Improving Crash Prediction - A More Relevant Exposure Measure than AADT for Highway-Rail Crossing Safety Models

University  University of Nebraska-Lincoln (UNL)
Principal Investigators  Aemal Khattak, Ph.D., Civil Engineering (PI)
PI Contact Information  262D Whittier Research Center
Lincoln, NE 68583-0851
Office (402) 472-8126  
Funding Source(s) and Amounts Provided (by each agency or organization)  UTCRS  (USDOT UTC Program): $72,250
NE Department of Roads: $36,125
Total Project Cost  $108,375
Agency ID or Contract Number  DTRT13-G-UTC59
Start and End Dates October 2016 - June 2018
Brief Description of Research Project  Safety at the junction of highways and rails has been a concern for a long time and highway-rail grade crossing (HRGC) safety models have been around since 1940s. One of the main inputs to these models is the annual average daily traffic (AADT). It is an estimate of vehicular use of roadways and serves as a measure of exposure of motor vehicles to crashes with trains in HRGC safety models. This project considered a conceptually more relevant measure of vehicular exposure to train-involved crashes at HRGCs — the portion of AADT that actually encounters trains at HRGCs, termed as (AADT)TP in this research. This is a more reasonable and better exposure measure because the probability of having train-involved crashes arises only in the presence of trains at HRGCs. However, obtaining (AADT)TP for a large number of HRGCs is difficult in practice. This report presents a simulation-based method to estimate (AADT)TP for a study location including validation of the results with field-observed data. A comparison between the use of AADT and (AADT)TP in several HRGC safety models showed the possibility of reaching different conclusions; arguments for preferring results obtained by using the conceptually more relevant (AADT)TP are given. This report also presents a classification method to classify HRGCs into groups for estimation of (AADT)TP.
Keywords safety, models, rail crossing, AADT
Describe Implementation of Research Outcomes (or why not implemented) Place Any Photos Here See Report.
Impacts/Benefits of Implementation (actual, not anticipated) See Report.
Project Website