Northern Line CBTC – Loop detection cable

Project: Northern Line CBTC – Loop detection cable

Location: London, United Kingdom

Company: Transport for London / London Underground

Product: RG7M2 0.6/1kV 2.5mm² x one core


Tratos & Transport for London cooperation

Train locations are confirmed at every transition point through a combination of train odometry and accelerometers for accurate positioning data. The transmission from loop to train is an inductive couple of around 56KHz.

The existing XLPE insulated / LSZH loop detection cables, supplied by another manufacturer, were breaking where they were installed with tight bends in station pit sleeper block areas.

The challenge was to design a fully compliant cable to meet all the required electrical, physical and fire safety code of practice demands without changing the copper class 2 conductor construction – with a cable that has very good pliability.

TRATOS proposed the use of elastomeric compounds for the insulation and outer sheath.  TRATOS LSZH’s elastomeric compounds had to comply with LU S1085 A3 (Fire safety materials code of practice) and the operational cable service life of 40 years.

Digital railway

Tratos is pleased to support the digitalisation of London Underground signalling. The railway’s attitude to signalling has changed a lot in the past few decades. In times gone by it was often regarded as something one unfortunately needed to run trains safely. On a modern metro railway, it is now more positively seen as an enabler that helps maximise capacity.

We hear a lot these days about the ‘digital railway’ – which is often taken to mean automated trains. Network Rail and the Secretary of State for Transport miss few opportunities to tell the public that things will be better in future because we will have a digital railway. On Network Rail there is very little to show currently except for a few miles of Thameslink track – although to be fair, what they have got is quite impressive.

Much less talked about is the fact that London Underground have had a digital railway on a number of lines for some time, are busy implementing it on four more lines and are planning to convert the remainder. We might be almost twenty years from a fully digital Underground railway, but there is a detailed plan to do so and much has already been implemented.

The game-changer is undoubtedly Automatic Train Operation (ATO), where the driving of the train is automatic and, nowadays, driven by the signalling system which with an electronic ‘central mind’ that can oversee a route or part of it. Note that this is a considerable advancement on the original Victoria line system, which did little more than automate the existing concept of track speed limits and a restriction on getting too close to the train ahead.

Tratos is long committed to supporting sustainable transport and the UN Global Goals related to the transport, such as Goal 1 End poverty in all its forms everywhere,  Goal 3: Good Health and Well-being,  and Goal 11: Sustainable Cities and Communities.

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