RETB Renewal

Work has started to renew the Radio Electronic Token Block (RETB) on the Far North and Kyle Lines. This has become urgent as there is to be a reallocation of the radio spectrum nationally as a result of the introduction of 3G and 4G telephones and the existing licences for the various radio systems used on National Rail will be withdrawn after December, 2015; the new system is planned to have a lifespan of twenty years. In some ways, this is a disappointment to us as we would have preferred to see "real" signals installed, at least at the southern end of the route where we understand there is already a cable route. Site surveys started last summer and will continue until March this year. Following on from that, installation of base stations, radio masts and antennae will begin, along with new equipment in Inverness signalling centre and on the trains. Although the new radio control system is essentially a "like-for-like" replacement, there will be some changes to the method of control of the line. Currently, there are two RETB control desks at Inverness: one deals with the signalling and the other with the level crossings. Under the new arrangements, each of the two desks will deal with all aspects of its own geographical area. One of these will be Inverness to Kyle along with, possibly, part of the FNL north of Dingwall; the other will be from a point yet to be decided to Thurso and Wick. This is like the arrangements on the West Highland Lines - which are undergoing similar changes to their RETB - where one desk deals with Craigendoran Junction to Oban and the other with Crianlarich to Mallaig, except for the area around Fort William which is conventionally signalled. Currently, only one train at a time can be given RETB instructions throughout the whole of the Far North and Kyle Lines; in future, one per section will be possible. We have also been told that the new arrangements will make it easier to alter or add infrastructure, such as new or altered passing loops, new Token Exchange Points and new freight sidings, etc.. It would be nice to think that this could be tested in the near future. However, there would still be the cost of trackwork to be added into any upgrade of the infrastructure.