SIGNALLING & TELECOMS
other systems currently in use.
“We demonstrated that we could work with another supplier’s groundside equipment [Ansaldo-STS in the case of the Cambrian], which is going to be imperative going forward when you have a multi-supplier procurement process between groundside and on-board equipment,” he said.
Tomlin added that Network Rail could actually see first-hand that the Hitachi system was working, interfacing correctly and was compatible to the European specifications on interoperability. “It was an absolutely key trial for us.”
Benefits
Compared to traditional signalling systems, ETCS brings the signalling into the driver’s cab, so it is a fully automatic train protected (ATP) system.
Conventional ATP transmits permitted speed information to the on-board device via analogue signal sent from the ground equipment. In digital ATP,
the ground equipment
sends stopping point information by radio signals.
“With ETCS, if you have all trains fitted on the line you can actually remove conventional signals and put up block marker boards (signposts, effectively) by the side of
ETCS Levels
The ERTMS/ETCS application “levels” define different uses of ERTMS as a train control system, ranging from track to train communications to continuous communications between the train and the radio block centre.
• ETCS Level 1: Is designed as an add-on to or overlays a conventional line already equipped with line side signals and train detectors. Communication between the tracks and the train is ensured by dedicated balises located on the trackside adjacent to the lineside signals at required intervals, and connected to the train control centre. Receiving the movement authority through Eurobalises, the ETCS onboard equipment automatically calculates the maximum speed of the train and the next braking point if needed, taking into account the train braking characteristics and the track description data. This information is displayed to the driver through a dedicated screen in the cabin. The speed of the train is continuously supervised by the ETCS onboard equipment.
• ETCS Level 2: As opposed to level 1, level 2 does not require lineside signals. The movement authority is communicated directly from a Radio Block Centre (RBC) to the onboard unit using GSMR. The balises are only used to transmit 'fix messages' such as location, gradient, speed limit, etc. A continuous stream of data informs the driver of line-specific data and signals status on the route ahead, allowing the train to reach its maximum or optimal speed but still maintaining a safe braking distance factor.
• ETCS Level 3: Still in its conceptual phase, allows for the introduction of a moving block technology. Under ERTMS level 1 and 2, movement authorities are determined using fixed blocks - sections of tracks between two fixed points which cannot be used by two trains at the same time. With ERTMS level 3, accurate and continuous position data is supplied to the control centre directly by the train, rather than by track based detection equipment. As the train continuously monitors its own position, there is no need for fixed blocks – rather the train itself will be considered as a moving block.
Source: The European Rail Traffic Management System – Factsheet rail technology magazine Aug/Sep 14 | 85
the track, which is exactly what the Cambrian Line has done in Wales,” said Tomlin.
Those markers tell the driver
where the train
must come to a stand when a ‘stop’ indication is shown on the DMI (drive machine interface), known as a ‘closed’ block marker. When the DMI indicates a movement authority past a block marker, that marker is ‘open’ (more detail on how trains’ positions are detected in the box out).
© Halász István ETCS Levels
Tomlin said reducing the amount of lineside infrastructure brings “huge benefits” in terms of safety and maintenance reduction for Network Rail and the wider industry.
Additionally, the ETCS mode is said to be much more efficient than the current system. “The fact that the driver has got all the information provided to him dynamically in his cab on a screen is a huge benefit and it is something that has been delivered in Europe for the last 10 to 15 years,” said Tomlin.
huge amount of experience already out there and the UK is now ramping up its national programme to bring in those benefits and efficiencies.”
There are different levels of ETCS (see box out), which is one of the main components of ERTMS, along with the mobile communications standard (GSM-R) and traffic management.
Network Rail has established a programme to roll out ETCS Level 2 GSM-R (Global System for Mobile Communications – Railway). Tomlin said: “ETCS Level 1 is a discrete balise intermittent ATP system but it is something that we’re not going to go for in the UK, so Level 2 is the way forward.”
“There’s a
He added that Level 3 is effectively a moving block system, again using the radio system but with an increased reduction of trackside infrastructure so “you’d actually remove your track circuits and fully remove your signals”.
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