Using Panel Data Analysis to Evaluate How Individual Non-Pharmaceutical Interventions Affected Traffic in the US during the First Three Months of the COVID Pandemic

In response to the COVID-19 pandemic, restrictive non-pharmaceutical policy interventions (NPIs), with the goals of reducing interactions and travel for people in different households, were introduced. In the U.S., each state had jurisdiction over the NPI policy imposed, resulting in myriad policy decisions. The aggregate impacts of these decisions are known; however, the individual impacts are not fully understood. We disaggregated the NPIs imposed during the first three months of the epidemic (1 March and 7 June 2020) using panel data regression analysis. Vehicular travel reduction as a proxy for NPI impacts on traffic was regressed against stay-at-home orders, business closures, school closures, and gathering bans. The results show that school closures and full closures of non-essential businesses were correlated with the largest impacts in reducing vehicle trips compared to when they are not in place. Stay-at-home orders had about half the impact of school closures compared to when they were not in place. Gathering bans had the least impact. In the U.S., decisions that target businesses were the most effective in reducing vehicle traffic. There was heterogeneity in how people responded to these restrictions. This study can be used in epidemiology models and inform decision-makers on policies that work best.