ACRPC Traffic GIS Database

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Attribute Description Information:

  • AADT ~ A key statistical indicator for roadway counts, known as the “Annual Average Daily Traffic”, or AADT, has been developed to represent the average amount of vehicular traffic in both directions of travel, passing on a given point of road, over a 24-hour period, on a typical day of the year. AADT figures for ACRPC Traffic Count Stations were calculated for a 7-day week (including weekend days). The final AADT figure used for public distribution has been multiplied by a seasonal adjustment coefficients outlined in the annually published VTrans “REDBOOK”. The resulting AADT is then rounded according to the specifications in the “AASHTO Guidelines for Traffic Data Programs”, where: Volumes of 0 to 999 Round to the nearest 10, Volumes of 1,000 to 9,999 Round to the nearest 100, and Volumes >= 10,000 Round to the nearest 1,000.

  • 85TH PERCENTILE SPEED ~ The maximum speed at which 85% vehicles are traveling.

  • 10 MPH PACE SPEED ~ 10 mph range in which the majority of cars are traveling.

  • MEAN SPEED ~ Average Speed.

    • Class 1 town highways are the sections of state routes that continue through larger villages or cities and which carry a state highway route number.
    • Class 2 town highways are those town highways selected as the most important highways in each town. As far as practicable they shall be selected with the purposes of securing trunk lines of improved highways from town to town and to places which by their nature have more than normal amount of traffic.
    • The minimum standards for Class 3 highways are a highway negotiable under normal conditions all seasons of the year by a standard manufactured pleasure car. This would include but not be limited to sufficient surface and base, adequate drainage, and sufficient width capable to provide winter maintenance.
    • Class 4 town highways are all other town highways.

    • 0 – Not part of Functional Classification System
    • 1 – Rural Principal Arterial – Interstate
    • 2 – Rural Principal Arterial
    • 4 – Rural Principal Arterial – Other (not other freeway)
    • 6 – Rural Minor Arterial
    • 7 – Rural Major Collector
    • 8 – Rural Minor Collector
    • 9 – Rural Local
    • 11 – Urban Principal Arterial – Interstate
    • 12 – Urban Principal Arterial – Other Freeway
    • 14 – Urban Principal Arterial – Other
    • 16 – Urban Minor Arterial
    • 17 – Urban Collector
    • 19 – Urban Local.
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ACRPC_AADT ~ This geospatial database is a compilation of collected traffic data for Addison County, Vermont roads from 1958 through 2013, retrieved from Automatic Traffic Recorders (ATRs). The point features of this database represent the best known locations where ATRs were set up for traffic data collection. The data items within the database include; AADT (Annual Average Daily Traffic) Volumes on specific road segments, AADTT (Annual Average Daily Truck Traffic), Speed data (85th Percentile Speed, 10 MPH Pace Speed, Mean Speed, & available posted Speed Limit data), Station site location descriptions, Station ID Numbers (ACRPC station ID’s, as well as the standard ID Numbers used by the Vermont Agency of Transportation – for their traffic counting program.).

This data represents the status of traffic occurance on any particular segment of roadway or intersection assigned a “Traffic Count Station”. This data is used for existing conditions for town plans and transportation studies, traffic impact studies and scoping study alternatives, where data collected over time can yield an expected trend of traffic.

This database consists of data retrieved and processed from Automatic Traffic Recorder (ATR) units utilised during ACRPC’s & VTrans’s annual Traffic Count Programs (conducted during non-winter months). It is expected that the database will be updated at least annually until either fixed-roadway transportation systems or digital database technology are rendered obsolete.

AADT_ID: Database Unique Record ID / Traffic Count Station ID Number

ALT_ID: Alternate Traffic Count Station ID Number

TOWN: Town Name Abbreviation

FIPS: (US Census)

CNTYEAR: Year of latest known Count.

MM: Milemaker/Milepoint or Position of Traffic Count.

LOCATION: Site location text description

JURIS: Jurisdiction (Agency) undertaking traffic count – “V” = VTrans.

ALT_RT: Alternate Route Identifier – “THxx” = Town Highway, “VTxx” = State Route, “USxx” = US Route.

POLE: Utility Pole Identifier Number

C1958 … C2014: Annual Average Daily Traffic (AADT), by year. It is a average amount of vehicular traffic in both directions of travel, passing on a given point of road, over a 24-hour period, on a typical day of the year.

NOTES: Special information about the traffic count station location.

T1994 … T2014: Annual Average Daily Truck Traffic (AADTT), by year. This truck traffic includes all trucks for FHWA vehicle classes ‘2 AXLE 6 TIRE’ through ‘GREATER THAN 6 AXLE MULTI’ and the ‘NOT CLASSED’ Vehicles for ACRPC data. VTrans Truck data was obtained from a modified “Automatic Vehicle Classification History” spreadsheet, obtained from the Traffic Research Unit at VTrans.

ZT2002 … ZT2014: 5 Axle Truck AADT, by year.

FUNC_CL: U.S. DOT/FHWA Functional Classification Codes (*see Attribute notes side).

RD_CLASS: Class of Town Highway where the Traffic Count Station exists (*see Attribute notes side).

RAW1994 … RAW2014: Flag indicating if Raw count files are available at

AB_DIR: Indicates the A and B Direction of Travel (i.e. originating from the ATR “A Tube” to the “B Tube”). This should indicate in cardinal directions for vehicle travel (e.g. NB/SB, or WB/EB, etc.). The first direction is always the A-direction (e.g. NB – Northbound, EB – Eastbound, etc.). This is hopefully assuming that the A-Tube is always installed in the right-most port upon the ATR. This gives the planner the potential ability to help determine direction of travel of traffic on the count, post-count.

Z5TH_A2000 … Z5TH_A2014: 85th Percentile Speed captured for the A-Direction.

Z5TH_B2000 … Z5TH_B2014: 85th Percentile Speed captured for the B-Direction.

PACE_A2000 … PACE_A2014: 10mph Pace Speed captured for the A-Direction.

PACE_B2000 … PACE_B2014: 10mph Pace Speed captured for the B-Direction.

ASPD_A2000 … ASPD_A2014: Average/Mean Speed captured for the A-Direction.

ASPD_B2000 … ASPD_B2014: Average/Mean Speed captured for the B-Direction.

Addison County Regional Planning Commission | 14 Seminary Street Middlebury, VT 05753 | 802.388.3141 |

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