________________________________ ________________________________ www.dot.state.ak.us/stwdplng/mapping/trafficmaps/adtcentral.shtml This report is a compilation of traffic data collected, reviewed and analyzed by the Highway Data Section of the Alaska State Department of Transportation & Public Facilities. Report prepared by: Edith Yan Cover Photo: Unalaska Island to Amaknak Island (Dutch Harbor) bridge taken by Stuart Riley _____________________________________________________________________________ ALASKA DEPARTMENT OF TRANSPORTATION AND PUBLIC FACILITIES CENTRAL REGION PLANNING HIGHWAY DATA SECTION CENTRAL REGION TRAFFIC VOLUME REPORT 2008-2009-2010 Jennifer W. Witt, Chief of Planning Highway Data Section Howard Helkenn, Highway Data Manager Joe Gibbons, Project Review & Programs Planner Edith Yan, Traffic Data Analyst Jennifer Hunt, Statistical Technician Stuart Riley, Field Supervisor ______________________________________________________________________________ ANNUAL TRAFFIC VOLUME REPORT TABLE OF CONTENTS Introduction ................................................................................. Part I Road Listing by Route Name ...................................................... Part II Annual Average Daily Traffic (AADT)/ Daily Vehicle Miles of Travel (DVMT) ..................................... Part III Permanent Traffic Recorder (PTR) Summaries .......................... Part IV Vehicle Classification Data ........................................................ Part V Part I Introduction Introduction The Highway Data Section provides data describing the volumes (number of vehicles) and other characteristics of traffic over the state highway system for use by engineers, planners, administrators, and others whose work requires such information. The traffic data program includes the collection of traffic data, data editing, data processing, analysis, report preparation, data distribution, computer traffic modeling, traffic forecasting, equipment installation and maintenance, data file maintenance, and the annual planning of activities. The Central Region contains the largest concentration of population in the State of Alaska, and is the most far-flung of the three Regions. The contiguous highway system runs from the Homer Spit at the end of the Sterling Highway to the Regional boundaries on the Glenn Highway at MP 118 near Eureka, and the Parks Highway at MP 163 at Little Coal Creek. It includes Kodiak Island and the Aleutian Chain, as well as the isolated villages south of the Kuskokwim River, and all points in between. The Annual Traffic Volume Report is a summary of the data collected in the Central Region. The key elements are: Permanent Counts: Traffic volumes, by direction of travel, collected year-round with Permanent Traffic Recorders (PTRs) at a number of permanently established locations. These counts are summarized yearly and used to provide seasonal adjustment factors applicable to coverage counts recorded at all other locations. Coverage Counts: Traffic volumes, sometimes by direction of travel, typically collected for seven days, with a minimum of one weekend and one weekday. These counts are on a cycle of one to three years at selected locations on the state, borough, and municipal road system. Most coverage counts are taken between May and September because the weather related road conditions make counting very difficult during the remainder of the year. Since summer traffic is generally much higher than other times of the year, the counts are adjusted for weekday and seasonal variations using one or more associated permanent traffic recorders (PTRs) to obtain an estimated Annual Average Daily Traffic (AADT). The calculated AADT then represents the traffic on the specific traffic link on which the count was taken. Vehicle Classification Counts: Traffic volume counts that classify all vehicles by type, based on the axle arrangement, number of trailers, and other vehicle characteristics. Class counts are collected for seven days or more. At key permanent locations data is collected throughout the year using permanently installed detectors and counters. Weigh-In-Motion (WIM): Traffic counts which classify all vehicles by the same criteria as the vehicle classification counts, but include the added dimension of axle weights for all commercial size vehicles. The axle weights are not included in this report, but volume and class data from the WIM sites are included. 