California Department of Transportation

Project Development Workflow Tasks (PDWT)

Part 3 - Identify Project Need and Project Initiation Document

II. Project Initiation Document

B. Develop Initial Alternatives (150.10) - Develop Concept Alternatives (WBS 150.10.15)

P42. Request Accident History TASAS Table B

Section 20014 of the Vehicle Code requires accident reports made to or by the CHP shall be available for the confidential use of the Department of Motor Vehicles, Caltrans, and local authorities having jurisdiction over highways. Information from individual reports and/or data should be considered as confidential. Statistical accident data reports are not confidential.

Caltrans electronic database of accident history is called “Traffic Accident Surveillance and Analysis System” (TASAS). The data in TASAS comes from the California Highway system called “Statewide Integrated Traffic Records System” (SWITRS).

Engineering documents, such as PID’s or Project Reports, typically contain the latest three-year traffic accident history data that support the project purpose and need and the proposed improvements. The most common report from TASAS needed by project engineers is the “Table B” Selective Accident Rate Calculation report. A sample Table B report may be found in Figure 3-10 of the Traffic Manual. Table B reports for accident data calculations are available for any highway or section of highway, ramps, or intersections for any time period specified. The report shows both actual and average accident rates, total accidents, fatalities, injuries, multi-vehicles, wet, dark, persons killed and injured and the significance.

Table B report data presented within engineering documents must always be obtained from the appropriate District Traffic Investigations Branch. Project engineers may generate Table B reports using the Timeshare (TS1) computer system for their study and investigation purposes only. Inexperienced users of the TASAS system are at risk of generating inaccurate Table B report data, which can lead to incorrect engineering decisions being made.


Traffic Manual, (Chapter 3-Figure 3-10, Sample Table B)


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This page last updated October 20, 2010