Pedestrian Signal Safety - AAA Foundation for Traffic Safety

The case study intersections in Salt Lake City, Utah and Montgomery County, Maryland had existing
PCTs based on a walking speed greater than 4.00 ft./sec. or a WALK time less than 7 sec.
The available green time is the maximum time that can be allotted to the pedestrian signal interval
based on existing signal timings and phasing. The available green represents the green intervals
for the parallel streets. The available green times do not add up to the cycle length because of time
allotted to exclusive phasing for turn movements, concurrent phasing for approaches on the same
street (such as northbound and southbound approaches), and yellow and red intervals.
Table 14 provides an example for understanding similar data provided for each case study
intersection included in the appendices. The “ ˝”
symbol in the table indicates where the total
pedestrian signal time exceeds the available green time.
As shown in Table 14, the southbound approach (north crosswalk) had an available green time of
34 sec. A walking speed of 4.00 ft./sec. yielded a pedestrian interval of 32 sec.; a walking speed of
3.50 ft./sec. yielded a pedestrian interval of 34 sec. Because this is less than or equal to the available
green time, the pedestrian interval for this approach could be serviced adequately during the time
available without taking time from other phases.
Table 14. Pedestrian WALK and clearance time durations for case study intersection in Minneapolis,
Minnesota.
Approach/
crosswalk
Northbound/
south
Southbound/
north
Eastbound/
west
Westbound/
east
Len gth
(ft.)
3.00 ft./sec.
Clearance time (sec.)
3.50 ft./sec. 4.00 ft./sec. 3.00 ft./sec.
Clearance time with 12-sec.
WALK (sec.)
[Total pedestria n time]
3.50 ft./sec. 4.00 ft./sec.
Available
green (sec.)
75 25 21 19 37˝ 33 31 34
78 26 22 20 38˝ 34 32 34
3 18 15 13 30˝ 27 25 28
50 17 14 13 29˝ 26 25 28
A walking speed of 3.00 ft./sec. resulted in a required time for the pedestrian interval that was greater
than the available green time (38 sec. versus 34 sec.). In this case, the available green could be
increased to meet the time required for the pedestrian interval; however, this action could potentially
take time away from other movements served by other phases. Consequently, this may increase
vehicular delay depending upon traffic volumes. The LOS analysis shows that increases in the
available green time would result in greater delay for the major street approaches.
For this case study intersection, the pedestrian interval exceeded the available green time only for the
3.00 ft./sec. scenario in four of the four crosswalks/approaches. If the City of Minneapolis used the
2003 MUTCD recommendation of 7-sec. (minimum) WALK time instead of the policy-based 12-sec.
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