- Time restrictions on shared micromobility vehicles such as electric scooters and bikes can increase traffic congestion and emissions, according to a study published in Nature Energy last week by researchers at the Georgia Institute of Technology.
- Travel time in Atlanta increased from 9% to 11% in the city center and near transit hubs after the city prohibited e-scooter and e-bike rentals from 9 p.m. to 4 a.m. daily, the study found. Atlanta unexpectedly banned the nighttime use of shared micromobility vehicles in 2019 to address public safety concerns, creating a natural experiment for researchers to study the effects of such bans on traffic and pollution.
- "To accelerate the adoption of micromobility and achieve its associated sustainability benefits, we argue that cities will need to make additional investments in both physical and digital infrastructure," the study says.
Some micromobility advocates, policymakers and researchers have claimed that e-scooters and e-bikes curb traffic congestion and tailpipe emissions by reducing car use. The evidence supporting those claims up to now relied on surveys and simulations that used small data sets, leading to mixed findings, according to the researchers.
This is the first study to evaluate the effects of shared e-scooter and e-bike time restrictions in the real world, said study co-author Omar Asensio, a public policy professor and director of Georgia Tech's Data Science and Policy Lab, in an interview.
The researchers used data from Uber Movement to study how the restrictions affected traffic congestion and emissions. The ban resulted in "near perfect compliance" thanks to GPS-enabled mobile geofencing and remote shutdown, according to the study. Shared micromobility vehicles from every provider became unavailable in mobile apps during prohibited hours, the study says. It became almost impossible to rent and ride an e-bike or e-scooter in Atlanta immediately during the restricted hours, Asensio said.
The researchers studied the ban's effects on passenger vehicle travel time near the city center, transit hubs such as subway stations, and Mercedes-Benz stadium, which hosts Major League Soccer games and other events.
After analyzing the 45-day periods before and after the policy took effect, the researchers found that traffic congestion peaked in the city center and near transit hubs within the first week following the ban. It declined in the following weeks as residents adjusted to the policies and adopted new travel patterns, but traffic congestion remained higher than before the ban, the study found. Traffic congestion after large events such as MLS games increased 37% during the study period.
The findings suggest that people often replace micromobility with passenger cars rather than walking, taking public transit or using other lower-emission transportation, according to the researchers.
While those effects may differ by city or region, given the wide variation in transportation systems and mode mixes, micromobility restrictions likely increase traffic congestion and, in turn, emissions in most areas, Asensio said. People often use scooters or e-bikes to travel the last mile of their trip when they use public transit, making them more likely to drive the entire trip or use a ride-hailing service for the end of their journey rather than walk when there are no scooters or e-bikes available, he said.
"Even if you have better public transit, that's not going to change that mechanism of getting into the subway, getting out and riding a scooter. That's fundamentally the same," Asensio said.