Crashes at isolated, rural intersections, particularly those involving vehicles traveling perpendicular toeach other, are particularly bad because of high speeds involved. Many transportation agencies areinterested in reducing the number of crashes at these types of intersections. There are many engineeringtreatments to improve the traffic safety at isolated, high-speed signalized intersections. Intuitively, it iscritical to know which safety treatment may be the most effective for a given set of selection criteria for aparticular intersection. Without a well-defined decision methodology it is almost impossible to decidewhich safety countermeasure or a set of countermeasures would the best option. Additionally because ofthe very large number of possible intersection configurations as well as the varying amount, distributionand type of traffic, it would be impossible to develop a set of guidelines that could be used for allsignalized intersections. Therefore, it was undertaken to develop a methodology whereby commoncountermeasures could be modeled and analyzed before being implemented in the field. Because of thedynamic and stochastic nature of the problem it was decided to employ microsimulation tools, such asVISSIM, for analyzing the countermeasures. A calibrated and validated microsimulation model ofsignalized intersection was used to model two common safety countermeasures. The methodology wasdemonstrated on a test site located just outside of Lincoln, Nebraska. The model was calibrated to thedistribution of observed speeds collected at the test site. It was shown that the methodology could be usedfor the preliminary analysis of the safety treatments.
展开▼
