Transit Information Center
Effects of traffic congestion on average commuting time per unlinked passenger trip (Bus)
Data sources:
Systems: WMATA - Washington DC, LACMTA - Los Angeles, Miami Dade Transit - , Pittsburgh, SEPTA - Philadelphia, NYCTA - New York, NJT - New Jersey, King County - Seattle, CTA - Chicago, Dallas - Fort Worth, - Houston
National Transit Database: http://www.ntdprogram.gov
For the purpose of this study, we looked at 11 bus systems (1) operating in large urban areas between 1987 and 2007. The average commuting time was determined for the period using National Transit Database (NTD) data (2). The data includes vehicle travel time only.
One possible reason for the increase in average commuting time might be an increase in average trip length over the period. However, an analysis of the data reveals that the average trip length of these 11 systems did not change much over the same period, as illustrated in the second graph.
In looking at the data, it is reasonable to assume that worsening traffic congestion in these areas was the main factor contributing to the increase in average commuting time.
By applying linear regression to the data, we estimated that when comparing 1987 with 2005, there was an increase of 2.6 minutes in the average commuting time per unlinked passenger trip.
For more information, contact the Transit Information Center (ticinfo@tspusa.com).