748 7320 1488 Daily Volume = 1944 14760 2964 2064 12384 2076 3288 4200 2532 1464 3264 1104 Total Volume = 32892 27132 17580 11556 Total Volume = 19668 16524 10020 5832 Total Volume = 89160 Total Volume = 52044
Intersection: Yellowhead Trail and 127 Street Intersection: Argyll Road and 75 Street PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 90 563 459 0 992 37 0 2434 509 762 2590 29 PM Peak Hour Volume = 35 1097 211 52 1148 466 384 499 34 579 931 224 Daily Volume = 1080 6756 5508 0 11904 444 0 29208 6108 9144 31080 348 Daily Volume = 420 13164 2532 624 13776 5592 4608 5988 408 6948 11172 2688 Total Volume = 13344 12348 35316 40572 Total Volume = 16116 19992 11004 20808 Total Volume = 101580 Total Volume = 67920
Intersection: 118 Avenue and 97 Street Intersection: Kingsway Avenue and 109 Street PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 60 658 572 0 2013 69 2 372 190 662 461 10 PM Peak Hour Volume = 47 786 84 716 908 31 0 799 53 93 557 308 Daily Volume = 720 7896 6864 0 24156 828 24 4464 2280 7944 5532 120 Daily Volume = 564 9432 1008 8592 10896 372 0 9588 636 1116 6684 3696 Total Volume = 15480 24984 6768 13596 Total Volume = 11004 19860 10224 11496 Total Volume = 60828 Total Volume = 52584
Intersection: 137 Avenue and 127 Street Intersection: University Avenue and 114 Street PM Peak to 24 hr Factor = 12 PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 132 526 327 222 1118 230 184 714 184 662 1245 91 PM Peak Hour Volume = 0 1044 34 850 475 247 379 346 26 24 438 1034 Daily Volume = 1584 6312 3924 2664 13416 2760 2208 8568 2208 7944 14940 1092 Daily Volume = 0 12528 408 10200 5700 2964 4548 4152 312 288 5256 12408 Total Volume = 11820 18840 12984 23976 Total Volume = 12936 18864 9012 17952 Total Volume = 67620 Total Volume = 12936
Intersection: 137 Avenue and 97 Street PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 142 770 210 301 2015 271 270 673 215 357 939 167 Daily Volume = 1704 9240 2520 3612 24180 3252 3240 8076 2580 4284 11268 2004 Total Volume = 13464 31044 13896 17556 Total Volume = 75960 Summary of Total Collision for Edmonton
Intersection: 23 Avenue and Calgary Trail Intersection: 87 Avenue and 178 Street Direction of vehicle (Total over 5 years) Direction of vehicle (Total over 5 years) Collision Type NB SB EB WB Collision Type WB Total NB SB EB Total (Dual) (Dual) (Dual) (Dual) (Dual) 1 1 2 9 30 42 1 6 9 10 13 38 2 1 3 7 8 19 2 2 5 4 21 32 3 95 78 35 60 268 3 39 16 10 26 91 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 97 83 51 98 329 Total (over 5 years) 47 30 24 60 161 Total (per year) 19.4 16.6 10.2 19.6 65.8 Total (per year) 9.4 6 4.8 12 32.2
Intersection: Yellowhead Trail and 127 Street Intersection: Argyll Road and 75 Street Direction of vehicle (Total over 5 years) Direction of vehicle (Total over 5 years) Collision Type SB EB Collision Type EB WB NB WB Total NB SB Total (Dual) (Dual) (Dual) (Dual) 1 5 20 1 4 30 1 6 5 14 16 41 2 9 9 2 2 22 2 7 3 2 3 15 3 17 70 45 71 203 3 54 71 15 5 145 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 31 99 48 77 255 Total (over 5 years) 67 79 31 24 201 Total (per year) 6.2 19.8 9.6 15.4 51 Total (per year) 13.4 15.8 6.2 4.8 40.2
Intersection: 118 Avenue and 97 Street Intersection: Kingsway Avenue and 109 Street Direction of vehicle (Total over 5 years) Direction of vehicle (Total over 5 years) Collision Type EB Collision Type NB NB SB WB Total SB EB WB Total (Dual) (Dual) 1 8 23 25 3 59 1 24 12 3 2 41 2 4 4 6 8 22 2 7 5 5 1 18 3 11 38 15 4 68 3 12 8 10 2 32 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 23 65 46 15 149 Total (over 5 years) 43 25 18 5 91 Total (per year) 4.6 13 9.2 3 29.8 Total (per year) 8.6 5 3.6 1 18.2
Intersection: 137 Avenue and 127 Street Intersection: University Avenue and 114 Street Direction of vehicle (Total over 5 years) Direction of vehicle (Total over 5 years) Collision Type EB WB Collision Type NB NB SB Total SB EB WB Total (Dual) (Dual) (Dual) 1 2 2 24 16 44 1 38 7 4 14 63 2 5 3 1 5 14 2 2 4 1 6 13 3 28 23 16 20 87 3 24 11 48 21 104 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 35 28 41 41 145 Total (over 5 years) 64 22 53 41 180 Total (per year) 7 5.6 8.2 8.2 29 Total (per year) 12.8 4.4 10.6 8.2 36
