The following is a guest article by Peri Smith.
The London Underground network is an area understood by few outside the realms of railway engineering. For this reason, this article sets out to provide an insight into significant technological railway development that has occurred.
As an end user of the railway system, that is, as a passenger, you are probably only and primarily concerned about getting to your destination in a safe and efficient manner. However, for this efficiency to be realised and often unbeknown to most, the railway has a complex web of technology and people that provide a supporting backbone.
It would be interesting to know how many people thought about the complexities of the railway. For example, do you ever think about how signals work? How passenger information is displayed? How passenger flow is determined within a station or even how platform edge doors operate? For those that do, this is encouraging and for those that are keen to learn more I hope you find this article of interest.
Metro lines across London are transforming, the Jubilee Line is an example of this. The Jubilee line has seen significant change and is an interesting case explored here. However, before delving into the detail, it is important to understand the constituent parts that make a railway system.
As shown below, trains do not operate in isolation there is a network of interfacing operational, control and technical subsystems. Systems have dependencies on one another and enable railway operation with important input from the human interface be it the driver, signaller or controller.
The application of Seltrac which started in Toronto is an exciting technology which later spread throughout the world later to be implemented here in the UK. It benefits lie in its ability to meet a number of desirable objectives, such as enhanced train operation, improved efficiency and service recovery. It achieves this through the concept of moving block. The principle behind moving block is to achieve safe train separation whilst achieving increased line capacity where more trains can operate. In order for this to occur dynamic calculation of train separation based on train location, maximum operating speeds and braking is required. This results in reduced train separation distance, reduced trackside equipment/ associated costs and increased train occupancies in the same area. All factors desirable to the passenger on their daily commute.
The Seltrac signalling system also changes the driving environment, the driver is now no longer predominantly focusing on signals but utilises a driving interface designed to display to the driver accurate details of speed, location and speed restrictions
This new user interface replaces the old speedometer, research and development of this environment had to ensure that a number of variables were not impacted. Such as readability in varying light conditions, clear information display, correct pitching of audible alerts and clear colour coded display to prioritise urgency. The driver’s environment has thus undergone change with a change to the ergonomics.
The examples presented here are merely an introduction to some of the metros subsystems and the considerations that need to be accounted for during design to enable successful implementation of a modernised product into a legacy railway network steeped in heritage.
I hope this article has stoked some interest into the field of railway engineering, however no matter how advanced the design and technology the primary design focus is for a safe railway through automation.