Leading Pedestrian Interval

Leading Pedestrian Interval

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A leading pedestrian interval (LPI) is a pedestrian safety measure used at roadway intersections with traffic signals. Intersections with pedestrian and car traffic often experience conflict between these two groups, with potentially dangerous consequences for the pedestrians. The term LPI refers to when the ‘walk’ signal appears three or more seconds before the green traffic signal. The ‘walk’ signal then remains active for the duration of the green signal. This brief timing adjustment allows pedestrians more time to cross the street, and increases their visibility to drivers, especially those making turns [1].

Safety

Leading pedestrian intervals are designed to reduce conflicts between pedestrians and cars. The additional seconds—generally three or four—give pedestrians slightly more time to cross an intersection. Because pedestrians can start across before the cars begin moving, they are already well into the cross walk when the signal changes to green. Drivers are therefore able to see pedestrians more easily than if they were standing on the curb [1].

Although LPI is aimed primarily at aiding pedestrians, it also has benefits for drivers. The length of green signal time for cars is reduced with LPI, but the resulting fewer pedestrian/car conflicts have caused drivers to report an improved level of overall service [1].

LPI is particularly useful for intersections where school children cross the street. Setting up traffic signals with LPIs allows greater visibility and therefore safety for the children, and gives adult crossing guards time to enter the crosswalk and be seen by drivers, before they begin directing children across the street [2].

Installation

Leading pedestrian intervals are relatively simple and inexpensive to set up in intersections that already have traffic signals. A change in the phasing of the lights is made at an average cost of a few hundred dollars, plus a couple hours of work for the installation [1]. Compared to the cost of installing a traffic signal, which can range from $30,000 to $140,000, setting up an LPI is a reasonable modification [2].

Effectiveness

Drivers and pedestrians alike have given positive reports following the installation of LPIs. However, not enough research is available to offer conclusive statistics on their overall effectiveness.

Other Measures

To improve an intersection for pedestrians, there are some other options:
1. No Right Turn on Red – Drivers generally direct their attention toward on-coming traffic when making a right turn during a red signal. This diverts their attention away from the crosswalk to their right. Instituting a No Right Turn on Red law, or setting up certain hours for No Right Turn (during school openings and closings, or other times of heavy pedestrian traffic) can improve safety at an intersection [2].
2. Countdown Timer – A Countdown Timer displays the number of seconds that pedestrians have to cross the street before the light changes. This system can aid pedestrians in choosing whether to start across the intersection, or to cross more quickly in order to avoid the on-coming traffic [2].
3. HAWK (High-Intensity Activated Crosswalk) – HAWK signals were developed for school crossings by the city of Tucson, AZ. An overhead sign tells drivers to 'stop on red' for pedestrians. When pedestrians wish to cross, they push a button, and a traffic signal flashes yellow, then solid yellow, then red to drivers. Pedestrians receive a walk signal. The drivers’ signal then switched to flashing red, indicating that they may proceed when safe. The pedestrians’ signal changes to a countdown 'don’t walk' signal. HAWK has greatly improved pedestrian safety in Tucson [2].

ALSO ON THE LIVABLE STREETS NETWORK

Raised Crosswalk (StreetFilms, 2/12/08)
City Pedestrian Crossings are Discriminatory by Design (StreetsBlog, 12/17/07)
Call for Ped Safety Measures on Third and Fourth Avenues (StreetsBlog, 6/11/07)

REFERENCES

Each source is referred to by the same number every time it is cited. Please keep citation style consistent.

[1] Stygerwal, Ken, Tommy Holland, and Bob Faris. Orlando, FL. "Leading Pedestrian Interval." Walking Info.org: PedSafe. 7 Apr. 2008.
[2] "Traffic Signals." SafeRoutesInfo.org. 7 Apr. 2008.