Traffic forecasting

Planning-level forecasts | Project-level forecastsGeometric design values | Vehicle classification data

Traffic forecasting is an important component of the Wisconsin Department of Transportation's (WisDOT's) planning, design and operations. It transforms a wide array of traffic, demographic and economic data into information essential to engineers, intercity and urban planners, project programmers and policy makers. Chapter 9 of the Transportation Planning Manual (TPM) contains the WisDOT policies and procedures for traffic forecasting. Refer to Section 1.4 of the TPM for forecast requirements.

A traffic forecast is a data element identifying future roadway traffic volumes. The National Highway System (NHS) designation, jurisdiction of the roadway and the project improvement type help determine if a forecast is required and the type of forecast (planning-level or project-level) necessary.

If you have questions or need additional information on any of the following items, send an email to Spatial files are available for highway data and traffic count locations.

Planning-level forecasts

Planning-level forecasts fulfill requirements for preservation projects on the State Trunk Highway System (including Connecting Highways) that are part of the National Highway System (NHS). They consist of forecasts produced by the Traffic Analysis Forecasting Information System (TAFIS) and previously completed project-level forecasts. TAFIS is an automated program that produces forecasts based on a statistical analysis of a traffic count site’s historical traffic counts. For information about TAFIS, refer to Section 30 of the TPM. The DT1601 - Traffic Forecast Request and delivery process is not part of planning-level forecast production.

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Project-level forecasts

Project-level forecasts are detailed analyses performed for non-preservation projects. They may include a mainline and/or turning movement forecast. Request a project-level forecast using form DT1601 - Traffic Forecast Request. Complete the DT1594 - Forecast Review Request form for a review of project-level forecasts completed by consultants or entities working on WisDOT projects.   

Geometric design values

Geometric design values refer to values calculated using site-specific automatic traffic recorder (ATR) data, or design values based on regressions of statewide ATR data. Refer to Sections 40.1 and 40.3 of the TPM for more information about geometric design values.

Geometric design values consist of automatic traffic recorder data and regression estimates. The file below contains the design hour volumes calculated using data at specific ATR sites. The spreadsheet also contains the regression estimates described below for statewide data.

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Generally for ATR sites the most recent ATR data are used. For non-ATR sites, estimates based on regressions of statewide ATR data are used to calculate the design values.

K-factor regression data

The data in the K-factor regression tables is organized by the Seasonal Factor Group (SFG), number of roadway lanes, and annual average daily traffic (AADT). Refer to Section 40.3 of the TPM for more information regarding the K-factor regression data.

Directional split

The directional split (D) is the proportion of traffic occurring in each direction in the 30th highest traveled hour of the year. The directional splits in the table are organized by the Seasonal Factor Group.

Peak and design hour truck percentages

The peak and design (100th) hour truck percentages are organized by the Seasonal Factor Group. T(PHV) and T(DHV) are calculated by multiplying the percentage in the table for the given seasonal factor group by the total truck percentage for the site.

Vehicle classification data

Vehicle classification data is collected by the Bureau of State Highway Programs’ Data Management Section.

Axle classification counts measure the number and spacing of axles to determine the vehicle type while length classification counts measure the length of the vehicle.

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