Campus Units

Civil, Construction and Environmental Engineering, Institute for Transportation

Document Type

Conference Proceeding


Transportation Research Board 96th Annual Meeting

Publication Version

Submitted Manuscript

Publication Date


Journal or Book Title

TRB 96th Annual Meeting Compendium of Papers

First Page


Conference Date

January 8-12, 2017


Washington DC


To improve the safety of people walking at particular signalized intersections, traffic signal engineers may implement leading pedestrian intervals (LPI) to provide pedestrians with a walk signal for a few seconds prior to the parallel vehicular green indication. Previous research using before-after studies and simple economic analyses shows that LIPs are low cost tools that can reduce vehicle-pedestrian conflicts and crashes at some signalized intersections. Despite this evidence, there is a little guidance for municipalities on when to implement LPIs. this paper develops a marginal costs and benefits framework using quantitative metrics, extending the concept of traffic conflicts and marginal safety-delay tradeoffs to analyze the appropriateness of implementing an LPI at specific signalized intersections. The guidance provided by this method helps quantify the probability of a conflict happening, and provides direction on whether or not to implement an LPI at a given location based upon macroscopic level inputs, including turning movement counts, crash data, and geometry. A case study with sample data indicates that an LIP is cost effective for the scenario presented.


This paper was peer-reviewed by TRB and presented at the 96th Annual Meeting of the Transportation Research Board, Washington, D.C. It can be cited as: Sharma, Anuj, Edward Smaglik, Sirisha Kothuri, Oliver Smith, Peter Koonce, and Tingting Huang, "Leading Pedestrian Interval Implementation as a Marginal Costs and Benefits Problem." No. 17-05116. 2017. Posted with permission.

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