This paper summarizes the detailed heavy vehicle traffic flow on expressways for three months from March 11, 2011 as a result of the Great East Japan Earthquake. Day-by-day traffic changes, compared with historical data, and analysis together with related statistics showed the following results: The Western route called Kan-etsudou experienced 20% increase in traffic caused by detour trip toward the disaster region Tohoku during the first week. From the fourth week until mid-July after the earthquake, the average traffic volume increased by 20% compared with 2010, and average trip length increased by 10%. One of the major reasons for this change was that ports in the Tokyo Bay area were used as alternative freight transport routes in place of damaged ports in Tohoku. The influence of the disaster to the Tokyo Metropolitan Expressway network was quite limited.
