Conference Interactive Program
To view the 2013 Annual Meeting Interactive Program
TRB 91st Annual Meeting (January 22-26, 2012)
Highway Safety Performance
Jan 24 2012 7:30PM- 9:30PM
Marriott, Salon 2
Effects of State-Specific Safety Performance Functions, AADT Estimations, and Overdispersion Parameters on Crash Predictions Using SafetyAnalyst (12-4332)
SafetyAnalyst performs network screening using empirical Bayes approach which requires safety performance functions (SPFs) in addition to roadway characteristics, traffic, and crash data. Simple SPFs (i.e. crashes are predicted as a function of traffic alone) are used by SafetyAnalyst. These simple SPFs were generated using CA, MN, NC, OH, and WA data. Within the software, these national default SPFs are calibrated to represent the agency’s data. How well these calibrated default SPFs fit another state’s data is a question yet to be answered. This research aims at comparing the fit of Georgia specific SPFs and the national default SPFs calibrated to Georgia data. As hypothesized, it was found that state specific SPFs fit the data well, however, the accuracy of traffic data significantly affected the fit of SPFs. SPFs developed using longer segments and with actual traffic data have lower overdispersion parameter with minimal amount of unaccountable dispersion than the SPFs developed using segments with both actual and estimated traffic data.
Alluri, Priyanka , Florida International University
Ogle, Jennifer Harper, Clemson University
Transportation Research Board. 500 Fifth St. NW, Washington, D.C. 20001
Copyright © 2012. National Academy of Sciences. All Rights Reserved.