Intersection: 137 Avenue and 97 Street Direction of vehicle (Total over 5 years) Collision Type NB EB WB SB Total (Dual) (Dual) (Dual) 1 27 26 14 22 89 2 11 8 5 9 33 3 70 62 38 32 202 4 N/A N/A N/A N/A 0 Total (over 5 years) 108 96 57 63 324 Total (per year) 21.6 19.2 11.4 12.6 64.8 Summary of Left Turn Collisions for Edmonton
Intersection: 23 Avenue and Calgary Trail Intersection: 87 Avenue and 178 Street Direction of vehicle making left turn (Total over 5 years) Direction of vehicle making left turn (Total over 5 years) Collision Type NB SB EB WB Collision Type WB Total NB SB EB Total (Dual) (Dual) (Dual) (Dual) (Dual) 1 1 2 8 30 41 1 3 8 7 11 29 2 0 1 1 3 5 2 0 0 0 0 0 3 4 6 2 2 14 3 1 0 2 4 7 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 5 9 11 35 60 Total (over 5 years) 4 8 9 15 36 Total (per year) 1 1.8 2.2 7 12 Total (per year) 0.8 1.6 1.8 3 7.2
Intersection: Yellowhead Trail and 127 Street Intersection: Argyll Road and 75 Street Direction of vehicle making left turn (Total over 5 years) Direction of vehicle making left turn (Total over 5 years) Collision Type SB EB Collision Type EB WB NB WB Total NB SB Total (Dual) (Dual) (Dual) (Dual) 1 4 16 1 2 23 1 6 5 14 16 41 2 1 1 0 0 2 2 2 0 0 1 3 3 0 4 6 0 10 3 0 2 2 2 6 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 5 21 7 2 35 Total (over 5 years) 8 7 16 19 50 Total (per year) 1 4.2 1.4 0.4 7 Total (per year) 1.6 1.4 3.2 3.8 10
Intersection: 118 Avenue and 97 Street Intersection: Kingsway Avenue and 109 Street Direction of vehicle making left turn (Total over 5 years) Direction of vehicle making left turn (Total over 5 years) Collision Type EB Collision Type NB EB NB SB WB Total SB WB Total (Dual) (Dual) (Dual) 1 5 22 23 3 53 1 16 11 3 2 32 2 0 0 0 0 0 2 0 0 0 0 0 3 0 3 3 0 6 3 1 1 1 0 3 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 5 25 26 3 59 Total (over 5 years) 17 12 4 2 35 Total (per year) 1 5 5.2 0.6 11.8 Total (per year) 3.4 2.4 0.8 0.4 7
Intersection: 137 Avenue and 127 Street Intersection: University Avenue and 114 Street Direction of vehicle making left turn (Total over 5 years) Direction of vehicle making left turn (Total over 5 years) Collision Type EB WB Collision Type NB NB SB Total SB EB WB Total (Dual) (Dual) (Dual) 1 0 2 18 13 33 1 28 4 2 12 46 2 0 0 0 0 0 2 1 0 1 1 3 3 4 3 0 2 9 3 3 0 0 6 9 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 4 5 18 15 42 Total (over 5 years) 32 4 3 19 58 Total (per year) 0.8 1 3.6 3 8.4 Total (per year) 6.4 0.8 0.6 3.8 11.6
Intersection: 137 Avenue and 97 Street Direction of vehicle making left turn (Total over 5 years) Collision Type NB EB WB SB Total (Dual) (Dual) (Dual) 1 23 24 12 20 79 2 1 0 1 2 4 3 5 4 2 5 16 4 N/A N/A N/A N/A 0 Total (over 5 years) 29 28 15 27 99 Total (per year) 5.8 5.6 3 5.4 19.8 Summary of Total Accident Rate and Hazard Index for Edmonton
Intersection: 23 Avenue and Calgary Trail Intersection: 87 Avenue and 178 Street
Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Annual Accidents = 65.8 Annual Accidents = 32.2 Conflicting Daily Volume = 89160 Conflicting Daily Volume = 52044 Accident Rate = 2.022 Accident Rate = 1.695
Hazard Index = 7.380 Hazard Index = 6.187
Maximum v/c Ratio = 1.040 Maximum v/c Ratio = 0.930
Intersection: Yellowhead Trail and 127 Street Intersection: Argyll Road and 75 Street
Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Annual Accidents = 51.0 Annual Accidents = 40.2 Conflicting Daily Volume = 101580 Conflicting Daily Volume = 67920 Accident Rate = 1.376 Accident Rate = 1.622
Hazard Index = 5.021 Hazard Index = 5.919
Maximum v/c Ratio = 1.260 Maximum v/c Ratio = 0.920
Intersection: 118 Avenue and 97 Street Intersection: Kingsway Avenue and 109 Street
Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Annual Accidents = 29.8 Annual Accidents = 18.2 Conflicting Daily Volume = 60828 Conflicting Daily Volume = 52584 Accident Rate = 1.342 Accident Rate = 0.948
Hazard Index = 4.899 Hazard Index = 3.461
Maximum v/c Ratio = 1.030 Maximum v/c Ratio = 1.160
Intersection: 137 Avenue and 127 Street Intersection: University Avenue and 114 Street
