Experience with the Omnilink system in Prince William County, Virginia suggests that with less than 20 passengers per hour, adding 10 minutes of slack time allows accommodation of one or two deviations per hour for routes taking approximately 35 minutes to drive without deviations.
This paper describes a service planning concept based on the existence of a spectrum of possible service designs, ranging from pure fixed route design to pure demand-responsive design with many intermediate options. ITS technologies and scheduling software have matured to the point that it is now realistic to provide and plan transit services in this manner.
Service planners should optimally be able to choose from a list of individual service designs and integrate them into a cohesive overall plan, without concern for software and hardware restrictions. It should also be possible to oversee and manage them all from one control center. Possibilities to consider include using different service designs at different times of day, overlaying more than one design in the same area for all or parts of the day, and making capacity adjustments in accordance with demand. The keys to enabling these possibilities are ITS technologies and scheduling software.
One planning option to consider for demand-responsive services is by time of day. Demand-responsive services are traditionally structured as an entirely separate service organization. Using ITS technologies, these services could be part of a spectrum of service designs under one operating budget. Looking at numerous options, it might be acceptable to somewhat degrade the performance of one service if it is offset by improvement in another. For example, if demand along some fixed routes is below a certain threshold during mid-day or in the evening, switching to Route-Deviation Service may relieve the cost of pure demand-responsive service while providing the additional important benefit of simultaneously mainstreaming some ADA-eligible riders. Experience with the Omnilink system in Prince William County, Virginia suggests that with less than 20 passengers per hour adding 10 minutes of slack time allows accommodation of one or two deviations per hour for routes taking approximately 35 minutes to drive without deviations. (1)
(1) Bruun and Marx 2006 "OmniLink – A Case Study of a Successful Flex-Route Capable ITS Implementation", Transportation Research Record, forthcoming.
Technological Maturity of ITS and Scheduling and Integrated Service Options to Transit Planners
Author: Bruun, Eric C.
Published By: Paper presented at the 86th Transportation Research Board Annual Meeting
Source Date: January 2007
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paratransit, demand-responsive transit