Minutes Matter: A Guide to Bus Transit Service Reliability

The Transit Capacity and Quality of Service Manual (TCQSM) lists the following factors as influencing reliability: traffic conditions and road construction; vehicle and maintenance quality; vehicle and staff availability; transit preferential treatments; schedule achievability; evenness of passenger demand; variations in bus operator experience; wheelchair lift and ramp usage; route length and the number of stops; and operations control strategies. Weather—particularly snow and extreme temperatures—also plays a role. These factors have been addressed individually by research to some degree—for example, operations control strategies, scheduling, bus operator experience, route length, and applications of Automatic Vehicle Location and other technologies—but there is no comprehensive research that addresses all these factors in combination. Bus service reliability is a key quality-of-service issue for passengers, an important driver of bus operations costs for transit agencies, and a health and safety issue for bus operators. From the passenger point of view, unreliable service means that customers must allow extra time for their trip to make sure they arrive at their destination by a particular time—minimizing lost time that could otherwise have been used more productively. Although a typical rule of thumb is that passengers perceive wait time as being twice as onerous as in-vehicle time, recent research indicates that transit passengers perceive unexpected wait time as being 3 to 5 times as onerous as in-vehicle time. In contrast, automobile travelers value travel time unreliability (i.e., unexpected delay) at approximately the same level that they value travel time, suggesting that transit service is at a competitive disadvantage with the automobile with respect to unreliable travel times. From the transit agency point of view, travel time variability impacts a route’s cycle time and, ultimately, operating cost. Poor reliability (or unreliability) can increase labor costs. In a best-case scenario, reduced cycle time resulting from reduced travel time variability allows a bus to be removed from a route while maintaining scheduled headways. Conversely, if reliability issues are not addressed, a transit agency eventually needs to add buses to a route (increasing costs) or decrease bus frequency. From the bus operator point of view, unreliable service can lead to adverse effects such as increased assaults, operator fatigue, and fewer opportunities to use facilities. This condition may result in lost time, directly affecting operator availability and, ultimately, service reliability. Research is needed to develop guidance on measuring and valuing (a) reliability from the passenger, operator, and agency points of view; (b) the effects of potential operational, technological, and physical measures to improve reliability in particular situations; and (c) the potential benefits and costs of those actions. Accurately estimating the benefits of reliability-improvement measures is necessary for transit agencies, both to gain the acceptance of roadway-owning agencies to implement certain treatments (e.g., bus stop relocation or removal, traffic signal priority, queue jumps, street maintenance) and to compete for scarce transportation funds to implement improvements on a large scale (e.g., along an entire route or throughout a city). A guide on improving bus transit reliability would identify cost-effective techniques for improving bus reliability, thereby helping to improve ridership and provide more cost-efficient bus service. The objective of this research is to develop a guide to bus transit service reliability. The guide will include a toolbox of resources that may be used to diagnose and manage bus transit service reliability and will describe benefits, costs, and outcomes of potential policies, strategies, and actions.


  • English


  • Status: Completed
  • Funding: $250000
  • Contract Numbers:

    Project A-42

  • Sponsor Organizations:

    Transit Cooperative Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC    20001

    Federal Transit Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Performing Organizations:

    Parsons Brinckerhoff

  • Principal Investigators:

    Danaher, Alan

  • Start Date: 20160104
  • Expected Completion Date: 20181231
  • Actual Completion Date: 20181231

Subject/Index Terms

Filing Info

  • Accession Number: 01755389
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project A-42
  • Files: TRB, RIP
  • Created Date: Oct 26 2020 8:12PM