Accident Rate (per million vehicles entry) Accident Rate (per million vehicles entry) Annual Accidents = 29.0 Annual Accidents = 36.0 Conflicting Daily Volume = 67620 Conflicting Daily Volume = 58764 Accident Rate = 1.175 Accident Rate = 1.678
Hazard Index = 4.289 Hazard Index = 6.126
Maximum v/c Ratio = 0.990 Maximum v/c Ratio = 2.190
Intersection: 137 Avenue and 97 Street
Accident Rate (per million vehicles entry) Annual Accidents = 64.8 Conflicting Daily Volume = 75960 Accident Rate = 2.337
Hazard Index = 8.531
Maximum v/c Ratio = 1.040 Summary of Left Turn Accident Rate and Hazard Index for Edmonton
Intersection: 23 Avenue and Calgary Trail
Number of Dual Left Turns = 4
Phasing Type = Protected Phasing Type = Protected
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 1.0 Annual Accidents = 1.8 Conflicting Daily Volume = 25080 Conflicting Daily Volume = 25740 Accident Rate = 0.109 Accident Rate = 0.192
Hazard Index = 0.399 Hazard Index = 0.699
v/c Ratio for Left Turns = 0.820 v/c Ratio for Left Turns = 0.800
Phasing Type = Prot + Perm Phasing Type = Prot + Perm
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 2.2 Annual Accidents = 7.0 Conflicting Daily Volume = 10596 Conflicting Daily Volume = 11952 Accident Rate = 0.569 Accident Rate = 1.605
Hazard Index = 2.076 Hazard Index = 5.857
v/c Ratio for Left Turns = 0.760 v/c Ratio for Left Turns = 0.790
Intersection: Yellowhead Trail and 127 Street
Number of Dual Left Turns = 2
Phasing Type = Permitted Phasing Type = Prot + Perm
SB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 4.2 Annual Accidents = 1.4 Conflicting Daily Volume = 6756 Conflicting Daily Volume = 31080 Accident Rate = 1.703 Accident Rate = 0.123
Hazard Index = 6.217 Hazard Index = 0.450
v/c Ratio for Left Turns = 0.940 v/c Ratio for Left Turns = 0.950
Intersection: 118 Avenue and 97 Street
Number of Dual Left Turns = 1
Phasing Type = Prot + Perm
EB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 5.2 Conflicting Daily Volume = 5556 Accident Rate = 2.564
Hazard Index = 9.359
v/c Ratio for Left Turns = 0.790
Intersection: 137 Avenue and 127 Street
Number of Dual Left Turns = 2
Phasing Type = Prot + Perm Phasing Type = Prot + Perm
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 3.6 Annual Accidents = 3.0 Conflicting Daily Volume = 17148 Conflicting Daily Volume = 16512.0 Accident Rate = 0.575 Accident Rate = 0.498
Hazard Index = 2.099 Hazard Index = 1.817
v/c Ratio for Left Turns = 0.990 v/c Ratio for Left Turns = 0.550 Summary of Left Turn Accident Rate and Hazard Index for Edmonton
Intersection: 137 Avenue and 97 Street
Number of Dual Left Turns = 3
Phasing Type = Prot + Perm Phasing Type = Prot + Perm
NB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 19.8 Annual Accidents = 3.0 Conflicting Daily Volume = 25884 Conflicting Daily Volume = 14508.0 Accident Rate = 2.096 Accident Rate = 0.567
Hazard Index = 7.650 Hazard Index = 2.068
v/c Ratio for Left Turns = 0.530 v/c Ratio for Left Turns = 0.850
Phasing Type = Prot + Perm
WB Dual Left Turn Accident Rate (per million vehicles entry)
Annual Accidents = 5.4 Conflicting Daily Volume = 12360 Accident Rate = 1.197
Hazard Index = 4.369
v/c Ratio for Left Turns = 0.840
Intersection: 87 Avenue and 178 Street
Number of Dual Left Turns = 1
Phasing Type = Prot + Perm
WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 3.0 Conflicting Daily Volume = 5664 Accident Rate = 1.451
Hazard Index = 5.297
v/c Ratio for Left Turns = 0.460
Intersection: Argyll Road and 75 Street
Number of Dual Left Turns = 2
Phasing Type = Prot + Perm Phasing Type = Prot + Perm
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 3.2 Annual Accidents = 3.8 Conflicting Daily Volume = 15780 Conflicting Daily Volume = 12936 Accident Rate = 0.556 Accident Rate = 0.805
Hazard Index = 2.028 Hazard Index = 2.938
v/c Ratio for Left Turns = 0.750 v/c Ratio for Left Turns = 0.840 Summary of Left Turn Accident Rate and Hazard Index for Edmonton
Intersection: Kingsway Avenue and 109 Street
Number of Dual Left Turns = 2 1 Phasing Type = Prot + Perm
NB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 3.4 Conflicting Daily Volume = 11460 Accident Rate = 0.813
