Traffic Calming Device Implementation Guidebook Analysis and Evaluation

WILBUR SMITH ASSOCIATES I ENGINEERS PLANNERS e ECONOMISTS 2990 BRANDYWINE ROAD c SUITE 125 ATLANTA, GA 303413529 * (770) 936-8650 * FAX (770) 936-8656 the device, and similarly, the existing roadway conditions that may limit the device's implementation. We hope this document meets the needs of the City and its residents. Should questions arise regarding specific details of the traffic calming device implementation process, please do not hesitate to call me at (770) 936-8650. -n2 CRA GHANA * ALBANY, NY ANAHEIM, CA * ATLANTA, GA BALTIMORE, MD BANGKOK. THAILAND CARACAS, VENEZUELA * CHARLESTON, SC CHICAGO. IL CLEVELAND, OH COLUMBIA. SC COLUMBUS, OH * FALLS CHIJRCH, VA a HONOLULU, HI * HONG KONG HOUSTON, TX ISUN, NJ KUWAIT KNOXVILLE. TN EXINGTON, !iY LONDON, ENGLAND * MILWAUKEE, WI 0 NEW HAVEN, CT ORLANDO, FL - OVERLAND PARK, KS PHILADELPHIA. PA * PIITSBUSH, PA RALEIGH NC RICHMOND, VA SALT LAKE CITY, UTAH SAN FRANCISCO, CA SAN JOSE, CA TALLAHASSEE, FL * TAMPA, FL * TORONTO, CANADA WASHINGTON. DC EMPLOYEE-OWNED COMPANY Table of Contents Introduction I Data Collection Procedures for the Implementation of Traffic Calming Devices 3 Analysis And Evaluation 5 Priority and Ranking Procedure 8 Traffic Diversion and The Impact Threshold Curve 10 Traffic Calming Device Details Procedural/Administrative/Regulatory Techniques Turn or Entry Prohibitions 12 Neighborhood Speed Watch Program 13 Radar Trailer 14 Physical Techniques Horizontal Deflection Devices NarrowingTreatments Striping Treatments 16 Median Treatments 18 Curb Extension Treatments One-Lane Slow Points 21 Two-Lane Slow Points 22 Curb Bulb-Outs 27 Weaving Treatments Chicanes 30 Serpentine 32 Vertical ~eflection-Devices Rumble Strips 35 Road Humps 39 Speed Tables 45 Raised Intersections 47 Traffic Circles 49 Traffic Diverters Turning Movement Diverters 54 Diagonal Road Closure/Diversion 56 Residential Neighborhood Gateway Treatments 57 Roadway Closures Full Roadway Closure - 59 Partial Roadway Closure ' 61 Open Roadway Closure 62 Table 1: Summary of Traffic Calming Device Characteristics 64 References 65 Introduction Traffic calming is an engineering methodology to physically change the character of streets, improving pedestrian safety and encouraging drivers to obey speed limits. Traffic calming utilizes a variety of physical devices to alter the geometry of the street, along with more traditional traffic engineering techniques to slow traffic. A SUCC~SS~U~traffic calming plan is (generally) not a single device, but rather a series of integrated improvements to slow traffic and, if desired, to direct traffic to more appropriate routes. When concerns regarding traffic speeds, pedestrian safety, and cut-through traffic arise in residential areas, it is often frustrating for both residents of the area and traffic engineers. The .neighborhood often requests a quick fix solution such as enforcement, reduction in posted speed, or the addition of stop signs. This increases the pressure to implement a haphazard solution that may not be in the best interests of the neighborhood, the jurisdiction, or the travelling public. The use of traffic calming devices must be carefully documented so that they are not used inappropriately, or too frequently. Jurisdictions should have in place a four-phased procedure by which traffic calming devices may be requested, evaluated for appropriateness, and implemented: Documentation of the problem and the need for traffic calming devices; The collection of field reconnaissance and traffic study data; Selecting the proper device to correct the problem; and Monitoring the effectiveness of solving the problem once the device(s) are installed. The City of Atlanta Department of Public Works 1 Traffic and Transportation's Neighborhood Traffic Management Program (NTMP), in place since 1985, provides administrative procedures that document and catalogue complaints from residents concerning neighborhood traffic-related problems. This document builds on this process, assisting staff by providing a basis to objectively rank these requests for calming improvements in order of greatest need (here "need" is defined as the magnitude of the impact felt by residents of existing traffic conditions within a given neighborhood). In order to determine the need for traffic calming measures, traffic studies at the affected area must be conducted. Consequently, field data collection procedures, essential for the assessment of traffic conditions within a candidate area, are also detailed. Finally, the handbook describes a full range of traffic calming measures, the advantages and disadvantages of each, design considerations, and the general traffic conditions to which each is best suited. It is the intention of the Atlanta Neighborhood Traffic Management Program