Japanese travel behavior trends and change under COVID-19 state-of-emergency declaration: Nationwide observation by mobile phone location data

In the early stages of the COVID-19 pandemic, the Japan government could not impose strong restrictions such as lockdowns. Since there has been no such nation-wide behavioral analysis, we calculated indicators of nation-wide behavioral change using data based on mobile phone network.This study shows empirical facts and findings on behavioral changes under COVID-19 “state-of-emergency” declarations in Japan that are obtained by using mobile terminal network operational data. Results show that a significant reduction in trips and inter-prefectural travel was achieved without strong restrictions by the government. In addition, the population density index decreased by 20% and people avoided traveling to densely populated areas. This analysis shows that once people’s behavior is changed by the declaration of a state of emergency, it does not return to normal immediately after the lifting of the declaration; rather, it recovers slowly.