Hazard Index = 2.967
v/c Ratio for Left Turns = 0.940
Intersection: University Avenue and 114 Street
Number of Dual Left Turns = 1
Phasing Type = Prot + Perm
NB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 6.4 Conflicting Daily Volume = 5700 Accident Rate = 3.076
Hazard Index = 11.228
v/c Ratio for Left Turns = 1.230 Intersection: 23 Avenue and Calgary Trail EDMONTON
Dual Left Turn Location(s): NB Left, SB Left, EB Left, WB Left
Phasing Type Lead/Lag North Protected Lead South Protected Lead Phasing Bar from synchro East Prot + Perm Lead West Prot + Perm Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 351 1773 617 372 1739 150 273 767 425 229 610 124 Daily Volume = 4212 21276 7404 4464 20868 1800 3276 9204 5100 2748 7320 1488 Total Volume = 32892 27132 17580 11556 Total Approach Volume = 89160
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume 25080 25740 10596 11952 73368
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) NB SB EB WB NB SB EB WB Collision Type (Dual) (Dual) (Dual) (Dual) Total Collision Type (Dual) (Dual) (Dual) (Dual) Total 1 1 2 8 30 41 1 1 2 9 30 42 2 0 1 1 3 5 2 1 3 7 8 19 3 4 6 2 2 14 3 95 78 35 60 268 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 5 9 11 35 60 Total (over 5 years) 97 83 51 98 329 Total (per year) 1 1.8 2.2 7 12 Total (per year) 19.4 16.6 10.2 19.6 65.8
NB Dual Left Turn Accident Rate (per million vehicles entry) SB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 1.0 Annual Accidents = 1.8 Annual Accidents = 65.8 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 25080 Conflicting Daily Volume = 25740 Conflicting Daily Volume = 89160 N/A (Information Not Available) Accident Rate = 0.109 Accident Rate = 0.192 Accident Rate = 2.022
Hazard Index = 0.399 Hazard Index = 0.699 Hazard Index = 7.380
v/c Ratio for Left Turns = 0.82 v/c Ratio for Left Turns = 0.80 Maximum v/c Ratio = 1.04
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 2.2 Annual Accidents = 7.0 Conflicting Daily Volume = 10596 Conflicting Daily Volume = 11952 Accident Rate = 0.569 Accident Rate = 1.605
Hazard Index = 2.076 Hazard Index = 5.857
v/c Ratio for Left Turns = 0.76 v/c Ratio for Left Turns = 0.79
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 8.4 1.0 3.2 1.2 12.4 0.4 1.6 1.4 2.0 3.0 2.0 1.2 2.2 2.6 2 3.8 0.8 1.0 1.2 9.8 0.2 0.8 1.6 0.4 0.8 0.2 0.6 0.8 2.2 3 59.0 6.2 21.8 11.4 19.6 0.6 2.2 20.4 18.6 17.2 17.6 9.8 13.8 13.7 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 71.2 8.0 26.0 13.8 41.8 1.2 4.6 23.4 21.0 21.0 19.8 11.6 16.8 18.5 Intersection: Yellowhead Trail and 127 Street EDMONTON
Dual Left Turn Location(s): SB Left, EB Left
Phasing Type Lead/Lag North Permitted South Permitted Phasing Bar from synchro East Prot + Perm Lag West Permitted
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 90 563 459 0 992 37 0 2434 509 762 2590 29 Daily Volume = 1080 6756 5508 0 11904 444 0 29208 6108 9144 31080 348 Total Volume = 13344 12348 35316 40572 Total Approach Volume = 101580
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume - 6756 31080 - 37836
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) SB EB SB EB Collision Type NB (Dual) (Dual) WB Total Collision Type NB (Dual) (Dual) WB Total 1 4 16 1 2 23 1 5 20 1 4 30 2 1 1 0 0 2 2 9 9 2 2 22 3 0 4 6 0 10 3 17 70 45 71 203 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 5 21 7 2 35 Total (over 5 years) 31 99 48 77 255 Total (per year) 1 4.2 1.4 0.4 7 Total (per year) 6.2 19.8 9.6 15.4 51
SB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 4.2 Annual Accidents = 1.4 Annual Accidents = 51.0 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 6756 Conflicting Daily Volume = 31080 Conflicting Daily Volume = 101580 N/A (Information Not Available) Accident Rate = 1.703 Accident Rate = 0.123 Accident Rate = 1.376
Hazard Index = 6.217 Hazard Index = 0.450 Hazard Index = 5.021
v/c Ratio for Left Turns = 0.94 v/c Ratio for Left Turns = 0.95 Maximum v/c Ratio = 1.26
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 6.0 0.8 2.6 1.4 5.6 0.6 0.6 1.8 0.8 2.2 1.2 0.6 1.6 2.6 2 4.4 1.2 1.8 0.2 5.0 1.0 1.0 0.6 0.8 1.0 1.6 0.6 0.8 1.4 3 44.2 8.0 20.0 6.6 9.6 0.0 5.8 14.8 10.4 13.2 10.4 7.4 10.8 15.6 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 54.6 10.0 24.4 8.2 20.2 1.6 7.4 17.2 12.0 16.4 13.2 8.6 13.2 19.6 Intersection: 118 Avenue and 97 Street EDMONTON
