Leading Pedestrian Intervals (LPIs) give sighted pedestrians a head start to cross before traffic moves, improving safety, but only if you can see the pedestrian signal. For blind pedestrians, LPIs without Accessible Pedestrian Signals (APS) create real danger.
I was in a nearby city for a conference earlier this year and staying at a different hotel. On my six-block walk to the conference hotel, I crossed several signalized intersections with Accessible Pedestrian Signals (APS). One in particular just felt off. The APS didn’t seem to be working, but I couldn’t put my finger on what was wrong with the rest of the intersection that first day. To be honest, I didn’t have time to analyze it. I just needed to get to my destination without delay. The second day, I was with a friend who uses a wheelchair. At this intersection, she took off into the crosswalk when my ears were telling me we didn’t have the walk signal. While she’s a certified scuba diver (eek!), I didn’t have her pegged as impulsive and fearless enough to make a run for it at an intersection. I didn’t hear any cars starting to move on the street beside me. In fact, I could hear some cars at various points of the intersection, but no one was moving. Then it hit me. This was an intersection with a Leading Pedestrian Interval (LPI) but the signal was not accessible because there was no audible message describing the walk signal. So here I was using all the training and skills I had been taught and relied on to cross the street safely as a blind pedestrian and still missing the walk interval entirely because there was no APS audible messaging. Fortunately, I was at a traffic engineering conference, and as one of the speakers, I had the attention of exactly the right audience.
LPIs are a traffic intersection strategy designed to give pedestrians a head start, typically 5-7 seconds, before parallel traffic gets a green light. This lets pedestrians enter the crosswalk and become more visible to drivers making left or right turns approaching the crosswalk. This gives the pedestrian time to start crossing and establish themselves in the crosswalk before vehicles start moving. LPIs are especially useful at intersections where there are a high number of conflict points, such as pedestrians and a higher-than-usual volume of turning vehicles. However, for blind pedestrians, LPIs without an APS actually increase the risk of injury or death at these intersections.
Many cities are adopting LPIs as part of their Vision Zero initiatives, adopted to bring the number of traffic injuries and fatalities down to zero, especially among vulnerable road users, such as pedestrians and cyclists. LPIs are a proven safety tool, increasing pedestrian visibility, reducing the potential for conflicts between vehicles and pedestrians or cyclists, and are a low-cost way to align with Vision Zero goals, usually just requiring adjustment to signal timing software. According to the FHWA, LPIs have been shown to reduce pedestrian/vehicle crashes by up to 60% at intersections where they have been used. Cities like New York, San Francisco, and Portland have implemented LPIs city-wide as part of their Vision Zero initiatives to design safer systems. For sighted pedestrians and cyclists, that 5-7 second headstart gives you a good bit of time to get well into the crosswalk before traffic starts up.
Cities are also installing more Accessible Pedestrian Signals (APS), which are designed to make the visual information in an intersection audible for pedestrians who are blind or have low vision, including those who are deaf-blind. This enables us to make decisions about when to cross with as much of the same visual information about the intersection as possible that sighted pedestrians have access to. If it is lined up and adjusted correctly, the APS tells us when to cross (rapid tick, speech message, vibrotactile arrow), the direction of travel on the crosswalk (direction of arrow), street names and other important information (actuated by a button press of at least one second) and tells us when the clearance interval starts (when the APS reverts back to a locator tone).
LPIs that don’t have APS to provide an audible crossing cue actually increase the risk of pedestrian/vehicle conflicts for blind pedestrians. We are taught to listen for the surge of traffic on the street beside us to know when the walk interval has started, and it’s time to begin crossing. In the absence of an LPI, this usually indicates the onset of the walk interval. For LPIs without APS, blind pedestrians will have no idea that the time to start crossing is happening and will continue waiting for a surge in traffic beside us to cue us to start walking. This puts us at risk for turning vehicles and puts us out in the crosswalk when drivers are not expecting us to be there.
Another issue is that too often, cities are installing LPIs wholesale, at both high-risk intersections where they’re needed and at locations where they aren’t, without conducting an engineering study. Because LPIs are viewed as universally beneficial and relatively low-cost, there’s no requirement for a study to justify their use. But that assumption comes at a cost. When cities spend limited funds adding LPIs where they’re not truly needed, they may then lack the resources to install APS at all of those same intersections where APS are now critically needed for accessibility. It’s essential to evaluate whether an intersection has a crash history or turning conflicts that actually would benefit from an LPI. If it does, then APS must be included to ensure all pedestrians, including blind, visually impaired, and deafblind individuals, have equal access to cross safely. By doing the engineering study, limiting, and prioritizing the installation of LPIs, you will have the necessary funds to install APSs and ensure the intersection is accessible for everyone.
I can hear a few comments already, “Why don’t you just cross when you hear all the other people crossing?” That’s a good question. Let me offer a different perspective. Have you watched sighted pedestrians crossing the street? In my city and others I’ve been in, sighted pedestrians are a bit unpredictable and will cross sometimes when there is a gap in traffic (like I thought my friend was doing) rather than wait for a pedestrian phase. So, blind pedestrians are taught not to follow other pedestrians because they can be unpredictable and unreliable. Sometimes people just don’t make good decisions, and I don’t want to be following one of them over the cliff or into the crosswalk. I’d rather just rely on the tools and skills I have at hand. This is one of those instances where my ears alone aren’t enough. Without an audible cue when the pedestrian interval starts, I’m standing and waiting for my audible nearside parallel traffic surge, missing the actual time to cross.
Think about it this way, with an LPI, sighted pedestrians get a 5-7 second head start. The usual walking speed used to configure the pedestrian clearance phase is 3.5 feet per second. If I apply that walking speed to the 5-7 second head start given by an LPI for the pedestrian walk interval, then sighted pedestrians will have a 17.5 to 24.5 feet head start across the crosswalk that blind pedestrians don’t have. That’s enough to get well into the crosswalk or even all the way across a narrow street. Drivers are not expecting someone to start crossing when the light turns green, but that’s exactly what happens if I miss the head start. I’m out in the crosswalk when drivers do not expect me to be there, which increases the risk of pedestrian-vehicle accidents and injury. The audible cue timed with the Leading Pedestrian Interval is critical for safe and expedient crossing by ALL pedestrians, including blind and visually impaired pedestrians.
So, what actionable steps can you take to ensure the safety of ALL pedestrians, including those who are blind, visually impaired, and deafblind?
- Does the intersection have a crash history or significant turning conflicts that indicate a need for an LPI? LPIs should be reserved for locations where they’re truly needed, so limited funds can also cover APS installation at those same locations to ensure accessibility for all pedestrians.
- Does the APS begin its audible walk indication at the start of the LPI phase? Any delay increases the risk for blind pedestrians.
- Is the APS close to the crosswalk it controls? On the outside (farthest from the center of) the intersection? Best placement for blind pedestrians
- Do tactile arrows point in line with the crosswalk in the direction of travel? Not at the crosswalk departure point.
- Are APS volumes automatically adjusted for ambient noise? 5 dB above and heard within a minimum of 6 feet and a maximum of 12 feet.
- Does pressing and holding the button activate additional information? The additional information is helpful for nonvisual navigation.
- Does the installation meet MUTCD and PROWAG standards? These standards are best practice for accessibility and ADA compliance, backed by solid research.
I’d love to hear from planners, engineers, and advocates working on this challenge. How is your community addressing LPIs and APS integration?
📩 Let’s connect—Suzette May, LLC provides conference presentations, guest lectures, and workshops on APS integration and blind pedestrian safety. https://www.linkedin.com/in/suzettemay
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