01029401

Component

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.

01020180

06-2752

English

20p

2006

Transportation Research Board 85th Annual Meeting

CD-ROM

Figures (3) ; References (8) ; Tables (7)

Calibration; Crash analysis; Crash risk forecasting; Curves (Geometry); Data collection; Highway safety; Prototypes; Rural highways

Minnesota; Texas

Bridges and other structures; Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2006 Paper #06-2752

TRIS, TRB

Mar 3 2006 11:07AM