Christopher Daycmday@iastate.edu email >
Research Scientist, CTRE
Peter Savolainenpete@msu.edu email >
About the research
While the effectiveness of active warning devices, such as crossing signals and gates, at railroad crossings is well documented, their presence introduces the risk of errant vehicles striking the devices. To mitigate the impacts of such crashes, guardrail or crash cushions are sometimes installed near crossings.
The main objective of this study was to provide guidance on the design of railroad-highway at-grade crossings, specifically in terms of the location of railroad mast arms/poles and the viability of using guardrails to shield these devices from crashes with errant motor vehicles. Ten years of police-reported crash data for more than 1,800 active crossings in Iowa, along with supplemental data from the Iowa Department of Transportation (DOT) and the Federal Railroad Administration (FRA), were reviewed.
A total of 156 crashes involving signal masts or related hardware occurred from 2007 through 2016 (10 years). Crashes involving signal masts were the most prevalent, followed by vehicles striking the guardrail. Crash rates were higher at crossings with guardrails or barrier, although the differences were not statistically significant. Crash severity was slightly lower when the vehicle struck a guardrail versus a signal mast, but the result was not statistically significant.
Simulation analyses were conducted using the Roadside Safety Analysis Program (RSAP) to compare the benefit-cost ratios of five alternative scenarios. The analyses showed that guardrails appear to provide only a marginal benefit from an economic standpoint; while they tend to reduce crash severity and cost, crashes with railroad signal arms are infrequent, and the small available deflection distance tends to limit their effectiveness. In the optimal scenario, the mast was located 10 feet from the edge of the traveled way without a guardrail. The results also suggest that adding 4 feet of lateral space between the signal support and the edge of the traveled way (from a 6-foot to 10-foot offset) would reduce the probability of a vehicular strike and eliminate the need for a guardrail.