Review and Enhancement for Crash Analysis and Prediction: Phase 1-Evaluation of the Crash Studies and Analysis Standard Operating Procedures in Maryland.

摘要

This study offers a comprehensive review of the safety improvement programs adopted by Maryland, FHWA (SafetyAnalyst), and other state agencies, focusing mainly on the following imperative issues: (1) screening and ranking high-crash locations, (2) prioritizing cost-effective projects for safety improvement; and (3) conducting before/after studies for project implementation plans. Based on the resultsof this review, we recommend that the following enhancements be incorporated into the existing safety improvement program in Maryland: (1) develop a multi-criteria method to enhance the current procedures used by the Maryland SHA to select and rank high-crash locations; (2) using SPFs and the observed crash frequency to reliably estimate the site-specific crash frequency: (3) developing and calibrating SPFs for Maryland: (4) using negative binomial distribution to represent the variation of crash frequency; (5) developing and calibrating the crash reduction functions with local data; (6) including secondary costs/benefits in the evaluation; (7) using SPFs of the after period in estimating the do-nothing crash frequency; and (8) Employing nonlinear models for estimating future traffic volume.