Analysis and methods of improvement of safety at high-speed rural intersections

Since 2006, INDOT has been preparing annually a five-percent report that identifies intersections and segments on Indiana state roads that require attention due to the excessive number and severity of crashes. Many of the identified intersections are two-way, stop-controlled intersections located on high-speed (60 MPH speed limit), divided, multi-lane, rural roads, and any collision that occurs at these intersections could potentially be severe. Design and human factors, as well as other causes, may contribute to the troublesome level of safety at high-speed rural intersections. Some of these factors have been identified while other factors still await identification. A sample of approximately 550 two-way stop-controlled intersections across the state has been selected for analysis. Crash data were collected for a period of four years for these intersections, and the crash data and intersection data were linked together. A trivariate ordered probit model is used to model the factors that increase the frequency and severity of crashes (fatal/incapacitating vs. minor/possible injury vs. property damage only). The crash severity variables depend on each other; the model will estimate how different intersection factors increase the probability of having severe crashes, and also how the different intersection factors increase the probability of having a greater or lower number of crashes. The results of such modeling are presented, which include the factors that increase and decrease the likelihood of crashes. Recommendations for safety countermeasures are made based on these research results