How did the COVID-19 pandemic affect driver speed selection and crash risk on rural freeways?

Abstract

The COVID-19 pandemic disrupted various aspects of day-to-day life in unprecedented ways. This included significant reductions in travel that corresponded with travel restrictions imposed to contain the spread of the virus. This study evaluated changes in driver speed selection and crash/injury risk over the course of the pandemic on rural freeways in Michigan. Daily speed data and monthly crash data were analyzed from 2015 to 2020 to investigate changes that corresponded to the onset of the COVID-19 pandemic. The results showed that during the initial periods of lockdown, mean speeds increased by 2.2–2.4 mph across all sites, while the total crash frequency was lower by 28%–45% compared to pre-pandemic years. Crashes also tended to be significantly more severe during the early stages of the pandemic. Interestingly, these changes were less pronounced on sites with 70-mph speed limits as compared to sites where speed limits were increased to 75 mph in 2017. However, as travel restrictions were lifted, speeds regressed towards long-term averages on the 75-mph sites while the higher speeds were maintained at sites with 70-mph limits. The increase in injury severity appears to be attributable to higher speeds, as well as increases in other high-risk behaviors during the pandemic, such as non-use of seat belts and driving under the influence of drugs or alcohol. Some of these effects are also due to differences in terms of the population of drivers that were on the road during the pandemic. The results provide important insights as to the increases in severe crashes that coincided with the onset of the pandemic.