4.4 Pedestrian Timing, ADA Requirements, and Accessible Pedestrian Signals

4.4 Pedestrian Timing, ADA Requirements, and Accessible Pedestrian Signals

A vehicle timing complaint produces a phone call. A pedestrian timing deficiency produces a Department of Justice inquiry. Pedestrian signal requirements sit at the intersection of the MUTCD, the Americans with Disabilities Act, and the U.S. Access Board's public right-of-way accessibility guidelines, and a Level II field technician is the person who physically verifies that the intersection meets them.

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The Three Pedestrian Intervals

A pedestrian phase is built from three parts, displayed in a fixed order.

The calculated pedestrian clearance time must be satisfied by the pedestrian change interval, optionally with help from the buffer interval. The buffer may be used to help satisfy the calculated clearance time, or it may begin after that time has ended — but it is never omitted.

Walking Speed

Pedestrian clearance time is calculated at 3.5 feet per second from the curb or edge of pavement to the far side of the traveled way, or to a median of sufficient width for pedestrians to wait. Where pedestrians who walk slower than 3.5 ft/s, or who use wheelchairs, routinely use the crosswalk, a slower walking speed should be considered.

The Pedestrian Timing Check

The MUTCD adds a separate check that catches crossings where a short walk interval and a fast clearance calculation combine badly: the total of the walk interval and the pedestrian clearance time should be sufficient to allow a pedestrian who left the pedestrian detector (or, where none is provided, a point 6 feet from the curb) to travel at 3.0 feet per second to the far side of the traveled way. The check uses a slower speed and a longer distance than the clearance calculation, and it frequently forces a longer walk interval than 7 seconds at wide crossings.

Countdown Displays

The countdown display shows the number of seconds remaining in the pedestrian change interval and reaches zero at the end of that interval — not at the end of the buffer. The countdown display is optional for pedestrian change intervals of 7 seconds or less and required otherwise. A countdown that runs into the buffer interval, restarts, or displays during Walk is mis-set and must be corrected.

Leading Pedestrian Intervals

A leading pedestrian interval (LPI) starts the Walk indication several seconds before the parallel vehicle green so pedestrians establish presence in the crosswalk before turning vehicles move. Where an LPI is used, the walk interval should still be at least 7 seconds. An LPI has a field consequence a technician must anticipate: the right-turn overlap or permissive right turn must be held red during the LPI, which usually means adding a modifier or omit condition to an overlap.

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Accessible Pedestrian Signals

MUTCD Chapter 4K governs accessible pedestrian signals (APS) and detectors in the 11th Edition. An APS conveys the walk interval non-visually — by audible indication and by vibration — so that a pedestrian who is blind or has low vision receives the same information a sighted pedestrian receives from the WALKING PERSON symbol.

Required Elements

Extended Push Button Press

Holding the button for an extended period (commonly more than one second) may activate additional features: increased crossing time, audible beaconing that alternates sound across the crosswalk to guide a pedestrian along the crossing line, or a speech push button information message naming the street being crossed and the direction of travel.

Where the Push Button Goes

Push button placement is as much a compliance item as timing. The button must be reachable from an accessible route and positioned so that a pedestrian facing the button is facing the crossing it serves. Where two push buttons are mounted on the same pole, they must be separated enough that a pedestrian cannot confuse which crossing each serves — the standard practice is separate poles or a minimum separation with distinct arrow orientations. Where the pedestrian clearance time is sufficient only to reach a median, an additional accessible detector must be provided on the median.

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Field Checks a Technician Performs

1. Confirm the arrow points at the crossing it serves. A vibrotactile arrow rotated 90 degrees on its mount sends a pedestrian who is blind into the wrong crosswalk. This is the most common APS defect found in the field and it is created by careless reinstallation after a knockdown.
2. Verify the locator tone repeats at roughly one second and is short. A continuous tone, a tone that stops entirely, or a tone that keeps sounding while the intersection is in flash are all defects.
3. Confirm the tone responds to ambient sound. Run the intersection during a traffic surge and confirm the volume rises, then confirm it falls in quiet conditions. A locator tone pinned at maximum volume generates noise complaints that lead agencies to disable APS entirely.
4. Press the button and confirm both feedback channels. The button must give a visual, audible, and tactile confirmation that the call was registered.
5. Time the intervals. Stopwatch the Walk, the flashing hand with countdown, and the buffer for every crossing, and compare against the approved timing sheet.
6. Check the countdown zero point. The display must reach zero at the end of the pedestrian change interval.
7. Never disable an APS to silence a complaint. Adjusting volume within the ambient-response range is maintenance; turning the unit off is removing an accessibility feature.