UMaine study shows why lane departure accidents are so prevalent in Maine

In Maine, lane departure crashes, such as running off the road or head-on collisions, are the most prevalent source of road fatalities, accounting for nearly 70% of roadway deaths. A new study from the University of Maine shows how rural roads, deteriorating infrastructure, an aging population and cold weather can be a deadly combination for drivers.

Ali Shirazi, assistant professor of civil and environmental engineering, led a study published in February 2023 in the Journal of Safety Research about the factors influencing lane departure crashes as part of a project sponsored by the Maine Department of Transportation. The study analyzed the impact of roadway, driver and weather factors on the severity of single-vehicle lane departure crashes — ranging from fatal crashes to only property damage — that occurred between 2017 and 2019 on various types of roadways in Maine. 

“Lane departure crashes account for nearly 70% of roadway fatalities in Maine; and a vast majority of those are single vehicle crashes. It is therefore crucial to understand factors that impact road departure crashes to develop countermeasures or interventions to reduce the number or severity of these crashes,” Shirazi says.

The researchers used weather data from National Oceanic and Atmospheric Association (NOAA) stations, and considered groups of variables like the driver’s age, sex and whether they were speeding, operating under the influence or using their seatbelts; when the crash happened; the vehicles involved in the crash; and the roadway characteristics where the crash occurred, such as curves, speed limits and lane width. 

By modeling these variables together, researchers found that the odds of crashes increases as much as three times for older drivers above the age of 65 compared to young drivers aged 29 or less on all types of Maine roads. Still, failure to use a seatbelt was the most influential variable causing severe injuries. 

“In Maine, factors such as older drivers, operating under the influence, speeding, precipitation, and not wearing a seatbelt showed higher odds of leading to injury,” says Shirazi.

The researchers hope that this study will help MaineDOT and cities and towns throughout the state improve their maintenance strategies, enhance safety by using proper countermeasures and increase awareness of the factors causing accidents across the state.

“The findings of this study provide insights for safety analysts, practitioners and agencies in Maine to better understand the factors impacting lane departure crash severities on rural roads. Removing utility poles and trees from the clear zone and beyond, and enforcing speed limits would be effective in reducing fatalities and serious injuries when people do go off the road. Providing guardrails where trees cannot be removed is an alternative,” says Shirazi.

The study’s co-authors include Per Garder, professor of civil and environmental engineering; and Jonathan Rubin, professor of economics; and former graduate student Alainie Sawtelle.

Contact: Sam Schipani,