Pedestrian Safety Guide and Countermeasure Selection System
An example of concurrent signal phasing, where the pedestrian signal phase activates simultaneously with the parallel vehicle phase, permitting motorists to turn left or right across pedestrians’ paths after yielding to pedestrians.
Source: pedbikeimages.com - Dan Burden (2006)
In general, shorter cycle lengths (ideally less than 90 seconds) and longer walk intervals provide better service to pedestrians and encourage better signal compliance. For optimal pedestrian service, fixed-time signal operation usually works best because it provides an automatic pedestrian phase.
Pedestrians usually receive more frequent crossing opportunities and experience less delay with concurrent signal phasing than with exclusive signal phasing, which must service vehicle traffic and pedestrian volumes separately. When pedestrians are required to wait a long time for a pedestrian interval, many will simply choose to ignore the signal and cross during a gap in traffic, negating the potential safety benefits of the exclusive signal. Exclusive pedestrian phases, without accessible pedestrian signal technology, introduce a problem for pedestrians with visual restrictions, as the audible cues associated with parallel traffic streams will lead pedestrians to cross at inappropriate times.
To be useful to pedestrians with vision restrictions, an LPI needs to be accompanied by an audible signal to indicate the WALK interval. There are some situations where an exclusive pedestrian phase may be preferable to an LPI, such as when high-volume turning movements conflict with pedestrians crossing.
Hot response signals may be particularly appropriate at midblock crossing locations where the distance to other signalized crossings is significant. Hot response signals help reduce unnecessary delay for both pedestrians and vehicles at locations where pedestrians will typically use the pushbutton but cross before the pedestrian signal is active.
There are several types of signal phasing for pedestrian signals. Signal phasing options include the following:
Signal Coordination – This measure involves timing the phasing of adjacent traffic signals along a corridor to control the speeds of motor vehicles. For example, the sequence of green signal cycles can be timed to speeds of 20 or 25 mph.
Concurrent Phasing – Pedestrian signal phase activates simultaneously with the parallel vehicle phase, permitting motorists to turn left or right across pedestrians’ paths after yielding to pedestrians.
Exclusive Pedestrian Phasing – Refers to a pedestrian phase that is active only when all conflicting vehicle movements are stopped across an approach to an intersection. When vehicles are stopped on all approaches to an intersection while pedestrians are given a WALK indication, the phasing is referred to as “exclusive” or as a “pedestrian scramble” (see Traffic Signal Enhancements). Intersections with pedestrian scramble phases often feature pedestrian crossing markings indicating pedestrians may walk diagonally across the intersection. Exclusive pedestrian timing has been shown to reduce pedestrian crashes by 50 percent in some downtown locations with heavy pedestrian volumes and low vehicle speeds and volumes.4
Split Phasing – The vehicular green phase is split into two parts: (1) pedestrians receive protected walk time while vehicles travelling parallel are given a green signal to go straight but not turn, and (2) the pedestrian DON’T WALK is activated when vehicles are permitted to turn. A study in New York City suggests the split phasing significantly reduces pedestrian conflicts, crashes, and illegal pedestrian crossings.5
Leading Pedestrian Interval (LPI) - An LPI gives pedestrians an advance walk signal before motorists get a green signal, giving the pedestrian several seconds to start walking in the crosswalk before a concurrent signal is provided to vehicles. This makes pedestrians more visible to motorists and motorists more likely to yield to them. Typical LPI settings provide 3 to 6 seconds of advance walk time. LPI has been used successfully in several places, such as New York City, for two decades and studies have demonstrated LPI reduces conflicts and crashes for pedestrians.6
Hot Response – A hot response detector activates a pedestrian signal immediately upon actuation, subsequent to providing at least the minimum allowable green time for conflicting vehicles. Hot response signal phasing is desirable where pedestrian crossing volumes are significant or high pedestrian compliance is desirable.
Left turn phasing – Use of concurrent, protected/permissive, or protected left turn phasing provides different levels of conflict reduction with parallel pedestrian movements. These variations on left turn signal phasing provide increasing levels of conflict reduction between vehicles and pedestrians using a parallel crossing (see Left Turn Phasing section).
Authors and Acknowledgements