Flexible transportation services

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Flexible public transportation services is a general term describing a range of strategies typically utilized in local public bus transportation. It is commonly applied to services which incorporate elements of, but are not exclusively fixed-route or demand-responsive models. Compared to those standard models, in some cases flexible services may be more cost-effective, efficient, serve a more broad range of users, or some combination of each. Flexible services may be more common in rural or suburban areas than dense urban areas but examples are found even up to areas with a population of several million.

Example benefits include cost savings in small urban areas when serving persons with disabilities rather than a strictly demand-response service. First-time public transit users may be encouraged to use a flexible service in suburban communities to connect with regional options. Flexible services such as fixed-route deviation can improve reliability for customers who would otherwise be dependent on an exclusively demand-response system. Agencies may find that a flexible service is a more effective use of resources compared to traditional models [1].

Although flexible transportation services can be beneficial, like any service they can suffer from problems. Difficulties with scheduling around demand (difficult to keep time at high demand, for example), generating ridership, and confusion among consumers have been cited as reasons for discontinuing flexible services. In at least one instance, a flexible service was replaced by a fixed-route service when ridership increased enough to justify the change [2].

Defining Flexible Public Transportation Service

Flexible public transportation services can be used in addition to an established service or as a replacement for one. Often a flexible model is used to gain efficiency over a more rigid service type. In some cases the flexible model can provide options for a wider base of users than fixed-route service. Flexible services typically carry only a few passengers per trip, generally more than demand-responsive systems but fewer than would typically be required to justify a fixed-route.

Agencies should be aware of certain trade-offs in using a flexible service in place of other, traditional types. Flexible services may be more expensive to operate per-trip than fixed-route, although savings can be realized when combining fixed-route and paratransit. Operators should recognize that flexible services tend to be more similar in approach, expense, and expectation to demand-response than fixed-route. The support of more robust technology for communications, scheduling, and dispatch may be required when compared to traditional models. This could increase the start-up cost of a flexible service over other types. Agencies should consider each strategy to establish which seems most appropriate to meet set goals.

Core Strategies

There are six different approaches to flexible public transportation services, ranging in nature from nearly fixed-route to nearly demand-responsive. The structure of flexible public transportation is dependent on the characteristics of the area served, varying between rural, small urban, and large urban regions.

  1. Route Deviation: a defined path and schedule is used to define a service area, but the vehicle(s) may serve requests for pick-up or drop-off within a specified zone around the path. The deviation-zone may or may not be strictly bounded. According to a survey of service operators, the deviation is commonly between one-half and three-quarters of a mile from the route. Three-quarters of a mile from is the distance mandated by the Americans with Disabilities Act (ADA) for paratransit service complementing a fixed-route service. This service type is most effective in areas with enough density to support a predictable route and schedule but could benefit from the flexibility of serving origins and destinations that are otherwise off-route.
  2. Point Deviation: service is provided within a defined zone with a set of specific stops, but the path between the stops is unspecified and the vehicle will serve locations within the zone on request. Point Deviation can be most effective in an area with specific trip destinations but dispersed origins, or vice-versa.
  3. Demand-Responsive Connector: service operates entirely by demand-response, but includes scheduled transfer points connecting with a fixed route. The Connector is an effective option when there are scattered origins but a common destination once connected with the fixed-route system.
  4. Request Stops: a scheduled, fixed-route service in which certain stops are served only in response to passenger requests. Generally the vehicle must deviate off the fixed path to serve request stops. This is similar to route deviation, but limited only to specific stops instead of a range of unspecified locations within a zone.
  5. Flexible-Route Segments: a portion of an otherwise scheduled fixed-route is operated as demand-response. Assigning a segment of a fixed-route to flexible service can be beneficial in very low-density areas.
  6. Zone Route: a primarily demand-response service that has set departure and arrival times at its end points. The Zone Route is effective when there is not a defined corridor to travel, but specific a specific origin or destination exists within an area.

According to research undertaken by the Transit Cooperative Research Program (TCRP), route deviation is the most commonly operated flexible service type. This is followed by the use of request stops and the demand-responsive connector.

Common Characteristics

Most agencies charge the same fare on a flexible route as on the fixed or demand-responsive service. Some agencies charge a different fare for flex-service, more often higher than lower.

Agencies primarily provide special training for area-famliarization with regards to flexible services. Some agencies also use mobile data terminals or maps, which require additional skills training.

A core element of flexible public transportation services is a communication plan. A system may include how and when passengers communicate requests for service, whether requests can be negotiated, how drivers are dispatched, and whether other agencies participate in provision of service. A wide variety of options for requesting service are utilized, with some agencies requiring reservations while others allow nearly on-demand service. Dispatching requests to the driver is largely done through two-way radio, although some agencies use cell phones or mobile data terminals. Agencies may also employ automated vehicle location (AVL) as a tool for both operation and consumer information.

Examples of Flexible Service in California

  • Omnitrans, serving the San Bernardino Valley region, is cited as a participant in the study which supports TCRP Report 140 [3]. Omnitrans utilizes both Zone Routes and a Demand-Responsive Connector under the brand OmniLink to make connections to its fixed-route system.
  • The San Joaquin Regional Transit District (RTD), serving California’s Central Valley provides the Hopper Service, which reallocated existing resources to create a deviated-fixed route. This combined both fixed-route and complementary paratransit services to enhance customer satisfaction and improve cost-effectiveness.


  1. "'Hopper' Deviated Fixed-Route Service". Presentation at APTA Bus & Paratransit Conference. 2012.
  2. Transit Cooperative Research Program. "A Guide for Planning and Operating Flexible Public Transportation Services." 2010.
  3. Transit Cooperative Research Program. "A Guide for Planning and Operating Flexible Public Transportation Services." 2010. Page 82.