A program to reduce traffic congestion near 30th Street Station placed PPD officers to direct traffic at the intersection of Schuylkill Avenue and Market Street and at the intersection of 30th Street and Market Street. Officers were present on Thursdays and Fridays from September 27 and November 16, 2018 between approximately 2:30pm and 6pm.

Below is an evaluation of travel times on street segments directly adjacent to the two intersections at which police directed traffic. Travel times at times when police were present (blue in figure below) were compared to a comparable period of equal length (also Thursdays and Fridays between 2:30pm and 6pm) preceding the period when traffic police started.

On almost all street segments adjacent to intersections where police directed traffic, travel times increased when police were present compared to the preceding periods (differences on Market Street between Schuylkill Avenue and 30th Street were not significant at \(\alpha\)=0.05). However, we are unable to say that the increased travel delays shown below are related to the presence of traffic police.


Several University City and Center City streets that we evaluated experienced higher travel times during the period when traffic police were present compared to the preceding baseline period. Below, “treatment streets” refer to the six street segments directly adjacent to the intersections where police were present (blue). “Control streets” refer to approximately 200 other street segments where travel time data were also collected (green bars in figure below).

A majority of the approximately 200 control streets evaluated also experienced increased travel times during the time period when traffic police were present around 30th Street Station. Therefore, it is difficult to make a conclusive statement about the efficacy of traffic police presence in decreasing travel times in this portion of University City; it is only possible to conclude that if police did help combat congestion, the effects were not strong enough to overcome any slowing trends already occuring during that time period.



Below, median speeds are compared between streets around the 30th Street District (those possibly affected by the presence of traffic cops) and “Control streets,” or streets elsewhere in University City that are likely not affected by the presence of traffic cops. Notice the change below to speeds (mph) from travel times (seconds) which were used above (because multiple streets are aggregated, speed is a more appropriate measure, as travel times are corrected by distance). In the figure below, the blue rectangle represents the weeks when traffic cops were present around 30th Street Station. The below data include rush hours on Thursdays and Fridays.

Speeds on control streets are consistently higher than speeds on streets around 30th Street Station over the year (including the weeks when traffic cops were present, with the exception of weeks 45-46). Speeds spike immediately after the end of the period when traffic cops were present, likely due to Thanksgiving.

With the available data, it is not possible to make a conclusive claim that the presence of traffic police contributed to lessened congestion.



Below, median speeds are compared between streets around the 30th Street District and “Control streets,” or streets elsewhere in University City in 2017 rather than 2018 (No traffic cops were present in 2017, but the use of the term “control streets” was maintained for consistency). The trend of speeds around 30th Street Station being slower than elsewhere is a trend that continued from 2017.



Below, median speeds around 30th Street Station are compared between 2018 and 2017. The blue rectangle represents the period during which traffic cops were present. Annual trends do not suggest a clear effect of traffic cops on travel speeds in 2018.