Development of a Procedure for Prioritizing Intersection Improvement Projects Considering Both Safety and Operational Factors

To better utilize the limited budget allocated for intersection improvements, government agencies are hard pressed to develop an annual plan that can clearly prioritize intersection improvement projects. The current method is based solely on intersection safety with a total focus on cost-benefit ratio of the safety analysis. This paper presents a new prioritizing method, Multi-Layer Prioritization (MLP), which considers on safety and operational factors in order to provide more reasonable and accurate master plan for intersection improvement projects. As an enhanced successive subsetting method, MLP will use three successive layers (screening criteria). Applying the first screening criterion (safety benefit/cost ratio) to the entire population of projects, and then ranking the outcome in a descending order, a list of the projects in question will be produced representing the most important project on top and the least important project on the bottom. Then, the total population of projects will be hierarchically clustered or divided based on the distance between the projects on the list. After that, the elements or projects within the clusters will be processed through a second layer or second screening criterion (delay reduction) to produce a list within the cluster showing the most important project on top and the least important project on the bottom. Based also on the distance between the elements on the list within the first group of clusters a second clustering process should be conducted to arrive to a second group of clusters. Finally, the elements or projects within the second group of clusters will be processed through a third screening criterion (existing delay) to produce a list within the second group of clusters which along with the projects located on the list but sit outside the cluster shall represent the final prioritizing list of projects. A case study showed that the new procedure for prioritizing intersection improvement projects can provide more reasonable results than the existing method since both safety and operational factors are considered. The flexibility of altering criteria and the possibility of the ability to implement the MLP method using a computer program are other two advantages of the new prioritizing procedure