Modeling signalized intersections near highway-railroad grade crossings: Sensitivity analyses of key design parameters

Many roadway intersections throughout North America are located near highway-railroad grade crossings (IHRGCs). Numerous safety, operational, and legal challenges are associated with IHRGCs; and these become significantly more complex when traffic signals are present. Because of the complexity of traffic operations at IHRGCs, existing macroscopic analysis approaches are not suitable for in-depth analyses. Consequently, a more detailed methodology for the analysis of intersections with traffic signals located near IHRGCs was developed. The approach is microsimulation based and relies on hardware-in-the-loop architecture to model the traffic signal controller. To demonstrate the methodology, sensitivity analyses of key design parameters were undertaken, and their impacts on safety and delay were analyzed. Specifically, (a) the maximum train speed and the corresponding length of the detector, (b) the effect of the pedestrian volume, and (c) the effect of the addition of an additional upstream train detector were examined in terms of safety and delay at the IHRGC. The methodology was tested with empirical data from a test bed in College Station, Texas. It was found that the manner in which the maximum train speed was calculated could have a statistically significant effect on delay and a detrimental effect on safety. It was also shown that the addition of an additional upstream detector could reduce delay and increase safety.