183 Impact of COVID-19 lockdown on vehicle speed in Mumbai City, India: an interrupted time series analysis

<h3>Background</h3> Road traffic injuries are a significant public health challenge, particularly in an emerging economy like India. The onset of the COVID-19 pandemic and subsequent lockdowns provided a unique opportunity to study changes in traffic behaviors, especially overspeeding, a leading factor of crashes and fatalities. <h3>Objective</h3> This study uses an interrupted time series analysis to investigate the impact of the COVID-19 lockdown on vehicle speed in Mumbai City, India. <h3>Methods</h3> Since 2015, the Johns Hopkins International Injury Research Unit has collaborated with the Indian Institute of Technology Bombay to collect roadside speed observation data in Mumbai City. Using the speed data from 695,979 vehicles from 14 rounds of surveys (2015–2024), we implemented a segmented multi-level linear mixed effects model to estimate the impact of the COVID-19 lockdown, initiated on 25th March 2020, as the intervention point on the average speed of vehicles on arterial roads. <h3>Results</h3> In 2015, the average speed of vehicles was 40.33 km/h, and 21.78% of them exceeded the posted speed limit on arterial roads in Mumbai City. In 2019, both the average speed and speeding prevalence significantly reduced to 37.44 km/h and 8.67%, respectively. This indicated an average speed reduction of 0.47 km/h (p&lt;0.001) every month between 2015 and 2019. However, there was a significant increase in average speed by 3.50 km/h (p&lt;0.001) immediately after the pandemic, and the speeding prevalence surged to 30.40% in Mumbai in 2021. Subsequently, a significant but attenuated decreasing trend of average speed was observed at a rate of about 0.06 km/h (p=0.04) per month, suggesting a rapid post-pandemic adaptation in driving behaviors. <h3>Conclusions</h3> The COVID-19 lockdown significantly impacted the average speed and the number of vehicles exceeding the posted speed limit in Mumbai, initially causing a spike, followed by a notable deviation from the previous secular downward trend. These shifts underscore the dynamic nature of traffic behavior in response to major societal disruptions. This study highlights the importance of adaptive traffic management and policymaking, particularly during public health emergencies, and contributes to integrating traffic safety within broader road safety and policy discourse.