Electric scooters, one of the fastest-growing forms of urban transportation, are reshaping city mobility in unexpected ways, and it includes an increase in crime.

A team from the University of Illinois Urbana-Champaign launched the study following the introduction of shared e-scooters in Chicago, which boosted demand for ridesharing services but reduced bikeshare usage. It has also been linked with higher rates of street and vehicle-related crime in neighbourhood according to new research co-authored by Unnati Narang, a professor of business administration at the Gies College of Business.

The results of the study, which was co-authored by Unnati Narang, (pic) a professor of business administration at the Gies College of Business in a joint project with Ruichun Liu of San José State University and a former Illinois graduate student, challenge common assumptions about the benefits of e-scooters.

“E-scooters are hailed as an environment-friendly innovation that is spurring retail activity, but their impact goes beyond what we know in the marketing literature,” Narang explained. “Our study is the first to document the effects of e-scooters beyond retail and restaurants and show how they are reshaping shared mobility systems and even public safety in ways that policymakers need to take seriously, because they accrue economic and environmental costs.”

The researchers analysed the introduction of e-scooters in Chicago during the summer of 2019, when the city allowed 10 companies to deploy e-scooter rentals across a 50-square-mile area on the west and northwest sides of the city.

Using data from more than eight million rideshare trips, 750,000 bikeshare rides and detailed crime reports across 866 census tracts, they applied a statistical method known as “generalised synthetic control” to measure how e-scooter access changed travel and crime patterns compared to similar neighbourhoods without them.

E-scooter availability led to a 15.7% increase in short rideshare trips, but bikeshare programs saw a 7.6% decline in trips in areas with scooter access, suggesting that riders often substituted e-scooters for rental bikes.

“The increased rideshare trips from e-scooters reflects what we call a category expansion effect,” said Narang, the John M. Jones fellow of marketing and Deloitte scholar. “E-scooters encourage people to take trips they might not have otherwise made, often combining trips with ridesharing. For example, riding an e-scooter to dinner, then calling a rideshare vehicle to get home. Or going to the grocery store but needing a ride back with grocery bags. But we also found that e-scooters don’t add to bikeshare demand. They directly compete with it, which is a classic case of category cannibalisation despite greater need for new trips overall.”

While e-scooters expanded mobility and generated new economic activity, they also coincided with a 17.9% rise in reported crimes, concentrated in street and vehicle-related offenses such as car break-ins and thefts.

The researchers emphasised that this rise in crime represents a hidden social cost that cities should consider when evaluating urban transportation policies.

“E-scooters are portable and fast, which makes them attractive tools for crimes of opportunity,” Narang explained.

Despite their eco-friendly image, e-scooters also may not yield environmental gains because they spur an increase in short rideshare trips instead of replacing them.

“Policymakers often see e-scooters as a green alternative, but because they increase short rideshare trips rather than substituting for them, their net environmental effect is negative,” Narang said. “In fact, we found that although rented e-scooters contributed about $8.1 million in ridesharing revenues, they also had an unintended negative environmental effect amounting to over 800 metric tons of carbon emissions per year.”

To offset that volume of annual emission, “you’d need around 36,000 trees growing for one full year,” Narang said. “You can explain the trade-off with other similar environment initiatives and some quick back-of-the-envelope calculations.”

The findings highlight the need for more nuanced e-scooter regulation, the researchers said. Cities may need to invest in protected lanes, adopt safety campaigns, rollout strategies that limit crime opportunities and engage with communities to ensure equitable benefits, according to the paper.

“Cities should not assume that e-scooters automatically promote sustainability or level the playing field in terms of mobility,” Narang said. “They create a lot of externalities, and regulation and planning must address safety and fairness head-on.”

E-scooter availability led to a 15.7% increase in short rideshare trips, but bikeshare programs saw a 7.6% decline in trips in areas with scooter access, suggesting that riders often substituted e-scooters for rental bikes.