- In Customer Stories
- Posted 08/01/2003
South Yorkshire Passenger Transport Executive (SYPTE) uses WITNESS simulation software from the Lanner Group to finalise its plans for the new Doncaster Interchange
The new Doncaster Interchange is designed to replace two existing bus stations serving the town centre. It is funded by a combination of PFI and regeneration investment as part of a development to revitalise the town centre with new amenities and shopping areas.
Planning a Complex Interchange
Planning the new Interchange was a complex task that required taking a number of physical and operational factors into account. First, the Interchange had to provide an effective and long term solution to local public transport requirements and support strategies to increase passenger numbers. Second, because the Interchange was part of a larger development, space limitations and existing road layouts placed constraints on the design.
Finally, the Interchange had to accommodate the needs of the private sector operators that have operated the bus network since public transport deregulation a decade ago. SYPTE needed a flexible solution that would not create any traffic bottlenecks or delays to services.
“Modelling and simulation is ideal for assessing and understanding such complex interactions in the real world,” says Peter Elliott. “We chose WITNESS because the company demonstrated similar applications in transport and other industries.”
The Interchange only exists to enable people to get on or get off buses in Doncaster town centre. This means that the main factors affecting the operation of the Interchange are the times of bus arrival and departure and the number of people getting on and off (which dictates the time a bus spends at a position). In an ideal world, SYPTE would be able to dictate the arrival and departure times to help ensure smooth traffic flows and allow the layout of the Interchange to be optimised. But timetables are decided by the individual operators, and adherence to them is affected by congestion. This limits SYPTE's control over arrival times.
The designs also had to take account of the passengers' needs. While buses can set down at any stand they can only load at the stand allocated to that service. This stops passengers having to run between stands to get their bus but also prevents buses being allocated to stands dynamically.
Real Information Makes Model
WITNESS is a highly configurable business modelling and simulation tool designed to provide a visual interpretation of complex processes. The most successful models are based on high quality information that can be used to create the simulated “real world” representation. At the Interchange, for example, there is a dynamic interaction between the timetable, types of bus, routes or services, and physical layout of the interchange. Peter Elliott and his colleagues used information from a variety of sources to devise a simulation model that took into account all of the potential factors affecting the operation of the Interchange, including:
- timetable details including service number, arrival time, departure time, bus loading
- bus details including vehicle types, number of doors, alighting and boarding times
- service details including operator, destination, vehicle type, allocated stand, entry and exit points
- interchange details including road lengths, stand positions, travel speeds, traffic light cycles
Key Performance Indicators
The model was used to assess the operation of the Interchange for a number of potential designs with particular attention paid to road layout, number and position of stands, and how buses would arrive and depart. SYPTE was able to define a number of key performance indicators (KPIs) that helped identify which layout would provide the best service to customers while also accommodating the requirements of operators. These KPIs included:
- bus lateness, showing how many buses would leave their stands late, compared
- with the published timetable, for a given layout when other factors such as late arrival had been included
- percentage of buses getting on stand first time
- recirculation efficiency, a measure of how much a bus drives round looking for a vacant stand
- time spent at the Interchange
- percentage of time at Interchange spent on stand
Simulation proved to SYPTE that the Interchange could work with the 30 stands allowed for in its original proposal. This was important because some operators had been sceptical about the original plans and were only convinced of the feasibility once they had seen the simulation in action. The simulation also provided SYPTE with information about every bus using the Interchange, which was used in negotiations with operators. Information on passenger and pedestrian flows was used by architects and engineers to finalise the design of walkways and other facilities.