Dual Left Turn Location(s): EB Left
Phasing Type Lead/Lag North Perm - South Perm - Phasing Bar from synchro East Prot + Perm Lag West Perm -
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 60 658 572 0 2013 69 2 372 190 662 461 10 Daily Volume = 720 7896 6864 0 24156 828 24 4464 2280 7944 5532 120 Total Volume = 15480 24984 6768 13596 Total Approach Volume = 60828
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume - - 5556 - 5556
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) EB EB Collision Type NB SB (Dual) WB Total Collision Type NB SB (Dual) WB Total 1 5 22 23 3 53 1 8 23 25 3 59 2 0 0 0 0 0 2 4 4 6 8 22 3 0 3 3 0 6 3 11 38 15 4 68 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 5 25 26 3 59 Total (over 5 years) 23 65 46 15 149 Total (per year) 1 5 5.2 0.6 11.8 Total (per year) 4.6 13 9.2 3 29.8
EB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 5.2 Annual Accidents = 29.8 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 5556 Conflicting Daily Volume = 60828 N/A (Information Not Available) Accident Rate = 2.564 Accident Rate = 1.342
Hazard Index = 9.359 Hazard Index = 4.899
v/c Ratio for Left Turns = 0.79 Maximum v/c Ratio = 1.03
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 11.8 1.6 4.2 1.4 7.0 0.8 0.8 5.0 1.4 5.8 3.2 1.2 4.8 2.4 2 4.6 1.0 1.4 0.4 4.0 0.2 0.6 2.0 1.0 1.4 1.0 1.0 0.6 2.0 3 14.8 2.2 6.0 2.4 4.2 0.4 1.0 6.2 3.6 3.6 4.0 3.2 4.0 3.6 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 31.2 4.8 11.6 4.2 15.2 1.4 2.4 13.2 6.0 10.8 8.2 5.4 9.4 8.0 Intersection: 137 Avenue and 127 Street EDMONTON
Dual Left Turn Location(s): EB Left, WB Left
Phasing Type Lead/Lag North Prot + Perm Lead South Prot + Perm Lead Phasing Bar from synchro East Prot + Perm Lead West Prot + Perm Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 132 526 327 222 1118 230 184 714 184 662 1245 91 Daily Volume = 1584 6312 3924 2664 13416 2760 2208 8568 2208 7944 14940 1092 Total Volume = 11820 18840 12984 23976 Total Approach Volume = 67620
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume - - 17148 16512 33660
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) EB WB EB WB Collision Type NB SB (Dual) (Dual) Total Collision Type NB SB (Dual) (Dual) Total 1 0 2 18 13 33 1 2 2 24 16 44 2 0 0 0 0 0 2 5 3 1 5 14 3 4 3 0 2 9 3 28 23 16 20 87 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 4 5 18 15 42 Total (over 5 years) 35 28 41 41 145 Total (per year) 0.8 1 3.6 3 8.4 Total (per year) 7 5.6 8.2 8.2 29
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 3.6 Annual Accidents = 3.0 Annual Accidents = 29.0 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 17148 Conflicting Daily Volume = 16512 Conflicting Daily Volume = 67620 N/A (Information Not Available) Accident Rate = 0.575 Accident Rate = 0.498 Accident Rate = 1.175
Hazard Index = 2.099 Hazard Index = 1.817 Hazard Index = 4.289
v/c Ratio for Left Turns = 0.99 v/c Ratio for Left Turns = 0.55 Maximum v/c Ratio = 0.99
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 8.8 1.2 3.2 1.6 5.0 0.6 0.4 2.0 3.2 2.6 3.0 0.4 3.2 2.2 2 3.0 0.6 1.2 0.4 2.6 0.0 0.2 1.8 0.6 0.4 1.2 0.2 1.0 0.6 3 19.0 1.6 8.4 4.6 4.4 0.0 1.6 8.4 5.0 4.0 5.8 3.4 3.8 6.0 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 30.8 3.4 12.8 6.6 12.0 0.6 2.2 12.2 8.8 7.0 10.0 4.0 8.0 8.8 `
Intersection: 137 Avenue and 97 Street EDMONTON
Dual Left Turn Location(s): NB Left, EB Left, WB Left
Phasing Type Lead/Lag North Prot + Perm Lead South Prot + Perm Lead Phasing Bar from synchro East Prot + Perm Lead West Prot + Perm Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction North Approach South Approach East Approach West Approach Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 142 770 210 301 2015 271 270 673 215 357 939 167 Daily Volume = 1704 9240 2520 3612 24180 3252 3240 8076 2580 4284 11268 2004 Total Volume = 13464 31044 13896 17556 Total Approach Volume = 75960
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume 25884 - 14508 12360 52752
