Tourists flock to Scotland every year, drawn by the rugged scenery. Many travel by rail, on the West Highland lines to Oban, Fort William and Mallaig and the Far North lines to Kyle of Lochalsh and Wick/Thurso.

However, the spectacular countryside, the mountains and moorlands of the landscape, while they may attract visitors and sightseers, they also present a major challenge to those who have to design and construct the railway’s communications network.

The system in place is known as the Radio Electronic Token Block (RETB). It comprises the radio system, the signalling Solid State Interlocking (SSI) and equipment located on-board trains. It is a ‘Class B’ system under the Control Command and Signalling sub-system technical specification for interoperability (TSI).

The RETB Next Generation Project, described in issue 125 (March 2015), is more than a renewal of the current system, as it also mitigated the risk of radio interference when European frequencies for digital television changed in December 2015. This meant that the existing ‘Band III sub-band 2’ radio equipment had to be replaced with new radio equipment operating on ‘Band III sub-band 1’. The project’s remit also involved the development of replacement on-train, depot, engineering and trackside equipment.

Hilltop delivery

Fenix Signalling, in collaboration with Telent, has successfully delivered the Train Protection Warning System (TPWS) signalling testing works on the West Highland Line, the first part of the RETB Next Generation project.

RETB is an electronic development of the physical token system for controlling traffic on single lines, with the driver receiving movement authority via a cab display radio (CDR). Fenix Signalling is responsible for the signalling design and the signalling testing and commissioning works for the project under the management of Eddie Murphy, Fenix head of projects.

The project, commissioned by Network Rail and led by Telent as principal contractor, has seen remote hilltop base-stations upgraded to support the new frequency. Access has been problematic, and has even involved the use of helicopters to deliver equipment where there were no suitable roads or tracks. Using this method, Telent’s on-site operations team, led by senior operations manager Lee Clinton, has installed radio equipment at the highest site on Network Rail infrastructure – White Corries in the GlenCoe ski resort.

In addition, new on-train, depot and transportable maintenance equipment has been developed by Comms Design Limited and installed by Telent field engineers.

Phase One complete

Prior to commissioning all sites, two TPWS trial sites were selected at Crianlarich and Spean Bridge, with two-week trial periods being conducted at each site. The success of the trial sites has resulted in the Fenix and Telent teams completing the works at 19 sites on the West Highland Line, covering more than 150 miles of track. This included modifications to the TPWS power supplies and commissioning of the TPWS frequency converters to support the frequency change. All this was accomplished despite some extreme weather courtesy of Storm Douglas.

The commissioning of the West Highland Line TPWS marks the completion of the first phase of TPWS testing and commissioning as part of this major project. Phase two will see the TPWS on the Far North Line commissioned. This includes a total of 19 sites from Inverness out to the Kyle of Lochalsh in the West, and up to Thurso and Wick in the North, covering in excess of 200 miles of track.

This year will also see the next phase – the split of the Far North interlocking at Inverness SCC, with Fenix Signalling responsible for principal testing and the commissioning of the new SSI at Inverness.