Subproblem 2a  Page 1 of 2 
ID# C502A01 
Subproblem 2a:
Analyzing the Effects
of Pedestrians
Step 1. Setup
Because of the large
number of pedestrians at this intersection, we might want to consider an
exclusive pedestrian phase. We have resolved part of the pedestrian
conflicts with vehicles by closing the northbound approach to vehicular
traffic in
Problem 1. However, the northeast movement of pedestrians from
parking to classes suggests a diagonal crossing might be worth some
consideration.
Assuming we need to
maintain the 120second cycle, we need to compute the pedestrian green time
for the diagonal movement crossing. Using a crossing distance of 50 feet, a
crosswalk width of 10 feet and a 4feetpersecond walk speed, the minimum
pedestrian time is calculated to be about 20 seconds. This assumes 500
pedestrians in thirty 120second cycles per hour, or 17 per interval in the
following formula from HCM Equation 162:
Incorporating this
value into an exclusive pedestrian phase yields the following timing for the
intersection:

Phase1 

Phase2 

Phase3 
G = 73 sec 
G = 17 sec 
G = 20 sec 
Y = 4 sec 
Y = 4 sec 
Y = 0 sec 
R = 1 sec 
R = 1 sec 
R = 0 sec 
Discussion:
Take
a few minutes to review the phasing plan with the exclusive pedestrian
phase. By moving the pedestrians to their own phase, will they be assigned
more or less time than they were before? What benefits are derived by
assigning pedestrians with an exclusive phase? Click continue when you are ready
to proceed.
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