Transit service interruptions due to mechanical failures remained relatively level from 1995 through 2000, averaging 13 mechanical problems per 100,000 revenue vehicle-miles. However, between 2001 and 2003-after the definition of service interruption changed in 2001-motor bus interruptions of service declined such that total transit interruptions averaged 8 mechanical problems per 100,000 revenue vehicle-miles.1 Buses had the largest change in reported interruptions after 2001, averaging between 24 mechanical problems per 100,000 revenue vehicle-miles after the reporting change as opposed to averaging 38 mechanical problems per 100,000 revenue vehicle-miles prior to 2001 [1, 2] (figure 12-5).
Among transit vehicles, buses and light rail had the highest rates of mechanical failure in 2003. Buses broke down an average of 22 times per 100,000 revenue vehicle-miles, while light-rail vehicles broke down 14 times per 100,000 revenue vehicle-miles. Light-rail vehicle breakdowns have changed the most since 1995. In that year, there were 33 mechanical failures per 100,000 revenue vehicle-miles. The rate of failure then dropped 56 percent to 15 per 100,000 revenue vehicle-miles by 2000. During this period, the number of light-rail revenue vehicles increased 58 percent from 999 vehicles to 1,577 vehicles.
1. U.S. Department of Transportation, Federal Transit Administration, National Summaries and Trends (Washington, DC: Annual issues), also available at http://www.ntdprogram.com/, as of April 2005.
2. U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, National Transportation Statistics 2004 (Washington, DC: 2005), table 1-32 and Transit Profile, available at http://www.bts.gov/, as of April 2005.
1 Data prior to 1995 and later than 2000 were collected using different definitions of what constitutes an interruption of service and are not comparable. For 2001 data and later, for instance, if the vehicle operator was able to fix the problem and return the vehicle to service without assistance, the incident is no longer considered an interruption of service.