Leading pedestrian intervals (LPIs) are a low-cost proven safety countermeasure that increase pedestrian visibility to turning cars. LPIs give pedestrians 3-7 seconds head start to begin their crossing before the parallel green light, allowing them to enter the crosswalk before turning vehicles begin to move. Studies on LPIs are positive; a study in 2018 found a 13% overall reduction in vehicle/pedestrian crashes (at left turns), with individual results scoring much higher, while a 2010 study showed a 60% overall reduction in vehicle/pedestrian crashes.
The FHWA list of Proven Safety Countermeasures gives the following benefits for LPIs:
- Increased visibility of crossing pedestrians.
- Reduced conflicts between pedestrians and vehicles.
- Increased likelihood of motorists yielding to pedestrians.
- Enhanced safety for pedestrians who may be slower to start into the intersection.
But LPIs without APS put blind pedestrians in danger
Visually disabled pedestrians cannot benefit from the additional LPI crossing time if it is only communicated visually.
Blind or visually disabled pedestrians are trained to use the sound of parallel traffic to identify the beginning of the Walk interval. LPI’s delay the beginning of traffic movement, which can place blind pedestrians in front of turning vehicles, leave them without sufficient time to complete their crossing before the Don’t Walk signal, or even lead them to begin crossing after the Walk interval ends.
Leading Pedestrian Interval
1. Leading Pedestrian Interval
The WALK signal begins 3-7 seconds before the parallel green light, allowing pedestrians to establish themselves in the crossing before vehicles start to move. Note the blind pedestrian in this image, not hearing a surge in traffic, is unaware of the WALK and remains on the sidewalk.
Vehicular Green
2. Vehicular Green
Most pedestrians have had 3-7 seconds to proceed. Vehicles begin to move, and the turning truck #1 yields to pedestrians already in the crossing. Truck # 2 sees the blind pedestrian waiting, and believes they are not going to cross. Now the blind pedestrian hears the surge in traffic, and believes the WALK interval has just begun.
Pedestrian Clearance Interval
3. Pedestrian Clearance Interval
The sighted pedestrians complete their crossings. The blind pedestrian begins their crossing, and comes in conflict with truck #2.
APS allows blind pedestrians the benefits of LPIs.
Accessible pedestrian signals (APS) communicate the Walk signal audibly and through a vibrotactile arrow button, removing ambiguity and providing blind and visually disabled pedestrians equal access to the benefits of the LPI.
The ADA and Section 504 of the Rehabilitation Act require public agencies to make their services, programs, and activities accessible to people with disabilities. LPIs, a public service, certainly qualifies. This is reflected in the 11th edition MUTCD, which requires pedestrian signal heads at any crossing with an exclusive pedestrian phase or LPI with all conflicting vehicles stopped (section 4D.02), and supports the use of APS at these crossings (section 4I.06).
This is a simple matter of equal access to a life-saving innovation. We support the widespread use of leading pedestrian intervals, as long as they are paired with APS to provide their benefits to all pedestrians.
