Using the Rural Two-Lane Highway Draft Prototype Chapter

Abstract

The TRB Highway Safety Manual Task Force is providing direction and oversight in the preparation of a new document to be called the Highway Safety Manual (HSM). The complete version of the HSM is expected to be released to the public in 2007. A draft prototype chapter (DPC) for rural two-lane highways is available for review. A Texas Department of Transportation project explored the use of the DPC by applying the methodology to two case studies and exploring methods to develop calibration factors. The lessons learned from the effort can be used to improve the DPC along with other chapters in development. Additional guidance is needed on (a) how to identify segments, (b) acceptable minimum segment lengths, (c) how best to combine the predictions for intersections with those for tangents and curves, (d) the key variables within the procedures and appropriate assumptions when data for those variables are not available, (e) the confidence in the approach for individual roadway segments as opposed to a roadway, (f) the potential of using confidence intervals in the prediction process, and (g) how best to use the predictions generated from the methodology.