RETB Systems

[Scotrail344Lad]

Is it just the West Highland, Kyle & Far north lines that use it? If there is anymore let me know. Also, how does it actually work? I'm assuming something to do with radio signals being tokens but not 100% sure. Cheers

 

[LowLevel]

Nowadays yes, I believe - the former installations in England and Wales have been removed in favour of other systems, the Cambrian Coast as an ERTMS in cab signalling test bed and the East Suffolk line with modular traditional lineside signals.

 

[edwin_m]

In simple terms:

The route is split up into sections, usually between passing loops. At the start of each section the driver speaks to the signaller, who instructs the computer in the control centre to transmit a digital messsage to the computer on the train. This uses digital coding to make it incredibly unlikely that it can be misread by the systems - a little bit like how a remote car key fob works. The train computer interprets this and displays the limits of the section to the driver, and a separate system on the trackside also sees the message and de-activates a TPWS loop at the entrance to the section.

At the end of the section a similar message is sent in the other direction, which clears the display in the cab and allows the central computer to send out another message when the next train needs to enter the same section.

These radio messages are referred to as electronic tokens, because the way they are sent reflects how physical tokens are handed between the signaller and the driver on older systems.

 

[zwk500]

An excellent overview is available here: https://www.railsigns.uk/info/retb1.html

Worth adding to @edwin_m's summary that the 'tokens' must be exchanged when stationary.

 

[Scotrail344Lad]

Cheers

 

[Lucy1501]

Should it be of any interest, someone did a FOI request for all the RETB regulations in 2023, the files can be found here: https://www.whatdotheyknow.com/request/infomation_about_the_operation_o

 

[Dunfanaghy Roa]

If anyone sees a model layout called 'Roshven' at a model railway show it is based on a branch off the West Highland line and operated by RETB. The verbal messages between driver and control are played, and the 'tokens' displayed on screens. Very well worth a look.
Pat

 

[dk1]

I really missed RETB when it was abolished on the East Suffolk back in 2012.

 

[ainsworth74]

It's now an old video from the late 80s but there's a BR training film on signalling systems which does give an overview of how RETB works which I found interesting (along with the rest of it!). I believe the system has undergone modernisation in the intervening period but broadly operates in the same way as depicted:

 

[Scotrail344Lad]

Thanks all

 

[Belperpete]

There was a proposal to develop a form of enhanced RETB, to give a low-cost signalling system for double lines. I think it was one of the casualties of privatisation.