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) NB EB WB NB EB WB Collision Type (Dual) SB (Dual) (Dual) Total Collision Type (Dual) SB (Dual) (Dual) Total 1 23 24 12 20 79 1 27 26 14 22 89 2 1 0 1 2 4 2 11 8 5 9 33 3 5 4 2 5 16 3 70 62 38 32 202 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 29 28 15 27 99 Total (over 5 years) 108 96 57 63 324 Total (per year) 5.8 5.6 3 5.4 19.8 Total (per year) 21.6 19.2 11.4 12.6 64.8
NB Dual Left Turn Accident Rate (per million vehicles entry) EB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 19.8 Annual Accidents = 3.0 Annual Accidents = 64.8 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 25884 Conflicting Daily Volume = 14508 Conflicting Daily Volume = 75960 N/A (Information Not Available) Accident Rate = 2.096 Accident Rate = 0.567 Accident Rate = 2.337
Hazard Index = 7.650 Hazard Index = 2.068 Hazard Index = 8.531
v/c Ratio for Left Turns = 0.53 v/c Ratio for Left Turns = 0.85 Maximum v/c Ratio = 1.04
WB Dual Left Turn Accident Rate (per million vehicles entry) Annual Accidents = 5.4 Conflicting Daily Volume = 12360 Accident Rate = 1.197
Hazard Index = 4.369
v/c Ratio for Left Turns = 0.84
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 17.8 2.4 8.2 2.6 9.8 1.6 1.6 4.8 3.6 6.2 5.2 1.8 3.4 7.4 2 6.6 1.6 2.4 1.6 5.8 0.2 0.6 2.0 1.4 2.8 1.8 1.2 1.6 2.0 3 43.6 5.0 19.6 7.2 11.8 0.4 2.4 14.4 13.2 13.2 12.4 5.0 12.0 14.2 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 68.0 9.0 30.2 11.4 27.4 2.2 4.6 21.2 18.2 22.2 19.4 8.0 17.0 23.6 Intersection: 87 Avenue and 178 Street EDMONTON
Dual Left Turn Location(s): WB Left
Phasing Type Lead/Lag North Prot + Perm Lead South Prot + Perm Lead Phasing Bar from synchro East Permitted - West Prot + Perm Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 162 1230 247 172 1032 173 274 350 211 122 272 92 Daily Volume = 1944 14760 2964 2064 12384 2076 3288 4200 2532 1464 3264 1104 Total Volume = 19668 16524 10020 5832 Total Approach Volume = 52044
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume - - - 5664 5664
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) WB WB Collision Type NB SB EB (Dual) Total Collision Type NB SB EB (Dual) Total 1 3 8 7 11 29 1 6 9 10 13 38 2 0 0 0 0 0 2 2 5 4 21 32 3 1 0 2 4 7 3 39 16 10 26 91 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 4 8 9 15 36 Total (over 5 years) 47 30 24 60 161 Total (per year) 0.8 1.6 1.8 3 7.2 Total (per year) 9.4 6 4.8 12 32.2
WB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 3.0 Annual Accidents = 32.2 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 5664 Conflicting Daily Volume = 52044 N/A (Information Not Available) Accident Rate = 1.451 Accident Rate = 1.695
Hazard Index = 5.297 Hazard Index = 6.187
v/c Ratio for Left Turns = 0.46 Maximum v/c Ratio = 0.93
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 7.6 1.2 3.0 0.4 6.2 1.0 0.6 0.8 1.8 3.4 3.0 1.0 2.2 1.4 2 6.6 1.4 3.2 0.4 5.0 0.0 0.2 2.0 1.0 3.4 2.8 1.4 0.8 1.6 3 19.0 2.0 7.8 3.2 6.0 0.4 1.2 8.0 3.4 6.0 6.2 2.2 3.8 6.8 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 33.2 4.6 14.0 4.0 17.2 1.4 2.0 10.8 6.2 12.8 12.0 4.6 6.8 9.8 Intersection: Argyll Road and 75 Street EDMONTON
Dual Left Turn Location(s): EB Left, WB Left
Phasing Type Lead/Lag North Permitted - South Permitted - Phasing Bar from synchro East Prot + Perm Lead West Prot + Perm Lead
Total Dual Left Turn Conflicting Traffic Movements PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 35 1097 211 52 1148 466 384 499 34 579 931 224 Daily Volume = 420 13164 2532 624 13776 5592 4608 5988 408 6948 11172 2688 Total Volume = 16116 19992 11004 20808 Total Approach Volume = 67920
Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume - - 15780 12936 28716
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) EB WB EB WB Collision Type NB SB (Dual) (Dual) Total Collision Type NB SB (Dual) (Dual) Total 1 6 5 14 16 41 1 6 5 14 16 41 2 2 0 0 1 3 2 7 3 2 3 15 3 0 2 2 2 6 3 54 71 15 5 145 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 8 7 16 19 50 Total (over 5 years) 67 79 31 24 201 Total (per year) 1.6 1.4 3.2 3.8 10 Total (per year) 13.4 15.8 6.2 4.8 40.2
