Traffic signals create gaps in the traffic flow, allowing pedestrians
to cross the street. They should allow adequate crossing time for pedestrians
and an adequate clearance interval based upon a maximum walking speed
of 1.2 m/s (4.0 ft/s). In areas where there is a heavy concentration
of the elderly or children, a lower speed of less than 1.1 m/s (3.5 ft/s)
should be used in determining pedestrian clearance time. Signals are
particularly important at high-use, mid-block crossings on higher speed
roads, multi-lane roads, or at highly congested intersections. National
warrants from the Manual on Uniform Traffic Control Devices are based
on the number of pedestrians and vehicles crossing the intersection,
among other factors.1 However,
judgment must also be used on a case-by-case basis. For example, a requirement
for installing a traffic signal is that there are a certain number of
pedestrians present. If a new facility is being built—a park or recreational
path, for example—there will be a new demand, and the signal could
be installed in conjunction with the new facility based on projected
crossing demand. There may also be latent demand if a destination is
not currently accessible, but could become so with new facilities or redesign.
In downtown areas, signals are often closely spaced, sometimes every block.
Timed sequencing of signals may reduce the amount of time allotted per cycle
for pedestrian crossing to unsafe lengths. Signals are usually spaced farther
apart in suburban or outlying areas, but similar considerations for pedestrian
phasing should be made. When high pedestrian traffic exists during a majority
of the day, fixed-time signals should be used to consistently allow crossing
opportunities. Pedestrian actuation should only be used when pedestrian
crossings are intermittent and should be made accessible to all pedestrians,
including those with disabilities.
| Provide intervals in a traffic system where pedestrians can cross streets
| Where pedestrian traffic is regular and frequent, pedestrian phases should
come up automatically. Pedestrian actuation should only be used when pedestrian
crossings are intermittent.
Signal cycles should be kept short (ideally 90 seconds maximum) to reduce
pedestrian delay. Pedestrians are very sensitive to delays.
Marked crosswalks at signals encourage pedestrians to cross at the signal
and discourage motorists from encroaching into the crossing area.
Adapted from Making Streets That Work, Seattle, 1996