SNIP2 - A tool for developing a strategic safety improvement plan by multiple agencies

Andrew Tarko
Mario Romero
Mingyang Li
Jose Thomaz
Azam Shafiul

This paper presents a method of systematic evaluation of road safety needs – the Safety Needs Identification Package (SNIP) and a concept called SNIP2 – an expansion that can match identified safety needs with safety interventions at the regional and city levels. SNIP and SNIP2 can be used by agencies involved in safety planning and management.

This paper presents the SNIP concept and its implementation for safety planning on Indiana roads. SNIP utilizes GIS road and crash databases to help identify road locations that experience safety problems such as night crashes, right-angle crashes at signalized intersections, etc. It can also be applied to user-related safety needs such as drunken driving, motorcycle crashes, speeding, or young driver safety.

SNIP2 involves two new key components: (1) a catalog of safety improvement programs and (2) a safety improvement program builder that identifies the most cost-effective safety improvement programs to address the safety needs identified with SNIP. The novelty of the proposed approach is in developing the safety improvement plan based on specific needs already identified for various locations, thereby providing a realistic approach to safety planning. The known safety effectiveness of the considered safety improvement programs and their unit costs allow planners to control the level of spending.

To make the optimization problem tractable for large regions with multiple alternative safety interventions, an approximate greedy search is applied to the knapsack problem to optimize recurring annualized benefits and costs. This simplified approach fits well the long-term transportation planning where a long-term “static” solution is sough while providing identification of focus areas more realistic than the current practice of developing strategic safety plans.

The paper presents the details of the catalog of safety improvements preliminarily developed for Indiana and formulation of the optimization program for selecting improvement programs. It discusses the implementation issues and the expected benefits from coordinating the development of the strategic safety plans by state agencies.



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