Dynamic Ridesharing services can run the gamut of technical complexity from manually operated call centers to fully automated, Internet-based ridematch applications, and from personal automobiles to fully automated personal rapid transit (PRT). In its ultimate form, Dynamic Rideshare is essenitally a low-cost paratransit service that provides a means by which two or more travelers can be joined in real time with others headed to, or past, the same locale with taxi-like responsiveness.
The main purpose of dynamic ridesharing is to reduce the number of single occupant vehicle trips by providing an individual the opportunity to join with another person or persons in a car or vanpool for a particular day or trip. An individual submits their request for a trip to the operations center or central database of the program by telephone, email, or the Internet. A request may be made for any destination or time of day, but matches are more likely to be found for travel in the peak periods and in principal commute directions.
The ridematching software searches its database of trip requests and returns potential trip matches to the requestor based on the closest match of time and destination. Contact information is provided and the requestor must then contact the potential trip provider(s) to make arrangement for the trip. Dynamic ridesharing benefits both drivers and passengers. Passengers benefit by having an alternative when their usual mode of travel is unavailable. Drivers benefit by either having someone to share the cost of the trip or by qualifying to use high occupancy vehicle (HOV) lanes to reduce the travel time of the trip. The most common forms of ridesharing are subscription ridematch and shared paratransit services using private carpools, private or corporate vanpools, or government-funded paratransit vehicles.
Subscription ridematch services are administered by hundreds of public and private Transportation Management Associations (TMAs) throughout the U.S., as well as by many state DOTs. Subscription ridematch services allows travelers to register themselves as passengers, drivers, or both, and the match prospective drivers and passengers having common travel times, preferences, origins, and destinations. Most sponsored ridematch services also offer a guaranteed ride home in case of emergencies.
Shared paratransit services are typically operated by government entities (either in-house or through a contracted provider) that provide curbside pickup for multiple riders on preplanned routes that are "dynamically" programmed the day before. This type of next-day rideshare has found widespread use in satisfying the transportation needs of state and federal welfare, Head Start, disabled, and special needs programs throughout the U.S.
Personal Rapid Transit (PRT) and Autonomous Dial a Ride Transit (ADART) are future technological versions of dynamic ridesharing. Development projects are underway, but no fully functional and operational examples in revenue servcie exist in the U.S. yet.