Resignalling project counts on specialised cable

Edited by the Engineeringtalk editorial team Nov 22, 2007

Specialised signal cable offers the ideal combination of high performance, long-life, reliability and compact installed dimensions for train axle counter systems.

Nexans has completed a contract for the manufacture and delivery of over 160km of specialised axle counter cable for Balfour Beatty Rail Projects to enable the resignalling of a 29km section of railway track in the Trent Valley, close to Lichfield, Staffordshire.

The resignalling project is a part of a much larger Network Rail scheme known as TV4 (Trent Valley Four Tracking) which will improve the route through Tamworth, Lichfield and Armitage by upgrading and widening the railway from two to four tracks.

"A particular challenge for this project was that the large number of possible variations in the specification of axle counter cables, due to the choice of conductor sises and varying twisted pair counts, means that it is not feasible to deliver from stock", says Steve Robbins, Nexans UK Business Development Manager for Rail Infrastructure.

"So the lead time had to include gearing up the factory in Santander, Spain to manufacture a bespoke order for Balfour Beatty Rail Projects".

"Following the first delivery in May, we then delivered every two weeks, with the final delivery taking place in August".

Nexans axle counter cable is a specialised design of signal cable that offers the ideal combination of high performance, long-life, reliability and compact installed dimensions for train axle counter systems.

Axle counters are track-side devices that monitor and count the number of train wheels passing by them to provide real-time train position information.

The role of the Nexans signal cable is to connect the track-side axle counters, which are usually positioned at intervals of between 1 and 3km, to the central monitoring system.

This very demanding safety-critical application requires a cable that offers a low voltage drop, just a few volts, over long lengths.

This is significantly better than conventional signal cables.

Furthermore, the cable also has to offer a high level of shielding against the electromagnetic interference (EMI) produced by high-voltage overhead catenaries and other power feeds.

In addition to the electrical characteristics, rail infrastructure companies, such as Balfour Beatty Rail Projects, require a fully watertight cable that can offer total reliability over a 20-year service life, as well as being able to resist extreme temperatures, oil and ultraviolet light.

At the same time, the cable has to be compact in size and flexible enough to enable it to fit easily within the already crowded concrete cable ducts.

Out of the total of over 160km of RT/E/PS 00031 axle counter cable supplied by Nexans for the Trent Valley resignalling project, the majority was unarmoured for installation in concrete ducts.

A small length was armoured for use in tail installations where it could not be protected within a duct.