Planning a complex infrastructure

Planning the new Infrastructure was a complex task that required taking a number of physical and operational factors into account. First, the Infrastructure had to provide an effective and long term solution to local public transport requirements and support strategies to increase passenger numbers. Second, because the Infrastructure was part of a larger development, space limitations and existing road layouts placed constraints on the design.

The operator needed a flexible solution that would not create any traffic bottlenecks or delays to services. Modelling and simulation was ideal for assessing and understanding such complex interactions in the real world.

Setting priorities

The Infrastructure only exists to enable people to get on or get off metro cars. This means that the main factors affecting the operation of the infrastructure are the times of train arrival and departure and the number of people getting on and off (which dictates the time a train spends at a position). In an ideal world, the operator would be able to dictate the arrival and departure times to help ensure smooth traffic flows and allow the layout of the infrastructure to be optimised.

The designs also had to take account of the passengers´ needs. While trains can set down at any platform they can only load at the platform allocated to that service. This stops passengers having to run between platforms to get their train.

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 Infrastructure, for example, there is a dynamic interaction between the timetable, types of train, routes or services, and physical layout of the Infrastructure. MODELCO 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 Infrastructure, including:

• Timetable details including service number, arrival time, departure time, train loading
• Train details including vehicle types, number of doors, alighting and boarding times
• Service details including, destination, car type and allocated platform.

Key performance indicators

The model was used to assess the operation of the Infrastructure for a number of potential designs with particular attention paid to road layout, number and position of platforms, and how trains would arrive and depart. The operator was able to define a number of key performance indicators (KPIs) to define simulation output data, measuring passengers quality levels or facilities performance reports.

The operator staff could easy change output reports to suit the changing requirements of different services/managers. For example:

• If you are attempting to increase the utilisation of your facilities, you may be most interested in the proportion of the time they spent idle compared to the time they spent busy during a simulated day (or shift).
• If your are concerned to increase the throughput of your operation, you may be most interested in the number of passengers processed during a simulated day´s operation.
• If you are keen to avoid low service levels because your queues are too long, you´ll be interested in the number of passengers on queues and the average queuing times.