By Chris McCahill
The U.S. DOT is funding bus projects across the country that promise many of the same benefits as rail, but at lower cost. With dedicated lanes and stations that are more like train stops than a typical American bus stop, bus rapid transit (BRT) aims to move large numbers of people through congested areas faster than rush hour traffic. This sometimes comes with tradeoffs, like the loss of regular traffic lanes, but it can also offer unanticipated safety benefits, like curbing excessive traffic speeds, according to new research.
Albuquerque Rapid Transit opened in 2019 and boosted ridership along Central Avenue by at least 30% in the months leading up to the pandemic. However, that launch came after more than a year during which the new bus lanes sat empty due to operational problems. While unfortunate for riders, the delay presented an opportunity for researchers at the nearby University of New Mexico.
Using vehicle probe data from StreetLight Data, they studied the impact of BRT infrastructure on vehicle speeds and found significant decreases along the corridor, even without buses running. Overall, 85th percentile speeds dropped 11.5% from 32.3 mph to 28.6 mph. This suggests, “that the BRT infrastructure is especially effective at limiting excessive speeding,” according to the authors. Speeds also dropped on comparable roads without new bus infrastructure, but by a smaller margin of around 5.8%.
The effects were largest at intersections along the BRT route and in places where the number of general-purpose lanes was reduced. Average vehicle speeds dropped by around 15% when there was a lane reduction, versus 10% at other locations, and 85th percentile speeds dropped by 12% to 14%, versus 8% at other locations. Unfortunately, vehicle speeds did not change much on the fastest roads with speed limits posted at 40 mph. “There likely remained a culture of high speed at the 40 mph sites,” according to the researchers.
The researchers explain the importance of these findings:
“Although arterial corridors are host to most cities’ traffic safety issues, most traditional traffic-calming approaches are not applicable because they would degrade traffic operations to a point of failure. Converting arterial corridors to more multimodal arrangements can provide road users with mobility options while simultaneously improving safety outcomes.”
The authors note that research has shown similar safety benefits in cities that installed protected bike lanes. Another recent study confirms drivers slow down based on design cues like trees, buildings, painted bike lanes, and unmarked travel lanes. This all points to the importance of multimodal design and what are sometimes called “self-explaining roads” in creating a culture of safety on urban streets.
Photo Credits: Scott Szarapka via Unsplash, unmodified. License.