Multiagent Approach for Public Transit System Based on Flexible Routes

The use of transfers in public transit has the advantages of reducing operational costs and introducing more flexible and efficient route planning. In contrast, the main drawback, from the passenger point of view, is the inconvenience of traveling multilegged trips. To diminish the waiting time caused by transfers, synchronized (timed) timetables were introduced. Their use, however, suffers from uncertainty about the simultaneous arrival of two (or more) vehicles at an existing stop. This can lead to deterioration in system reliability. To alleviate the uncertainty of simultaneous arrivals, a new passenger transfer concept was developed that extends the commonly used single-point encounter (at a single transit stop) to a road-segment encounter (any point along the road segment constituting a possible encounter point). The new concept is based on a multiagent system incorporating new models: (a) simulationbased models that describe the encounter probability of public transit vehicles along a road segment under dependent travel time conditions, (b) an optimization model based on distributed dynamic programming, and (c) a simulation model for the validation of the model. This multiagent concept incorporates a low-complexity, near-optimal model that reduces the average travel time by 7% and increases the number of direct transfers by 285%.