Pedestrian Problems

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At many intersections and mid-block crossings, full-time pedestrian signals (i.e., those activated every cycle) are not warranted due to the low number of pedestrians using the location.

In those cases, push-buttons are often used to allow crossing pedestrians to activate a signal. Typically, these buttons may be used to do one of the following:

extend the green phase of the signal for traffic crossing in the same direction to allow more time for pedestrians to cross;

extend the WALK phase of the pedestrian signal;

acuate the green traffic signal or pedestrian signal at locations with minimal cross-street traffic or at mid-block locations; and/or

provide a quicker WALK interval to minimize the wait time.

While the intent of these buttons is to enhance pedestrian safety, the installation and maintenance practices associated with the devices often leads to widespread nonuse by pedestrians. In a study by Zegeer et al. (1985), problems found with respect to these devices included:

Location of the push-buttons away from the crosswalk and out of view or out of reach;
Signing for the push-buttons was often nonexistent or confusing in that it was not clear which button was associated with each crosswalk; and
Some buttons were inoperative during part of the day with no message to the pedestrian to indicate this practice.

All of these problems result in a lack of confidence on the part of pedestrians and results in the nonuse of the pedestrian push-buttons.

One alternative or supplement to push-buttons is passive pedestrian detection. Using microwave or infrared sensors mounted overhead, pedestrians waiting to cross can be automatically detected. This information is then relayed to the controller to activate the pedestrian signal.

Push buttons are sometimes located such that approaching pedestrians would have to make a special effort to activate the signal. This inconvenience often leads to nonuse.

Solutions

Microwave Detector

Infrared Detector

Another problem for pedestrians may be the amount of time provided to safely cross the street. The Manual on Uniform Traffic Control Devices assumes a 4 ft/sec walking speed to establish pedestrian signal timings (FHWA, 1988). The Transportation and Engineering Handbook (ITE, 1982) states that speeds of 3.0 to 2.25 ft/sec may be more appropriate to accommodate slower pedestrians.

Numerous research studies have examined walking speeds for pedestrians of all ages and capabilities. As a result of many of these efforts, it is recommended that a design walking speed of 2.8 ft/sec be used to accommodate the shorter stride, slower gait, and longer start-up times of older pedestrians (Staplin et al., 1998)

Selecting the appropriate walking speed to use in establishing pedestrian signal timings can be difficult if the characteristics and resulting speeds of pedestrians at a location are extremely varied, or even worse, are unknown. In many of these cases, the predominate speed of the slower pedestrians may be used to control the signal timings. During cycles when no "slower" pedestrians are present, this approach produces unnecessary delay for motorists. If a faster walking speed is used, the delay to motorist would be minimized, but the slower pedestrians may not have enough time to safely cross the street.

One way to accomodate all pedestrians and minimize motorist delay is through the use of passive pedestrian detection. Using microwave detectors mounted overhead and aimed at the crossing area, slower pedestrians can be detected to extend the clearance interval of the signal and allow them to safely cross the street. At the same time, motorists will not be delayed if pedestrians needing extra time to cross are not present.

REFERENCES:

Zegeer, C.V., Opiela, K.S., and Cynecki, M.J., Pedestrian Signalization Alternatives (Report No. FHWA/RD-83/102), Federal Highway Administration, Washington, DC, July 1985.

Manual On Uniform Traffic Control Devices, Federal Highway Administration, Washington, DC, 1988

Transportation and Traffic Engineering Handbook, Institute of Transportation Engineers, Washington, DC, 1982.

Staplin, L., Lococo, K., and Byington, S., Older Driver Highway Design Handbook (FHWA-RD-97-135), Federal Highway Administration, Washington, DC, January 1998.

Walking speeds typically used to establish pedestrian signal timings may not account for slower pedestrians. As a result, older pedestrians may have difficulty crossing the street within the established time.

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