What building a model taught me about resilience and building real railways

Author: Aaron Sawyer,
Day: Introduction Day
Session: Modelling and Modernisation

With the growing demand for air travel and the increased traffic through Heathrow's Terminal 5 (T5), it is no surprise the airport is looking to improve capacity and reduce the likelihood of overcrowding. Just as many international airports deploy Automated People Movers (APMs), Heathrow owns and operates Bombardier's APM 200 vehicles, and serve as the main passenger transportation medium between T5A and its sub-terminal stations T5B and T5C. In order to maximise capacity, operational changes were proposed which would see the current shuttle service upgraded to a loop service allowing for the simultaneous running of more vehicles.Whilst upgrading the system to operate in a loop reduces wait times, platform congestion and reliability issues, it also introduces change to the system and the need to create resilience: to inform stakeholders allowing for the successful completion of the operational upgrades; and to ensure the capacity to recover quickly from varying and new operational situations. Within this paper I shall discuss how SNC-Lavalin and Heathrow Airport partnered and through the use a Raspberry Pi, a few Arduinos and other readily available commercial off-the-shelf (COTS) components created an operational N-scale model railway, complete with a fully fledged signalling system, all in aid to assist operational integration and create resilience. The model was designed and coded to closely follow the architecture of the real system; at the heart of the system a Raspberry Pi forms the control centre that hosts separate modules, executing the interlocking, the Regional ATC and the ATO functionality. The trackside components (lineside signals, switches and Hall Effect sensors - to facilitate train detection) are controlled by two Zone Controllers that run on Arduino MEGA microcontrollers which, along with the Vehicle Control Centre, communicate with the control centre via an Ethernet switch at the network layer. Producing the operational model aimed to allow operators to simulate and run a variety of scenarios to test the functionality of the system, especially those relating to degraded modes of operation. However, even prior to the training of operational staff, the model was creating resilience during the delivery of the project. It enabled stakeholders to play-out alternative scenarios, discover and understand the operational upgrade. In addition the model acts as a tool to inspire and fuel the creativity of future engineers. The model's Human Machine Interface features a graphical representation of the system, making it the ideal platform for developing engineers to first try out their signalling routines before trialing them on the real model. I'll close the paper by detailing what building a model has taught me about building real railways, some of which will include:
  • how to increase stakeholder engagement and understanding;
  • greater architectural understanding of signalling systems;•how engineering teachings have changed across generations and how we all can benefit; and
  • how, through the use of COTS components alone, an operationally similar model can be produce to that of a real railway.
Well, with the exception of some very "snazzy" 3D printed Bombardier APM 200 body shells, but you'll have to excuse us for the extra glitz.