The Development and Evaluation of Calibration Factors for the Rural Two-Lane Highway Draft Prototype Chapter

The Highway Safety Manual (HSM) under the direction of the Transportation Research Board Highway Safety Manual Task Force is a new tool that is anticipated for public release in 2007. The compilation of the research work in the HSM will provide users the best available safety research. One draft prototype chapter (DPC) intended for the Highway Safety Manual focuses on Rural Two-Lane Highways. The procedure used in this DPC has three subcomponents used in the final prediction of roadway accidents. These subcomponents include a base equation, eight accident modification factors, and calibration factor. This study evaluated the procedure for the development of calibration factors used in the DPC for horizontal curves located in the state of Texas. The purpose of calibration factors are to adjust the accident predictions developed using Minnesota data to local conditions. Texas horizontal curve calibration factors were developed from 11,000 accidents, which occurred on 54,000 curves covering more than 7,000 miles of rural two-lane highways. Four alternatives were used to developed calibration factors from this dataset for the 25 Texas Department of Transportation districts. The calibration factor that was considered the most accurate was the alternative which used individual curve data rather than calculating averages of geometric data for different average daily traffic bins. The results for the alternatives that used averages of geometric data were, overall, about 11 percent higher than the alternative based on individual curves. The calibration factors across the state of Texas ranged between 0.8 and 1.8 which indicates that one statewide calibration factor is not adequate.

• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Fitzpatrick, Kay
  • Schneider IV, William Henry
• Conference:
  • Transportation Research Board 85th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2006-1-22 to 2006-1-26
• Date: 2006

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Figures; References; Tables;
• Pagination: 20p
• Monograph Title: TRB 85th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

• TRT Terms: Calibration; Crash analysis; Crash risk forecasting; Data collection; Geometric curves; Highway safety; Prototypes; Rural highways
• Geographic Terms: Minnesota; Texas
• Subject Areas: Bridges and other structures; Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01029401
• Record Type: Publication
• Report/Paper Numbers: 06-2752
• Files: TRIS, TRB
• Created Date: Jul 21 2006 2:34PM