EB Dual Left Turn Accident Rate (per million vehicles entry) WB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 3.2 Annual Accidents = 3.8 Annual Accidents = 40.2 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 15780 Conflicting Daily Volume = 12936 Conflicting Daily Volume = 67920 N/A (Information Not Available) Accident Rate = 0.556 Accident Rate = 0.805 Accident Rate = 1.622
Hazard Index = 2.028 Hazard Index = 2.938 Hazard Index = 5.919
v/c Ratio for Left Turns = 0.75 v/c Ratio for Left Turns = 0.84 Maximum v/c Ratio = 0.92
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 8.2 1.0 3.6 1.0 4.2 0.6 0.4 2.8 1.4 3.0 2.0 1.4 2.0 2.8 2 3.2 0.4 1.8 0.8 1.8 0.0 0.4 0.4 0.8 1.6 1.2 0.4 0.8 0.8 3 34.4 6.6 15.6 6.2 6.0 1.2 5.0 10.0 10.6 7.6 8.4 7.2 8.4 10.4 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 45.8 8.0 21.0 8.0 12.0 1.8 5.8 13.2 12.8 12.2 11.6 9.0 11.2 14.0 Intersection: Kingsway Avenue and 109 Street EDMONTON
Dual Left Turn Location(s): NB Left
Phasing Type Lead/Lag North Prot + Perm Lead South Permitted - Phasing Bar from synchro East Permitted - West Permitted -
Total Dual Left Turn Conflicting Traffic Movements PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 47 786 84 716 908 31 0 799 53 93 557 308 Daily Volume = 564 9432 1008 8592 10896 372 0 9588 636 1116 6684 3696 Total Volume = 11004 19860 10224 11496 Total Approach Volume = 52584
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume 11460 - 6684 - 18144
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) NB NB Collision Type (Dual) SB EB WB Total Collision Type (Dual) SB EB WB Total 1 16 11 3 2 32 1 24 12 3 2 41 2 0 0 0 0 0 2 7 5 5 1 18 3 1 1 1 0 3 3 12 8 10 2 32 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 17 12 4 2 35 Total (over 5 years) 43 25 18 5 91 Total (per year) 3.4 2.4 0.8 0.4 7 Total (per year) 8.6 5 3.6 1 18.2
NB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 3.4 Annual Accidents = 18.2 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 11460 Conflicting Daily Volume = 52584 N/A (Information Not Available) Accident Rate = 0.813 Accident Rate = 0.948
Hazard Index = 2.967 Hazard Index = 3.461
v/c Ratio for Left Turns = 0.94 Maximum v/c Ratio = 1.16
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 8.2 1.6 4.2 1.2 1.6 0.2 0.2 4.0 2.2 1.6 1.8 1.6 2.6 2.2 2 3.8 0.2 2.8 0.2 0.4 0.4 0.2 1.0 1.0 1.2 1.4 0.0 0.8 1.6 3 8.2 2.0 4.2 1.4 0.6 0.4 0.4 3.4 2.2 1.8 3.4 1.2 1.6 2.0 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 20.2 3.8 11.2 2.8 2.6 1.0 0.8 8.4 5.4 4.6 6.6 2.8 5.0 5.8 Intersection: University Avenue and 114 Street EDMONTON
Dual Left Turn Location(s): NB Left
Phasing Type Lead/Lag North Prot + Perm Lead South Pemitted - Phasing Bar from synchro East Pemitted - West Prot + Perm Lead
Daily Volume PM Peak to 24 hr Factor = 12 Direction Southbound Northbound Westbound Eastbound Movement Left Through Right Left Through Right Left Through Right Left Through Right PM Peak Hour Volume = 0 1044 34 850 475 247 379 346 26 24 438 1034 Daily Volume = 0 12528 408 10200 5700 2964 4548 4152 312 288 5256 12408 Total Volume = 12936 18864 9012 17952 Total Approach Volume = 58764
Total Dual Left Turn Conflicting Traffic Movements SB Left NB Left WB Left EB Left Total Conflicting Only if dual left turn NB Thru SB Thru EB Thru WB Thru Daily Volume Intersection Configuration Left Conflicting Volume 5700 - - - 5700
Left Turn Collisions Total Collisions Direction of vehicle making left turn (Total over 5 years) Direction of vehicle (Total over 5 years) NB NB Collision Type (Dual) SB EB WB Total Collision Type (Dual) SB EB WB Total 1 28 4 2 12 46 1 38 7 4 14 63 2 1 0 1 1 3 2 2 4 1 6 13 3 3 0 0 6 9 3 24 11 48 21 104 4 N/A N/A N/A N/A 0 4 N/A N/A N/A N/A 0 Total (over 5 years) 32 4 3 19 58 Total (over 5 years) 64 22 53 41 180 Total (per year) 6.4 0.8 0.6 3.8 11.6 Total (per year) 12.8 4.4 10.6 8.2 36
NB Dual Left Turn Accident Rate (per million vehicles entry) Total Accident Rate (per million vehicles entry) General Comments: Annual Accidents = 6.4 Annual Accidents = 36.0 Annual accidents averaged for years 1998 to 2002 inclusive Conflicting Daily Volume = 5700 Conflicting Daily Volume = 58764 N/A (Information Not Available) Accident Rate = 3.076 Accident Rate = 1.678
