This is the first work we've seen on the ground for the new passing loop at Delmore on the edge of Inverness. Having campaigned for this loop for many years it is wonderful to see real evidence that it's on its way.
Telent, the contractor responsible for the RETB signalling system in use on the Far North and Kyle Lines, was busy in November testing the suitability of the current radio network for the new token exchange point* here.
The RETB system uses a chain of base stations. There are two types of radio used, a Cell Radio talks to the train radios and a Link Radio talks to the adjacent base station (radio mast).
The new token exchange point requires a new base station and it was its planned location that was under test.
The work needed at Delmore also gives the opportunity to build more Radio Network Resilience into the RETB network. More will be required of the RETB system once the loop is installed as the points at each end will be motorised and radio controlled. An important decision made by the Far North Line Review Team was that the train operated points on the line, which have a speed restriction of 15 mph, would be replaced, allowing 45 mph entrance and exit to loops.
One lane of the A862 was occupied by Telent's equipment for the duration of the tests. The project involved setting up a temporary mast using an aerial attached to the jib of a crane, wired into a test vehicle. Once this was set up a Train Radio coverage test run was carried out between Inverness and Muir of Ord by one of the line's Class 158 trains, with radio signal testing equipment in the rear cab to measure the new proposed radio links to the adjacent base stations.
*all single line railways are divided into sections, each of which must only carry one train at a time. A unique 'token' exists for each section and it is held by the train occupying that section. Under RETB the token is electronic and is issued to the driver by radio at the token exchange point to allow it to proceed into the next section. It is relinquished at the end of the section and exchanged for the next section's token.