RAIL-HIGHWAY CROSSING HAZARD PREDICTION RESEARCH RESULTS

This document presents techniques for constructing and evaluating railroad grade\ncrossing hazard indexes. Hazard indexes are objective formulas for comparing or ranking\ncrossings according to relative hazard or for calculating absolute hazard (conditional\nexpected frequency of grade crossing accidents) on an individual crossing\nbasis. Relative and absolute hazard indexes are constructed and compared in performance\nwith some hazard indexes in general use. The DOT-AAR crossing inventory for\nall public crossings in the United States and the FRA accident data base for 1975 are\nused. Various measures and displays of performance of hazard indexes in predicting\nthe hazard of crossings as functions of their inventory characteristics and as manifest\nin the U.S. accident experience of 1975 are given. The levels of performance\nthat may be expected of various hazard indexes in various situations are given. Relative\nand absolute hazard indexes constructed on this project are exhibited which\noutperform other hazard indexes tested. Means for shaping a relative hazard index\ninto an absolute hazard index are given. An introductory discussion is provided on\nthe use of accident history in hazard indexes. Preliminary estimates are given of\nsome of the parameters involved in that discussion. Theoretical aspects of this\nreport include some discussions of nonlinear regression and nonlinear discriminant\nana􀁾ysis as well as some aspects of empirical Bayesian statistics.\n