Pedestrian Signal Safety - AAA Foundation for Traffic Safety

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PEDESTRIAN WALKING CHARACTERISTICS
Most transportation agencies calculate pedestrian interval durations for traffic signals based on
pedestrian walking and crossing characteristics, namely pedestrian walking speeds. The current
edition of the Manual on Uniform Traffic Control Devices (MUTCD) provides the following guidance:
The pedestrian clearance time should be sufficient to allow a pedestrian crossing in the crosswalk
who left the curb or shoulder during the WALKING PERSON (symbolizing WALK) signal
indication to travel at a walking speed of 1.2 m (4 ft.) per second, to at least the far side of the
traveled way or to a median of sufficient width for pedestrians to wait. Where pedestrians who
walk slower than 1.2 m (4 ft.) per second, or pedestrians who use wheelchairs, routinely use
the crosswalk, a walking speed of less than 1.2 m (4 ft.) per second should be considered in
determining the pedestrian clearance time.
However, no further guidance or support is provided regarding what speed should be used or how
to define or measure the proportion of slow walkers or wheelchair users, visually impaired or blind
persons, or persons with other disabilities.
Empirical Data on Walking Speeds
In addition to consideration of mean walking speed (MWS), the 15th-percentile speed also is
important. Fifteen percent of pedestrians walk at or slower than this speed. This is analogous to
most 85th-percentile measures commonly used in traffic engineering and highway design—where 85
percent of the observed values fall within the capabilities of all users observed. Kell indicated that the
15th-percentile speed generally is an accepted value to use in timing signals for pedestrians (Manual
of Transportation Engineering Studies 2000).
In Older Pedestrian Characteristics for Use in Highway Design, the authors provided empirical data
on walking speeds for older pedestrians. Field studies were conducted to quantify the walking speed,
start-up time, and stride length of pedestrians of various ages at 16 crosswalks in four urban areas.
Walking speed was measured from when a pedestrian stepped off the curb until the pedestrian
stepped up on the opposite curb. All pedestrians other than older pedestrians were considered
younger pedestrians.
MWS for younger and older pedestrians was 4.95 feet/second (ft./sec.) and 4.11 ft./sec., respectively
(Knoblauch et al. 1995). The 15th-percentile speed was 4.09 ft./sec. and 3.19 ft./sec. for younger and
older pedestrians, respectively. These data also were stratified by city, pedestrian characteristics,
signal and operational characteristics, geometric characteristics, and ambient conditions.
The report also provided MWS and 15th-percentile walking speeds for only those pedestrians who
complied with the signal indication (pedestrians who started their crossing during the WALK indication
at a pedestrian signal–equipped intersection and during a green signal for parallel traffic at all other
intersections). MWS for compliers was 4.79 ft./sec. for younger pedestrians and 3.94 ft./sec. for older
pedestrians. The 15th-percentile speed for compliers was 3.97 ft./sec. for younger pedestrians and
3.08 ft./sec. for older pedestrians.
Bowman and Vecellio measured pedestrian walking speeds at urban and suburban intersections
in Atlanta, Georgia; Phoenix, Arizona; and Los Angeles–Pasadena, California. Pedestrians were
classified into two age groups: pedestrians aged 18 to 60 and pedestrians older than 60. At signalized
intersections, MWS was 4.46 ft./sec. for pedestrians aged 18 to 60 (based on 316 pedestrians)