Influence of trip distance and population density on intra-city mobility patterns in Tokyo during COVID-19 pandemic

Abstract

This study investigates the influence of infection cases of COVID-19 and two non-compulsory lockdowns on human mobility within the Tokyo metropolitan area.Using the data of hourly staying population in each 500m×500m cell and their city-level residency, we show that long-distance trips or trips to crowded places decrease significantly when infection cases increase. The same result holds for the two lockdowns, although the second lockdown was less effective. Hence, Japanese non-compulsory lockdowns influence mobility in a similar way to the increase in infection cases. This means that they are accepted as alarm triggers for people who are at risk of contracting COVID-19.

Sustaining self-restraint until the middle of the COVID-19 pandemic in Tokyo

“…It can also be confirmed that, in the second wave (around July-September 2020), the change in mobility remained smaller than in the first wave. This result is consistent with the findings of existing studies 19,20 . Note that the variation of the partial regression coefficient and the adjusted R 2 in August may be largely attributable to the summer vacation.…”

“…Figure 1 depicts the number of COVID-19 cases in Japan and the period during which a state of emergency was declared as the period analyzed by this study 7 . Despite the request for voluntary travel restraint without legally binding force, existing studies have shown that the mobility behaviors of people in Japan have changed significantly compared to the pre-COVID-19 period [8][9][10][11][12][13][14][15][16][17][18][19][20] . It is important to understand how the voluntary lockdown has changed travel behaviors to determine urban development and transportation policies during and after COVID- 19.…”

“…Several studies in recent years have examined mobility changes in Japan using location data collected from mobile phones 9,10,14,[18][19][20][21][22] . Studies of mobility change based on web-based questionnaires can reveal detailed changes in mobility characteristics over a specific period 8,15,23 while studies using mobile phone data can reveal sequential mobility changes.…”

“…Studies of mobility change based on web-based questionnaires can reveal detailed changes in mobility characteristics over a specific period 8,15,23 while studies using mobile phone data can reveal sequential mobility changes. Although there are multiple sources of mobile data used to study mobility change 9,18,21,24,25 , mobile spatial statistics (MSS) data 26 are commonly used in Japan 10,14,19,20,22 . MSS data are population statistics created from the operational data of mobile terminal networks provided by NTT docomo, which is the largest carrier in Japan, holding 37.5% of mobile phone contracts 10 .…”

“…Previous studies have revealed statistical mobility changes in people before and after the COVID-19 pandemic. For example, an increase in the number of infected people significantly reduced long-distance travel and travel to congested places 20 , and the first wave of the pandemic receded because of a significant decrease in travel as a direct result of the request for self-restraint 19 . Studies using Japan's MSS data have provided detailed analyses of mobility changes that cannot be revealed by aggregated data such as the Google Mobility Report 21 , which provides an excellent overview of behavioral change.…”