Hazard Index = 11.228 Hazard Index = 6.126
v/c Ratio for Left Turns = 1.23 Maximum v/c Ratio = 2.19
Annual Accidents Vehicle Day Time of Day Season May-Jun. Collision Type PC M T, W, Th F S, Su 12mid-6am 6am-9am 9am-3pm 3pm-6pm 6pm-12mid Dec.-Feb. Mar.-Apr. Jul.-Sep. Oct.-Nov. 1 12.6 1.6 5.6 2.0 6.4 0.4 1.0 4.2 1.6 5.6 2.8 2.6 3.2 4.4 2 3.2 0.4 1.6 0.2 3.4 0.0 0.0 1.2 0.8 1.2 1.0 0.6 1.0 0.6 3 23.0 3.2 12.2 2.8 4.8 0.0 0.6 10.4 7.2 4.8 7.2 4.6 5.2 6.0 4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Total 38.8 5.2 19.4 5.0 14.6 0.4 1.6 15.8 9.6 11.6 11.0 7.8 9.4 11.0
Appendix D
Hazard Index Ratio Calculations
Total ConflictingThruVolume Total DualLeftVolume No. ofDualLeftPhases Total ConflictingThruVolume Total DualLeftVolume No. ofDualLeftPhases Total ConflictingThruVolume Total DualLeftVolume No. ofDualLeftPhases Edmonton Data-Protected+Permitted Edmonton Data-Protected+Prohibited Calgary Data-Protected+Prohibited Collision Collision Collision Collison Collison Collison Severity Severity Severity No. of No. of No. of Type Type Type Injury Injury Injury Fatal Fatal Fatal PDO PDO PDO HAZARD INDEXCALCULATIONS 3 2 1 4 3 2 1 3 2 1 3512 17167 3602 1135 3538 1850 1689 1615 1896 1842 3723 7 9928 7 40768011862 850 786 1430 272 2382 1959 372 2434 1377 N/A N/A N/A / / / / / / / / / 0 0 N/A 0 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 723 7026 1383 421 1442 362 675 1266 608 869 0 6 6 4 2 7 6 1 5 6503 850 716 963 274 928 846 662 762 502 10 146321244134638 23315511301628205 1 1 72 3 6 4 18 12 12 10 6 4 010122028 000000000 220323201422862101536012202007 02021051323 0000 9 400040101 2 2432242423 2112312111423 Avenue & 23 Avenue & 14 Street SW Calgary Trail Calgary Trail & Anderson Rd Yellowhead Trail Glenmore Trail & & 127 Street Barlow Trail SW 118 Avenue Crowchild Trail & & 97 Street Nosehill Drive NW 137 Avenue & Shaganappi Trail 97 Avenue & Northland Drive 137 Avenue & Barlow Trail & 97 Street 32 Avenu NE 87 Avenue & 36 Street & 178 Street Memorial Drive SE Agryll Road 17 Avenue & 109 Street & Sarcee Trail Kingsway Avenue Barlow Trail & & 75 Street McKnight Blvd NE
University Avenue TOTAL & 114 Street
TOTAL T T N T T N P P o o o o o o r r t t t t o o . . a a a a
o o t t l l l l
e e f f C D C D
c c D D o u o u t t u u n a n a e e a a l l f f d d
l l l l C C L L i i
c c L L
e e N N o o + + T T t t e e f f i i l l o o
t t y y n n l l f f P P
i i t t . . p p V V s s g g
P P o o e r i i e e o o
o o T T o f f h h r l l
n n u u h h m a a h
m m r r s s i u u i b e e e e t
s s V t V i t e o o e d l l d u u m m e e 3 2 1 3 2 1 1 1 6 7 2 1 7 4 1 3 2 2 5 0 9 0 7 8 1 6 4 6 3 3 0 2 5 6 6 3 EDMONTON 6 CALGARY 2 7 4 3 9 1 7 1 1 5 . . 1 3 2 2 2 8 . 0 1 0 3 0 0
Collisions Per Year 2 EDMONTON 0 2 0 2 0 8 1 0 7 . 1 . 3 . . . 6 7 5 0 2 6 Collisions Per Total/ 4 6 7 2 4 3 7 7 4 8 9 5 Phase Per Year 9 Collisions Per Year 1 0 2 0 0 0 2 . . . . . 5 8 1 5 3 . Collisions Per 5 6 0 0 5 Hazard Index 3 0 Phase Per Year 4 0 2 . . . 9 8 9 3 9 1 Hazard Index COST ANALYSIS Prot + Prot + Proh Perm T-Bone HI 2.91 12.50 increase 4.298135 Right Angle 0.89 0.55 decrease 1.624027 Rear End HI 4.93 2.80 decrease 1.755956
Cost Formula Per Phase Changed from Protected + Prohibited to Protected + Permitted 4.298(cost of T - bone) - 1.624(cost of Right Angle) - 1.756(cost of rear end)
Cost Calculator Cost of T-Bone 12000 Cost of Fatal 1400000 Cost of Right Angle 4000 Cost of Rear End 2000 No. of changed Phases 1 Cost 643308.5 * assuming that 10% of the T-bone accidents created will be fatal
BENEFIT ANALYSIS
PM Peak Savings to Daily Savings Days to Years HOUR Weekday 250 AM1 0.6 y Saturday 40 AM2 0.6 y Sunday 30 N1 0.5 y 320 N2 0.5 y PM1 1 y Yearly savings 1920 y PM2 1 y OTHER 18 0.1 y y = savings per vehicle in PM peak hour TOTAL 6 y
Benefit Formula Per Phase Changed from Protected + Prohibited to Protected + Permitted (Total PM peak volume)x1920x(Savings per vehhicle in PM peak)x(1hour/3600 seconds) = savings in hours per year
Benefit Calculator PM Peak Volume PM peak Savings (sec) Savings (hr)/Year 0 Cost of Time/Hour Benefit 0