to address traffic problems and concerns on local residential streets. While not intended to make streets play areas for children or adults, the NTMP is intended to generally improve safety for pedestrians, bicyclists, and others who travel along or across these streets. Roadways classified as arterial and above are excluded from receiving traffic calming measures, as the primary function of these roads are for the movement of vehicular traffic. Roadways designated as collectors are excluded from the installation of road hump treatments, Generally, any treatments that divert traffic are not to be installed on streets designated as collectors. As well, there are other streets, (depending on their location and individual characteristics), that may not be eligible for the installation of particular types of traffic calming measures (for example, designated bicycle and emergency response routes). Figure 1 depicts the neighborhoods of the City of Atlanta, as well as roads classified as collector and above (shown by functional classification). Planned designated bicycle routes are also shown. City of Atlanta Trafffc Calming Device Implementation Guidebook Rgure I: Neighbwhoods, Roadways -Classified~- as Arterial or Above, including Bike Routes Planned for 1, 5, and 15 years. Roadways Classified Arterial or Above Bike Routes Planned within 1 Year Wke Routes Planned within 5 years Bike Routes Planned within 15 years Atlanta Neighborhoods Data Collection Procedures for the lmplementation of Traffic Calming Devices Before specific traffic calming treatments are chosen for an area or roadway segment, certain data collection procedures must be undertaken to gauge the specific nature of the traffic problem involved. These procedures are divided into two phases: Collecting field reconnaissance information, and The selection and conducting field studies. Engineering Field Reconnaissance Following appropriate contact with Traffic and Transportation, appropriate staff shall conduct a through reconnaissance of the neighborhood affected by the traffic problem(s) reported by the resident(s), and become acquainted with traffic patterns in a general way. Special attention will be given to the specific issues raised by neighborhood residents. Having completed this reconnaissance, specific study area boundaries will be established, and locations for spot speed studies, average daily traffic (ADT) counts, and turning movement counts (as appropriate) will be selected. Specific gateways to the area will be selected for any origin-destination (0-D) studies that may need to be conducted. The field reconnaissance will also produce an inventory of traffic control devices (stop signs, yield signs, turn prohibitions, traffic signal locations, phasings and timings) that influence traffic movements into or through the neighborhood. The inventory should include all streets within the study area, as well as arterial or collectors that may be adjacent to it, serving as gateways to the neighborhood. General attention will be oriented toward driver observation of such traffic regulations as speed limit signs and stop signs, with a special interest directed at resident reported problems of this nature. This reconnaissance will also look for physical obstructions or other conditions that would compromise motorist or pedestrian safety, given the posted speed limit. Field Studies The types of studies undertaken will be determined by: ' Reported complaints by residents, and ' The results of field reconnaissance. The following table lists'traffic studies that will typically be undertaken to respond to the several general classes of traffic problems: Excess Traffic Volume Speeding ' ADT Counts ' Spot Speed Survey ' Turning Movement Counts ' Accident Study ' 0-D Study In some instances, an area's traffic issues may include more than one class of problem; this condition may increase the number and complexity of studies required. For instance, in some areas, it may be necessary to also conduct pedestrian and bicycle counts if they figure predominately into traffic conditions within the area. The following sections describe the studies listed above: City of Atlanta Traffic Calming Device lmplementation Guldebook ADT Counts: These counts will be conducted in accord with Traffic and Transportation procedures. They should be taken for a period of not less than one weekday (24 hours). ADT counts should be taken along all identified problem streets, on neighborhood streets at gateways to the area, and on adjacent or nearby major arterials or collectors (as appropriate). Turning Movement Counts: These manual counts are required when the principal neighborhood traffic problems result from through traffic. They will be conducted at intersections that serve as gateways to the

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