Many-to-many demand responsive transportation systems consist of vehicles which take passengers from their origins to their destinations within a service area. In dial-a-vehicle systems, in order to circumvent the undesirable feature of taxicab systems, vehicles are allowed to deviate from their direct route to serve other passengers and the emphasis is on building efficient tours to increase vehicle productivity. This strategy increases riding times but also increases average occupancy and productivity of the vehicles, and hence decreases average waiting times. A similar problem is faced by the recently developed `webvan' food delivery service which takes orders for groceries over the Internet and commits to delivery to the order's home (or specified address) within a given time frame. The difference is there is a single origin for a defined market area but multiple destinations. It is possible to organise dial-a-transit system in a similar manner but it is not clear how this form of delivery configuration would impact the productive use of the vehicles, drivers and other factors used. The interest we have in this area is to develop a model that can be used to assess the improvement in productive efficiency or of consumer welfare with the use of ITS applications, such as AVL in providing this service. AVL provides information to both the service provider and the service consumer. The information on the supplier side allows the dispatcher to allocate vehicles ti achieve some objective. In most cases this has been defined to minimise costs or maximise productivity. We find this to be a narrow definition, after all this is a service industry and meeting the needs of customers should be the objective. This can be defined as maximising consumer welfare or utility. Perhaps a more reasonable objective and one that recognises the scarce resource issue is to have an objective of maximising welfare which means the sum of consumer and producer surplus. Such an objective function recognises the separate roles of customers and suppliers and the trade-off of increasing costs and increasing quality. Using this approach we should be able to say something about optimal market size, vehicles per market and optimal vehicle size. (Author/publisher)
Samenvatting