A methodology for prioritizing improvements in passive highway-rail crossings
The current Texas Priority Index (TPI) prioritizes high volume active crossings; therefore most high volume crossings have already received improvements in terms of active control devices. Further improvement at these active crossings is not a priority because most crashes occur in active crossings for reasons that cannot be eliminated with additional controls. For example, driving around closed gates or because the drivers are inattentive (Sétra, 2008). So the current research is focused on identifying low volume passive crossings that would benefit from improvements through warrants, then prioritizing the warranted crossings with a new Texas Passive Crossing Index (TPCI) developed for this purpose. Warrants are a series of tasks that make the crossing eligible for upgrade but they are not a substitute for engineering judgment The warrants and the TPCI were developed using data from the Texas Railroad Database (TxRAIL) and Federal Railroad Administration (FRA) database. Warrants were developed after examining existing methodologies and considering all the important attributes. In order to avoid the disadvantages of fixed thresholds found in all existing methodologies, a new percentile threshold concept was developed for the warrants. Since the warrants must ensure identification of all passive crossings that potentially benefit from improvements, they identify approximately 30% of all eligible passive crossings (1,115 out of 3,756). Since Texas Department of Transportation (TXDOT) updates only 75 to 100 crossings a year, a new Texas Passive Crossing Index (TPCI) was developed to prioritize the warranted crossings based on Utility Theory. The weighted average method was used for decision making in order to get the overall utility of the crossing. In order to get these weights, a survey questionnaire was given to railroad experts and their responses were normalized using the AHP theory. The TPCI includes 13 important attributes and the cumulative percentiles of all the relevant attributes are used as utility surrogates. Finally, a ranking procedure was developed that sorts crossings by the multiple crashes followed by the number of warrants met and then by TPCI. The developed ranking procedure results are significantly better than the existing priority indices for ranking and selection of passive railroad crossings in Texas. The new method can be easily implemented into a computerized decision support system to provide a more objective procedure for the selection of passive crossings for safety improvements.