Leading Pedestrian Intervals

Through Vision Zero, we're focused on redesigning Seattle's high injury network of streets - those with a history of serious injury and fatal crashes. We're also taking a proactive approach to systemwide improvements, like lowering speed limits and investing in signal timing changes to increase safety for our most vulnerable travelers - people walking and biking.  

Overview

Failure to yield to pedestrians is one of the leading crash patterns in Seattle. At traffic signals, turning collisions account for 35% of all pedestrian crashes citywide.  

As pedestrians are some of our most vulnerable travelers, we have prioritized pedestrian treatments, especially at traffic signals, to make sure people walking and in wheelchairs are granted the right of way. At intersections around the city, we've been installing a leading pedestrian interval (LPI) treatment to give pedestrians a head start. The LPI works by turning on the walk signal 3-7 seconds prior to people driving getting a green light. LPI's give people walking a head start, which makes the pedestrian more visible, especially for drivers who are turning. The increase in visibility and prioritizing pedestrians in a crosswalk is key to safety, which makes LPIs awesome.

In 2019, we adopted a new policy to evaluate adding a leading pedestrian interval every time we build a new traffic signal or do other signal maintenance work that gives us the opportunity to make this upgrade. We'll make the change unless there's a specific reason why it does not make sense in a particular location. 

Positive Results

Making these smaller changes at a systemwide level adds up. At locations where LPI's have been installed (2009 to 2018), we've seen a 48% reduction in pedestrian turning collisions and a 34% reduction in serious injury and fatal pedestrian collisions. As of November 1, 2020 we have installed almost 300 LPI's, covering 30% of the traffic signals citywide.

More to Come

In 2021 we have an additional 70 LPI locations funded by WSDOT safety grants. In addition, SDOT will continue to implement LPIs when SDOT makes capital improvements to existing signals or when new signals are built.

A graph of LPI installation in Seattle, starting with 2 LPIs in 2010 and growing to 295 by the end of 2020. The fastest growth has been 2018 to 2020.

Leading pedestrian interval map

This map shows existing LPIs (green), LPIs to come (purple), and intersections with all-way walks (blue). Expand the legend panel by pressing the button in the upper left of the map to view more details and turn categories on or off.