Dynamic rescheduling
Description/Objective
Dynamic Rescheduling is a facility within a CAD/AVM system that allows the schedule to be adjusted in real time or semi-real time in response to prevailing circumstances.
Dynamic rescheduling can operate at various levels of complexity, including the following situations:
- Smoothing the schedule or headway pattern when a vehicle is missing
- Recalculating the schedule or headway pattern when one or more additional vehicles are operated on a route (e.g. in response to unusually high demand)
- Recalculating the schedule and intermediate times when a route diversion takes place
- Recalculating the schedule based on the actual overall or sectional running times
- Creating an alternative schedule in case of serious disruption
In some cases, following the dynamic rescheduling process, the revised schedule is transmitted to the in-vehicle devices and to the real-time travellers information channels. This ensures that the information channels can provide a reasonably accurate level of information to travellers. This is particularly important if the route or list/sequence of stops is adjusted.
Technologies, data and resources
Dynamic Rescheduling is a software application, performed on the CAD/AVM server. Depending on the complexity of the rescheduling to be performed, it may require substantial computing power. Following the dynamic rescheduling process, revised or temporary data files may be transmitted to in-vehicle devices and to the traveller information channels.
Depending on the rescheduling to be preformed, it utilises some or all of the following data sources:
- The specified service reference data – routes, timetables, total and sectional running times
- Revised routings, diversions, road/link closures, and their applicable times/dates
- Revised total and/or sectional running times
- Rules and constraints (e.g. availability of spare vehicles and crews) for the dynamic rescheduling
- Current vehicle location and status
Advantages and Cautions
The primary advantages of Dynamic Rescheduling modules are to:
- adapt to prevailing circumstances and disruption
- apply consistent logic and processes, and minimise discretionary/arbitrary response strategies by dispatchers
- communicate the revised schedule to in-vehicle devices and traveller information channels
The principal cautions in relation to Dynamic Rescheduling are:
- despite the interest in Dynamic Rescheduling for over two decades, the number of practical applications are relatively few
- complex calculations, potentially requiring extensive data and significant computing power
- limited opportunities to test/validate the revised schedule before deployment
Relevant Case Studies
Florence