Traffic & Safety

Effectiveness of LPIs in Reducing Pedestrian Crashes at Signalized Intersections on State Highways

Lead Pedestrian Intervals (LPIs) are utilized at signalized intersections to allow pedestrians a three to seven second head-start to enter the crosswalk before turning traffic may proceed. This allows pedestrians to better establish their presence in the intersection, improving their visibility and safety.

 

A study exploring the potential effectiveness of LPIs on New Jersey state highways, and the considerations that should be used to determine where they are warranted, would be useful as the New Jersey Department of Transportation (NJDOT) explores effective measures to improve safety and reduce pedestrian fatalities. Approximately 33% of pedestrian crashes and 21% of pedestrian fatalities that occurred on New Jersey state highways were at signalized intersections. Studies have shown that LPIs are a cost effective strategy to reduce pedestrian conflicts with motorists and improve safety at these locations.

 

-LPIs are a Federal Highway Administration (FHWA) Proven Safety Countermeasure

-FHWA found LPIs reduce pedestrian-vehicle crashes as much as 60% at intersections.

-FHWA's Handbook for Designing Roadways for the Aging Population recommends the use of LPIs at intersections with a high volume of turning vehicles.

-According to FHWA, LPI implementation costs are low, only requiring signal timing adjustments.

-NJDOT's Complete Street's Design Guide (2017) recommends using LPIs at intersections with a high volume of turning vehicles.

-LPIs are included as a signal timing strategy to mitigate conflict between pedestrians and turning traffic in NJDOT's New Jersey Bicycle & Pedestrian Master Plan (2016).

-LPIs are listed as an intersection treatment to improve pedestrian safety in NJDOT's Pedestrian Safety Action Plan Toolbox (2014).

 

Effectiveness

A 2015 study of ten intersections where LPIs were employed in State College, PA found they reduced pedestrian-vehicle crashes by 59%. Pedestrian volumes at intersections studied ranged between 100 and 1,000 crossings per hour. Motor vehicle volumes ranged between 12,000 and 13,500 AADT. LPIs were more effective in study locations with comparatively higher pedestrian volumes and a pre-study pedestrian crash rates. 1

 

A 2000 study of three intersections along four-lane highways in St. Petersburg, FL found that a three-second LPI reduced conflicts between pedestrians and turning vehicles 60%. These locations featured an average of 60 pedestrian crossings per hour. Notably, there was no observed negative impact on these intersections' ability to accommodate motor vehicle traffic over a four month period. 2

 

1. Fayish, Aaron C & Frank Gross. "Safety Effectiveness of Leading Pedestrian Intervals Evaluated by a Before-After Study with Comparison Groups." Transportation Research Record, Journal of the Transportation Research Board 2198 (1), 15-22, Washington, DC.

2. Van Houten, R., Retting, R.A., Farmer, C.M., Van Houten, J., Malenfant, J.E.L. Field evaluation of a leading pedestrian interval signal phase at three urban Intersections. Transportation Research Record. No 1734, 2000, p. 86-91.

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