Signal Timing

In 2012, Feet First Philly undertook a series of intersection field surveys, based on the frequent expressions of concern about adequate time to cross the street, which were voiced at early meetings of the group.

This project found that most of the intersections surveyed provided adequate time to cross the street, both in practice and according to the federal guidelines set out by the Manual on Uniform Traffic Control Devices (MUTCD).  These guidelines state that, where there is a pedestrian signal, a pedestrian walking at 3.5 ft/sec should be able to cross safely if he or she begins crossing at or before the beginning of the countdown phase.  The timing allows for pedestrians to complete their crossing during the yellow phase and the all-red phase. In cases where a pedestrian signal is absent, a person should be able to cross at a walking speed of 3.0 ft/sec if he or she begins crossing when the light turns green.  Signal timing for pedestrians is primarily based on street width.  Slower pedestrian speeds should be used if a signal serves persons with diminished walking capacity.

A total of 15 intersections were studied using a survey tool devised by Clean Air Council staff, with input from members of Feet First Philly.  Surveyors recorded general observations related to walkability, signal timing, and pedestrian counts.  Below is a list of intersections studied for the project.  These intersections were selected based on their locations in Center City, responses to the online survey question pertaining to “problem intersections”, and other characteristics.

Table 1: Intersections studied

20th and Benjamin Franklin Parkway

20th and Ben Franklin Parkway
19th and Market
15th and Market
20th and Market
20th and JFK
Broad and Walnut
16th and Chestnut
8th and Market
2nd and Market
Broad and Locust
Juniper and Market (east of City Hall)
Broad and Girard
9th and Chestnut
9th and Market
10th and Arch

 

While most of the intersections studied met the minimum requirements for pedestrian crossing time, a few crossings were just at the threshold.  These intersections should be prioritized when making intersection improvements to ensure that they remain safe for pedestrians.

Table 2: Intersections where crossing time may be a problem for some individuals

Street crossing Time required Time observed Difference
Market @ 19th 17.1 seconds 16.6 seconds -0.5 seconds
Broad @ Walnut 21.4 21.4 0.0
20th @ JFK 15.7 15.8 0.1
JFK @ 20th 16.0 17.2 1.2

Observed conditions at the intersections studied indicate that “difficulty crossing” ” is not only due to the signal timing.  Turning cars often fail to yield to pedestrians in the crosswalk. Aside from the fact that this risks causing a collision with a pedestrian, it can prevent pedestrians from using the time allocated for crossing, and leave them stranded in the crosswalk.

At some intersections (where a median of five feet wide or greater is present), pedestrian clearance time only needs to be sufficient for pedestrians to reach the median.  Many pedestrians either are unaware that they may be expected to wait on the median refuge island for a second chance at the Walk signal, or they may be uncomfortable standing on a five-foot median in the middle of a street with heavy traffic volumes and/or relatively high speeds.

 

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