First Great Western

First Great Western sought a real-time system for advising train drivers of the best approach to meeting the timetable in the most energy efficient manner, reducing wasted fuel considerably. First Group started with trials on Hull Trains in 2009, followed by HSTs on Great Western. TTG won a competitive tender, and fleet fitment of 180s and HSTs was completed in 2011. The system is intended to support drivers in achieving more consistent timetable compliance by advising the driver of the optimum speed, typically less than line speed, required to reach the next timing point at the right time. It advises whether to coast or accelerate through information provided in the cab based on track geometry and speed profile, timetable, train’s characteristics and train position information.

In the first two years of operation, First Great Western HSTs reduced CO2 emissions by 7,500 tonnes and NOx emissions by 2,600 tonnes. Other franchises followed with fleet fitments. A further benefit is that drivers see fewer restrictive aspects at signals, since they approach at the planned time, rather than early. They also get advanced notice of approaching speed restrictions, reducing brake wear and tear.

A Standalone DAS (S-DAS) advises drivers using a static timetable, manually loaded in advance, and so is unaware of subsequent changes. Further evolved systems that can take changes into account are Networked DAS (N-DAS) and Connected DAS (C-DAS).

N-DAS uses mobile networks (e.g. 4G) to manually send changes, but like S-DAS, these systems cannot consider the impact of other trains. On a busy and congested network, such as in Great Britain, this limits the benefits that can be obtained. C-DAS takes data from Traffic Management (TM) systems and automatically sends changes in real-time to the DAS system onboard the train. TM systems have visibility of all train movements through a given area and apply predictive logic to the underlying data to recommend changes that will result in optimising the combined performance of all the trains.

A more limited form of C-DAS can use national customer information systems as the source of changes. This facilitates real-time updates to individual trains but will not optimise overall area performance.

In the UK, communications between TM systems and other rail business systems are facilitated by the National Layered Information Exchange (LINX) system, which standardises data flows. For this reason, UK C-DAS should use LINX as a standard interface to receive the latest information rather than directly from TM systems, as these will operate differently region by region depending on the supplier of the TM system. This also requires that TM systems publish all changes to LINX.