Radio Electronic Token Block
Radio Electronic Token Block is a system of
Operation
On arrival at a "token exchange point", the
In the same way as with the traditional system, when a physical token with the name of the section engraved on it would be carried in the cab, the electronic token is received and displayed by name on the train equipment. This token is the authority to occupy the single line, and it cannot be removed from the train until the driver themself releases it. After confirming they have received the correct token, the driver is then given verbal permission to pass the "Stop Board" and enter that section; the stop board is used instead of signals and therefore needs no electrical supply. The fixed distance board on the approach has a single permanent
The simplicity of the lineside infrastructure in RETB areas was reduced by the installation of the Train Protection & Warning System. A train stop loop is provided at each stop board, and is normally activated (so that any train attempting to pass it will be immediately brought to a halt). When the signaller issues a token for a train to enter a section, the TPWS loop at the appropriate board is deactivated, so allowing the train to proceed. Indication of the state of the TPWS is provided by a blue light mounted below the stop board. This shows a steady blue light when the TPWS is activated, and a flashing blue light when it is deactivated.
History
The genesis of the system was on the
With the feasibility of using radio to effect the interlocking of single line token instruments demonstrated, and the additional benefit of voice communication between the signaller and the drivers noted, it was but a short step of invention to moving the instruments from staffed
A new control centre was brought into use at
The future
RETB is being gradually replaced with the new European in-cab signalling system,
From 2014, RETB Next Generation was developed and installed.
RETB Next Generation
Due to the loss of the Band III Sub Band 2 radio frequencies used by the NRN radio system from the digital TV spectrum reallocation the need arose for a system to replace RETB on two lines in Scotland - the West Highland Line and the Far North Line. The rugged terrain and light line traffic made it cost-prohibitive to install GSM-R for these areas and so a new radio system, with new base station and on-train equipment, was developed. This allows RETB to continue to operate on Band III Sub Band 1. RETB NG.[4]
A number of upgrades to RETB NG have been integrated since the system was renewed, to secure its future as an effective signalling and train control system for remote and rural lines around the world. These include improved train positioning technologies that allow train protection without the need for external lineside infrastructure. A 'Request to Stop' system has been installed on the Far North Line, using the RETB radio to alert the driver of passengers on the platform.[5]
References
- ^ The Register of Scottish Signal Boxes, F Alexander & E S Nicoll (1990).
- ^ "ERTMS National implementation plan". Department for Transport. September 2007. Archived from the original (.pdf) on 2008-03-06. Retrieved 2008-03-06.
- ^ "ERTMS Update". rail.co.uk. Retrieved 26 November 2011.
- ^ "RETB - NEXT GENERATION PROJECT". The Rail Engineer. September 2007. Retrieved 2015-07-13.
- ^ "Waving good-bye to hand-signal stops on Far North Line". Network Rail Media Centre. Retrieved 2023-07-10.
- Vanns, Michael A (1997): An Illustrated History of Signalling. Ian Allan Publishing, Shepperton, England.
External links
- Modernisation of the Cambrian Lines; includes discussion on a practical application of RETB.
- Comms Design Ltd - System developer for RETB Next Generation