Merseyrail GSM-R ‘leaky feeder’ on track

Date: May 2014

After successfully completing the MerseyRail Grip 4 Design Phase for Network Rail, ADComms were awarded the Grip 5-8 Construction contract.

Mersey Rail tunnel Mersey Rail engineer

The works, scheduled to be completed by June 2014, involve the design and construction of the GSM-R leaky feeder system. The project requires the management of multiple stakeholders to ensure that it fulfils all necessary rail quality and safety standards, delivers on time and costs, but also keeps disruption to Merseyrail services a minimum.

With over 13km of overground and underground wireless infrastructure required, the project requires the management of telecoms infrastructure specialists ADComms. The company employs a small group of experienced contractors that include Linbrooke, the Sheffield-based company that is undertaking the civils installation works.

As the new Merseyrail telecoms infrastructure now enters the final stages, ADComms has begun the testing and commissioning works in preparation for handover to Network Rail’s GSM-R network.

Commenting on the company’s progress, programme manager, Lee Watson, said:

‘This is a fantastic project for ADComms, requiring strong project management, excellent customer communications and robust health and safety standards, in what is a very challenging environment. There are significant RF design and commissioning complexities with the project, and so early on the customer understood the need for this project to be managed by a telecoms specialist. The project demonstrates the depth of radio frequency and fixed telecom engineering capability within the ADComms business.
‘We are extremely proud to be managing this project for Network Rail and are determined to deliver a first-class result on time, on cost and most importantly safely.’

Network Rail project manager, John Kennedy, said:

‘We all knew that the leaky feeder installation was going to be a tough nut to crack in the timescales driven by the programme. It took focused project management from ADComms to ensure a mature and strong collaboration was forged with the Liverpool MDU and Linbrooke, in conjunction with the introduction of some clever mechanical plant.
‘It is particularly satisfying that the Network Rail Life Saving Rules were rigorously applied throughout the delivery, with no recordable accidents.’

Mersey Rail tunnel Mersey Rail engineers

About the project

GSM-Railway is an international wireless communications standard for railway communication and applications.

ADComms’ GSM-R leaky feeder system design accommodates a transparent handover between the Merseyrail tunnel coverage and overground GSM-R coverage. This improved link-up is effective on all routes adjoining the tunnels and the unit complies with EIRENE (European Integrated Radio Enhanced Network) specification.

The new design also makes practical provision for later migration of some of the UHF (ultra high frequency) emergency services, such as the Airwave Emergency services and Mersey Fire and Civil Defence Authority.

The Merseyrail tunnel network is a mixture of single and twin bore tunnels of varying construction, ranging from Victorian brickwork to concrete and steel girders. The clearance in the single and twin tunnels varies greatly between train and tunnel – sometimes by up to a metre.

Construction work within the tunnel complex involves the installation of leaky feeder cables using cable hangers, with the cable acting as an antenna system. Mounted high up on the tunnel wall, the cable is typically supported at around one-metre intervals and stays as close as possible to train-mounted antennas. The placement of the radiating cables within the tunnels, so it follows the design criteria, is critical to system performance.

For the teams required to work at height, for drilling into the concrete and brick, ADComms and its subcontractors utilised road-rail vehicles. The specially-designed vehicles are also used for running the cable off the cable spoolers, which often carry as much as 1,500m.

Due to the cable reel capacities and length of the tunnels, there is often a requirement to join cables of the same type. In some instances this also will be needed to join cables across tunnel sides and over shafts and spaces. When confronted with particularly challenging environments, smaller jumpers can be used.

The cable has to be installed in such a way so as to avoid kinks, dents and gouges, an approach that will help avoid the ingress of moisture – which can oxidise the copper.

All of the work is performed during night time possession and with the high voltage 3rd Rail isolated.

For more information, please contact Lee Watson or Robert Illsley.
Tel:01724 292 200