Reliability of service

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A common theme among articles within TransitWiki is strategies to improve reliability of transit service (see Off-vehicle fare payment, Transit signal priority, and Internet communications, for example). To understand how to improve reliability of service, transit planners should understand the perception of unreliability among passengers and common responses to such factors. Many people may consider transit were it not for fear of perceived or true unreliability. Reliability can be an objective, performance-based measure, but what is most important for passengers making a decision about how to travel is the subjective perception of reliability [1]. Users do not typically consider the reported statistical performance of a roadway when making a trip; they rely on their personal recollection of typical circumstance or from reputation and other subjective information sources. Therefore, it is in the best interest of transit planners to consider passenger perceptions of the travel experience and, to the extent possible, plan to mitigate factors of unreliability.


In 2013, student researchers from the University of California at Berkeley (UCB) conducted a survey of current and former users of the San Francisco area public transportation system[2]. Survey respondents rated the importance of reliability factors, including the GAP AT A TRANSIT STOP (WHAT IS A GAP) and possibility of waiting for less than 10 minutes for a bus after walking to a stop.

The researchers also gathered information on how passengers handled anticipated unreliability. Real-time information is a tool for mitigating unreliability, for example, but planners should remember that not all riders have access to real-time information. Most important in considering passenger response is that negative experiences can actually reduce transit use by individuals; regaining those lost customers could be more challenging than simply addressing problems of reliability.

Factors of Unreliability

Reliability may seem like an intuitive concept: can I depend on the transit service to be there on schedule and arrive at my destination on time? However there are many other factors that passengers may consider. The availability of seats on a bus, or bike rack space at certain stops could be one factor. For example, passengers have been known to bike to stops earlier on the route if they experience unreliability of rack availability at their preferred stop.

Passenger Behavior in Response to Unreliability


  1. Prashker, J.N. "Direct Analysis of the Perceived Importance of Attributes of Reliability of Travel Modes in Urban Travel." Transportation 8, pp 329-346. 1979.
  2. Carrel, Andre, Anne Halvorsen and Joan Walker. Transportation Research Board: Transit 2013, Volume 2. "Passengers' Perception of and Behavioral Adaptation to Unreliability in Public Transportation." pp 153-162. 2013.