Irregular token working - Incident at Aylesbury

The RAIB has recently reported on an incident at Aylesbury, where two trains (one carrying passengers) occupied the single line section between Aylesbury and Claydon at the same time. Fortunately the trains came to a stop in sight of each other before a collision occured. It is a salutary reminder of the dangers of slack working with tokens, especially in circumstances as here, where there is an intermediate (auxiliary) token instrument. The main cause was that the token for a freight locomotive was returned to the intermediate token instrument while the locomotive was still standing in section on the running line. There are other important lessons to be learnt from this incident that may well be of relevance to token operation on Heritage lines.

<http://www.raib.gov.uk/cms_resources/080611_R132008_Aylesbury.pdf>

David

 

I shudder to think what the outcome may have been. Thanks for sharing it with us

 

I am supriesed that - given the incredibly (fail)safe nature of single line operation this has happened not once but 4 times. Recomendations in the report suggest improvements in training and written/verbal communication but not an upgrade to the infrastructure - I would have thought appropriate.

 

Thanks for posting that David, it was very interesting. You could see what was going to happen as you read the report and it highlights the importance of the driver keeping hold of the single line token when on a single line. It is luck in this instance that the line speed was low and the weather was clear and bright.

It is interesting that the two token release plungers allow a token withdrawal from any of the machines, it appears to allow for a bit of a lottery if someone were waiting at each machine. 8-[

 

I think the idea is that you have to have verbal permission as well before removing the token.

The NYMR chaps might know more about this type of system, the Middlesbro-Whitby line using remote release token machines between Battersby and Whitby, the one at Grosmont being a subisduary in the middle of the Glaisdale Whitby section.

 

Indeed you should have verbal permission before removing a token at a remote token instrument and I'm sure the NYMR guys follow the correct procedure.

At the risk of being wrong, isn't there two machines at Whitby; one on the platform and one near the run round siding?

 

Intermediate token machines were reasonably common. The nearest to me having been the section between Corfe Castle and Worgret Junction (pre-closure) where Furzebrook sidings were operated in this way. The system is only failsafe until someone puts a token back when there is still a train in the single-line section - an elementary mistake, but too often forgotten by some goods guards in more modern times. There was an incident at Honeyborne some years ago when a guard put part of the train in the sidings and returned the token to the machine with the rest left on the main - a following HST being halted as it entered the single line (after the goods train-crew realised their mistake and contacted the signalman) - a very near miss. Less lucky was a Class 33 driver who was killed when he hit part of a train was left on the Up line at Holton Heath (near Wareham), the Ground Frame release given back to the signalman and his light engine allowed into the section (albeit in a double track situation).

All systems are only failsafe as far as they are correctly operated.

 

The token instruments on the Whitby -Battersby line are not remote release. Whilst the regulations require you to ask permission from the signalman before removing a token he does not give a 'release'. There is nothing other than procedure that prevents anybody from extracting a token if they have the appropriate key to the instrument cubicle and no other token is already out. The regulations require drivers to obtain permission to withdraw a token, inform the signalman that they have done so and then request permisssion to pass the stop board (in effect the section signal). When the train is out of section, the driver has to inform the signalman that the complete train is out of section, any ground frame is restored to normal and that the token has been replaced in the instrument. All these conversations are recorded.