Transit Dependence

Transit dependence (also known as transit captivity) refers to individuals or markets that rely on transit for most or all of their travel needs. This is usually discussed in contrast to “choice” users who have access to a private vehicle but choose to use transit. An individual is considered transit dependent if he or she has no driver's license or lives in a household without a private vehicle.

Transit captivity is also discussed at the market or neighborhood level, where demographic factors such as age, disability, or low income are identified as indicators for transit dependence. In the United States, about 30 percent of the population 5 years of age and older is considered transit dependent.

Transit captivity is an important concept in transit planning and modeling, because captive markets account for around 70 percent of transit trips in the United States. They are seen by transit agencies as a secure market because it is assumed that captive users who have no other transportation options will always use transit. Although this may be the case in the short term, if the captive market is neglected, the long-term effect could be users changing their behavior, such as by purchasing an automobile, changing home location, or forgoing trips.

Transit agencies tend to focus on attracting “choice,” or discretionary, riders, because it is assumed that those users will only select transit if it is superior to the car in regard to cost, time, and/or convenience. Discretionary users are more likely to change their transit use in response to changes in fare, travel time, and reliability than captive users.

The proportion of transit-dependent travelers using a system depends on the transit mode and network coverage. Captive riders tend to dominate in low-quality, infrequent, and dispersed networks typified by local bus systems. In contrast, high-frequency, radial commuter-oriented networks, typified by light and heavy rail, tend to attract a larger proportion of choice riders. This is because [Page 1434]efficient, radial rail networks are more likely to be a competitive alternative to private motor vehicle travel and therefore attract choice riders. In contrast, local bus systems are usually uncompetitive compared to private cars and are more likely to be used by transit-dependent populations that have few travel options.

In much of the United States, transit-dependent households face a transportation environment particularly unsuited to their situation. Rapid decentralization of housing and jobs has dispersed travel destinations in a way that puts many locations out of reach of public transportation. Transit-dependent households generally have poorer access to jobs, education, and other important destinations than households with access to a car.

In American cities, transit-dependent households can access only 40 percent of metropolitan jobs within 90 minutes of travel on transit. Low-income job seekers are more likely to find work if they have access to a car than if they are reliant on public transport. Studies in the United Kingdom have found that many job seekers, especially young adults, cite a lack of personal transport as a significant barrier to finding work. People without a car are much more likely to miss medical appointments, have difficulty accessing grocery stores, and may forgo social activities because of their lack of transport options.

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