Tarko, A. P., Li, M., Romero, M., & Thomaz, J. (2014). A systematic approach to identifying traffic safety needs and intervention programs for Indiana: Volume II—SNIP2 user manual (Joint Transportation Research Program Publication No. FHWA/IN/JTRP-2014/04). West Lafayette, IN: Purdue University. http://dx.doi.org/10.5703/1288284315498
This report presents the results of JTRP Project: “A Systematic Approach of Identifying Safety Intervention Programs for Indiana (SNIP2),” which aimed to develop SNIP2 to support identification of roads that have excessive crashes of the types defined by the user. In addition, this tool is capable of selecting the best combination of high-crash roads and relevant safety interventions that maximizes the safety benefits and keeps the total cost within the budget and other user-defined constraints.
Unlike other studies considering the implementation time of safety projects, the optimization objective of SNIP2 is to identify an optimal combination of countermeasures renewable within a long time horizon. This simplification is accomplished by representing the projects through their annualized costs and benefits. It allows consideration of many projects for large road networks and it makes the SNIP2 suitable for identification of safety focus areas in strategic safety plans. The SNIP optimizer – a heuristic approximation of a large-size mixed integer knapsack problem based on a greedy search was extensively tested and evaluated. It was found producing optimal or near-optimal solutions in a sufficiently short time. Another research result is a comprehensive catalog of countermeasures for Indiana – a list of countermeasure names, road and crash conditions for the countermeasure relevance, corresponding crash modification factors, and countermeasure costs.
The SNIP2 is computer software developed with close collaboration with the INDOT future users. It includes an updated crash and state road database. A user’s manual describes on the necessary details of the software and various aspects of its use. Two example studies are also included in the manual to illustrate its use and to better presents the SNIP2 features.
road safety, road safety management, safety planning, heuristic optimization, computer tool
Joint Transportation Research Program
Indiana Department of Transportation
West Lafayette, Indiana
Date of this Version