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Leading pedestrian intervals – every second counts

People crossing at 3rd and Marion

Leading pedestrian signal (LPI) in action at 3rd and Marion.

Have you ever seen a traffic signal light up the walk sign ahead of a green light for people driving? 

You might think things aren’t working as they should, but this timing is intentional.

At intersections around the city where we’ve seen a history of pedestrian collisions, we’ve been installing a leading pedestrian interval (LPI). 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. More on that in a sec.

Here’s a video of an LPI in action, at 7th and Olive, downtown.

Meh, it’s just a couple seconds. What’s the big deal?

Turns out, a couple seconds can make a big difference for pedestrian safety. Studies from the Federal Highway Administration show a 60% reduction in pedestrian-vehicle collisions at intersections with LPIs – a significant impact for a relatively minor signal tweak.


A time and a place for everyone.

At some intersections, we’re also installing ‘lag times’ (where the pedestrian crossing time ends early and people driving get a few extra seconds). Most of us have been behind the wheel, trying to turn at a busy intersection. We’ve waited for everyone to cross and by the time everyone gets through, the light is red and we have to wait for another cycle. Lag time gives people driving a chance to get through and clear out an intersection. You can see this at the tail end of the video above.

In both instances, it’s about preventing conflict, giving people (walking or driving) a predictable time and place to get across and through intersections. Using a combination of small changes, we can improve safety and keep people and goods moving.


Here’s your part in making our streets safer for all.

As you’re traveling Seattle’s streets, recognize that every intersection is unique, so stay alert. Even if you have the walk signal, look both ways and watch for turning vehicles. If you’re driving, especially in these darker fall/almost winter days, be extra mindful, slow down, follow the signals and watch for people walking and biking.

With your help, and with changes big and small, we can get closer to our Vision Zero goal of ending traffic deaths and serious injuries on city streets by 2030.