DC Moving Violations

An investigation of more than six million moving violation citations in Washington, DC found that the average number of monthly traffic stops by live officers declined dramatically during the pandemic–and have not returned to pre-pandemic levels.

Data was extracted via Open Data DC’s application programming interface (API) and analyzed using Python, pandas and matplotlib. The data contains 6,784,751 unique ticket numbers spanning from January 1st, 2017 to December 31st, 2021. Moving violations issued by automated traffic enforcement (ATE) cameras were identified by the first character of the ticket number: those with ‘F’ or ‘D’ were marked automated. 300,300 hand-written tickets were identified, with the remaining 6,484,450 issued by ATE.

This chart tracks monthly citations issued by the city’s 138 ATE cameras (in red on the right axis) against citations issued by by officers of MPD and the 40 or so other agencies reporting this data to DC Department of Motor Vehicles (in blue on the left axis).

The two horizontal lines represent the historical averages before and after the onset of the pandemic. From January 2017 to the end of March 2020 the average number of traffic citations issued per month by an officer-initiated traffic stop was 6,127. In the period from April 2020 to the end of 2021 that number was 2,922 — a 52% decrease.

In contrast, the ATE cameras increased their monthly count from an average of 101,427 pre-pandemic to 120,419 thereafter. This may be explained by new ATE cameras being deployed, although the press office at the District Department of Transportation only has press releases announcing eight new cameras in June 2021.

This drop off in traffic stops might have been a function of lower traffic volume from COVID-19 shutdowns in 2020. Data from the Federal Highway Administration provides a monthly estimate of traffic volume across the country, collected from continuous traffic counting locations nationwide.

Dividing each month’s mean of moving violations by each month’s traffic volume gives a metric of traffic stops per unit of traffic volume. The pre-pandemic mean of stops per unit of traffic volume was 19.84; post-pandemic onset the mean dropped to 15.96 — a drop of nearly 20%.

Despite reporting errors in the data (no data at all was reported for February 2017), the evidence looks strong that MPD and other law enforcement organizations have not returned to pre-pandemic traffic enforcement levels, automated systems not withstanding.