October 25, 2018

This week, Washington, DC Mayor Muriel Bowser’s administration announced a number of plans to rethink the flow of traffic on the city’s streets. These plans followed an announcement earlier in the year that the city would create an Office of Vision Zero staffed with professionals and safety experts dedicated to helping the city reach zero traffic-related fatalities and serious injuries by 2024.

Among the proposed plans are the following:

• Banning right turns on red at 100 locations
• Implementing design changes to reduce left turn speeds
• Expanding designated drop-off and pickup zones for ride-hailing services, delivery vehicles, and private drivers
• Reducing neighborhood speed limits from 25 mph to 20 mph
• Requiring DC driver’s license holders to take a refresher course on road rules, with elements emphasizing awareness of pedestrians, bicyclists, and scooter riders

The Mayor’s proposal attempts to address the fact that new mobility options have shifted the way that urban streets function today. Uber and Lyft have dramatically increased demand for curb access, often obstructing car, bike, and bus traffic. E-commerce has created demands for large delivery trucks on the streets. The growing popularity of bicycles and bike- and scooter-share systems have increased traffic conflicts, while outdated policies can encourage bicyclists to run lights and use sidewalks.

As cities begin to explore ways to accommodate new forms of mobility, outdated traffic laws and regulations must similarly shift to ensure everyone’s safety. Washington DC’s plans represent an opportunity for the city to reinvent the “rules of the road” by developing appropriate updated regulations that are fair and beneficial to all users.

Evaluating the effects of new rules

Cities around the country have begun to explore similar tactics in an effort to adjust to new travel patterns. These strategies are in various stages of implementation, but evaluations are beginning to demonstrate their benefits.

In January 2017, Boston reduced its default city street speed limit from 30 mph to 25 mph. In an evaluation of vehicle speeds before and after the new limit took effect, researchers at the Insurance Institute for Highway Safety (IIHS) found that there was a 29.3 percent decline in the odds of a vehicle exceeding 35 miles per hour, an 8.5 percent decline in the odds of a vehicle exceeding 30 miles per hour, and a 2.9 percent decline in the odds of a vehicle exceeding 25 miles per hour. The next phase of the research will assess whether the lower speed limit affects the rate of crashes in Boston. Citing Fatality Analysis Reporting System data, IIHS reports that the percentage of crash deaths related to speeding was higher on urban roads with posted speeds of 35 mph or less than on roads with higher speed limits in 2016 (31 percent vs. 25 percent, respectively).

Since 2016, New York City has installed over 200 treatments to city intersections in an effort to reduce left turn speeds. Typically, these treatments take the form of rubber curbs and bollards along the centerline of an intersection, meant to slow drivers and prevent collisions with pedestrians, bicyclists, and vehicles. The NYC Department of Transportation (NYCDOT) found that these treatments have resulted in a decrease in average left turn speeds by 20.5 percent and a drop in crossing the double yellow line while turning by 78.9 percent or 100 percent, depending on the type of treatment. NYCDOT is still collecting before and after crash data, which will help the city better understand the treatments’ effects on injuries and fatalities.

Maximizing the benefits of new rules of the road

In order to achieve safer streets, cities must be willing to enforce new rules of the road. Washington DC has proposed a variety of enforcement tactics—citing drivers that block intersections and bike lanes, increasing red-light cameras, and reducing the time required to process tickets—to complement its infrastructure and policy-based safety strategies. Traffic violation enforcement is critical to maintaining safe streets, but cities should ensure that it is done equitably.

In addition, cities should vigorously collect data on how streets are being used and whether certain strategies improve safety. Cities are already beginning to partner with the private sector to gain access to data on shared mobility services, with the goal of understanding how those services are used on streets. This information can help planners and policymakers, for example, design spaces to be used by ridehailing services, delivery vehicles, and dockless bikes and scooters, decide whether to expand bike lanes in corridors of frequent bike use, and monitor points of collision as possible candidates for safety infrastructure improvements.

Cities can then clearly define the desired outcomes of their new rules of the road, and monitor new treatments for their effectiveness in achieving these outcomes. Potential outcomes that cities might consider are measurable reductions in roadway collisions, measurable increases in walking and biking trips, and measurable decreases in speeding and other moving violations. Cities should devise rules and infrastructure improvements aimed at achieving the desired outcomes, as in the cases described above, and should actively assess and report on whether the policies and treatments help to achieve those outcomes.

Mobility is changing. To keep up with these changes and to achieve the safe movement of people will require cities to seriously consider redefining the rules of their roads, to implement bold strategies that better accommodate all road users, and to assess the effectiveness of these strategies. The proposed changes in DC have the potential to significantly increase safety. Research shows that these gains will only be realized if the city prioritizes fair enforcement and a commitment to evaluating and, if appropriate, expanding these new rules.

The opinions expressed above are those of the author and do not necessarily reflect those of the Eno Center for Transportation.