The goal of this research is to understand and quantify the effect of four-quadrant gates on the safety of highway-rail grade crossings. There are several questions including whether four-quad gates reduce the rate of collisions between highway vehicles and trains compared to other grade crossing warning systems and if so by how much. Specifically, the project will investigate and attempt to quantify the marginal benefit of four-quad versus two-quad gate crossings. Related questions include how do crossing characteristics such as Annual Average Daily Traffic (AADT) or daily train traffic volume interact to affect the efficacy of four-quad versus two-quad gates.
This research will use the FRA’s Highway-Rail Grade Crossing Incident Database (Form 57) and the FRA’s Annual Snapshots taken from the Crossing Inventory Database (Form 71). Use of these databases will provide extensive details about the aforementioned characteristics of grade crossings. Using the data from these sources, both serial and parallel comparative methods will be employed. The serial analysis uses negative binomial regression to compare incidents at a population of crossings before and after they were converted from two-quad to four-quad gates. The parallel analysis uses categorical data analysis to compare the incident rate in two populations of crossings in which we control for Annual Average Daily Traffic (AADT) and train frequency but that differ in their use of two-quad versus four-quad gates. Preliminary results
suggest that there is little difference in the incident rate of crossings equipped with four-quad gates compared to those with two-quad gates calling for more in-depth statistical analysis, and an investigation comparing motor vehicle operator behavior at crossings with these two types of warning systems.