2008-2010 Traffic Volume Report I - 1 Definitions: Annual Average Daily Traffic (AADT): The estimated number of vehicles traveling over a given road segment during one 24 hour day. In practice, AADT is usually obtained from a sample (coverage count) adjusted for seasonality assuming roads are open year round. Automatic Polling: A method of obtaining data from automatic counters by telephone from a central computer location with automatic dialing equipment. Automatic counters in the field must have microprocessor memory and telephone connection. Automatic Vehicle Classifier (AVC): Traffic counting equipment which automatically counts and classifies vehicles passing over its detectors, providing a record of those volumes by specific time intervals and vehicle classes. Axle-Body Combination: A vehicle description based on the configuration of axles, leading and trailing units, and tractor body. Axle Correction Factor: The proportion by which a volume count based on axles (e.g., from pneumatic tube detectors) is multiplied to obtain an estimate of the number of actual vehicles. The ratio is 1.0 or less, and is derived from vehicle class counts. Collector: A road classification applicable to roads serving a mixture of local access and through traffic, for which the volume, average speed, and trip length of vehicles using the road are usually lower than for principal or minor arterials, but higher than for local roads. Coverage Count: Hourly (sometimes directional) total traffic volumes collected for seven days, with one weekend on cycle of one to three years. Counts are generally done with a portable automatic traffic counter using pneumatic-tubes (hoses) or inductive loops in the road. Locations of counts remain the same from one rotation year to the next. Daily Vehicle Miles of Travel (DVMT): For any given traffic link or combination of links, the sum of miles traveled by all vehicles; usually calculated as the sum of the products of each link length and annual average daily traffic (AADT) for that link. DVMT = Link Length x Link AADT Highway Performance Monitoring System (HPMS): The data reporting system developed by the Federal Highway Administration (FHWA) for standardized road inventory, physical condition, and traffic use monitoring by all states. Interstate Highway: A highway within the principal arterial category that is also designated as part of the Federal Interstate Highway System. Link: A section of a road for which traffic data is reported. Link termini are located so that the traffic volume is roughly constant on a link. 2008-2010 Traffic Volume Report I - 2 Link Volume: The average number of vehicles passing over a traffic link in a 24-hour period of time. This is equivalent to the Annual Average Daily Traffic. Local Road: Any street (regardless of ownership) that is not classified as any higher type of arterial or collector road. Local roads serve mostly local-access movements, at lower speeds and volumes than roads of other classifications. Milepoints: A linear system of measurement giving distances to features along a route as measured from the start of the route. Features may include intersections, mileposts, businesses, bridges, regional boundaries, city limits, and so on. Mileposts: A system of markers installed alongside a road at one mile intervals and numbered to indicate mileage. Due to realignments that either shorten or lengthen a section of road, most mileposts are no longer accurate measurements, but approximations and function more like landmarks. Minor Arterial: A road serving mostly through movements, but with shorter trip lengths and at lower speeds than principal arterials. Monthly Average Daily Traffic (MADT): The estimated average daily traffic volume for a specific month at a given location. Permanent Count: Hourly, directional or non-directional total traffic volumes collected year-round with Permanent Traffic Recorders (PTRs) at established locations. These counts are used to adjust coverage counts for seasonal variations to yield AADTs. Permanent Detector: A vehicle detector that is permanently installed in a roadway, as compared to a portable detector. The most common permanent detector equipment employs an inductive loop that senses a vehicle's presence as a change in the electrical characteristics of the loop. Piezo electric cables are used in conjunction with inductive loops to detect and sometimes weigh vehicle axles to determine a vehicle's type (classification) and sometimes weight. Permanent Traffic Recorder (PTR): Traffic volume counting equipment that automatically counts vehicles passing over detectors, providing a record of those volumes by specific time intervals. Pneumatic-Tube (Hose) Detector/Counter: A vehicle-detection device/counter consisting of a pneumatic rubber tube placed across a roadway, and which detects vehicles by sensing air pressure pulses from the vehicle axles passing over the tube. Portable Counter: An automatic traffic counting machine which is moved from location to location where needed, rather than permanently installed in one location. Principal Arterial: