Time lag effects of COVID-19 policies on transportation systems: A comparative study of New York City and Seattle

Zilin Bian, Fan Zuo, Jingqin Gao, Yanyan Chen, Sai Sarath Chandra Pavuluri Venkata, Suzana Duran Bernardes, Kaan Ozbay, Xuegang (Jeff) Ban, Jingxing Wang

Research output: Contribution to journalArticlepeer-review


The unprecedented challenges caused by the COVID-19 pandemic demand timely action. However, due to the complex nature of policy making, a lag may exist between the time a problem is recognized and the time a policy has its impact on a system. To understand this lag and to expedite decision making, this study proposes a change point detection framework using likelihood ratio, regression structure and a Bayesian change point detection method. The objective is to quantify the time lag effect reflected in transportation systems when authorities take action in response to the COVID-19 pandemic. Using travel patterns as an indicator of policy effectiveness, the length of policy lag and magnitude of policy impacts on the road system, mass transit, and micromobility are investigated through the case studies of New York City (NYC), and Seattle—two U.S. cities significantly affected by COVID-19. The quantitative findings show that the National declaration of emergency had no policy lag while stay-at-home and reopening policies had a lead effect on mobility. The magnitude of impact largely depended on the land use and sociodemographic characteristics of the area, as well as the type of transportation system.

Original languageEnglish (US)
Pages (from-to)269-283
Number of pages15
JournalTransportation Research Part A: Policy and Practice
StatePublished - Mar 2021


  • COVID-19
  • Change point detection
  • Lessons learned
  • Policy lag
  • Time effect

ASJC Scopus subject areas

  • Aerospace Engineering
  • Business, Management and Accounting (miscellaneous)
  • Transportation
  • Civil and Structural Engineering
  • Management Science and Operations Research


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