Assessing the Effectiveness and Impact of LPIs on Right-Turning Vehicle Behaviors

Abstract: Florida has high pedestrian fatality rates in the U.S., with eight of the country’s 20 deadliest metro areas for pedestrians located within the state. Notably, the Tampa Bay region ranks as the 8th most dangerous metropolitan area for pedestrians (Smart Growth America, 2024). From 2017 to 2020, an average of 707 pedestrians were killed and 7,565 were injured annually on Florida’s public roads. In 2022, the state recorded 10,247 pedestrian-related crashes, representing a 7.09% increase from the previous year (FLHSMV, 2022). Prior research has emphasized that most severe pedestrian-related crashes happen at intersections, and numerous safety challenges surface between right-turning vehicles and pedestrians at signalized intersections.

A leading pedestrian interval (LPI), also known as a pedestrian head start or delayed vehicle green, enables pedestrians to establish their presence on the crosswalk at a signalized intersection generally the first three to seven seconds before right-turning vehicles are given a concurrent green indication. This can be a useful countermeasure for mitigating pedestrian safety issues at signalized intersections. The LPI, one of the Federal Highway Administration’s (FHWA) proven safety countermeasures, is usually recommended for intersections with frequent pedestrian presence and high right-turning vehicle volumes. LPI offers numerous benefits recognized by FHWA: Increased visibility of crossing pedestrians, reduced conflicts between pedestrians and vehicles, increased likelihood of motorists yielding to pedestrians, and enhanced safety for pedestrians who may be slower to start into the intersection.

LPIs have been implemented at over 500 signalized intersections in Florida Department of Transportation (FDOT) District 7, making it the leading district in the state for these installations. This study, sponsored by FDOT District 7, aimed to evaluate the effectiveness of LPIs in enhancing the stopping and yielding behaviors of right-turning vehicles in the district. The research team conducted field studies to collect surrogate data for assessing the stopping and yielding behavior of right-turning vehicles, as well as potential conflicts between those vehicles and pedestrians during the LPI period. Three methods were used to draw conclusions: (1) before-and-after analyses, (2) a cross-sectional study, and (3) an assessment of driver yielding behavior at LPI locations.

The research findings demonstrate the effectiveness of LPIs installed at signalized intersections within FDOT District 7. The percentage of right-turning vehicles waiting and not moving during the first five seconds of “WALK” indication significantly increased by 26% after LPI implementations for the before-and-after study. It was also significantly increased by 18% for the site with LPI compared to the site without LPI for the cross-sectional study. For the study at all eight sites with LPI implementations, approximately 60% of right-turning vehicles waited for pedestrians and did not move. Overall, 91% of right-turning vehicles either waited for pedestrians and did not move or slowed down and yielded to pedestrians to cross a street during the LPI period.