Multiple Signal Failures 07/06/2024

Not sure, but it was even worse earlier in the day with a full line suspension!

Does Wood Lane have to have control of signalling for a service to operate? I recall being in the Earl's Court control room just before the evening peak some 40 years back when there were some blips in the power supply which set off all the alarms in the room, one for each programme machine? Fortunately, the power then cut completely so we were left in darkness and silence. But the trains continued to pass outside. We phoned around and the service was operating as normal from the local programme machines. Of course, to make variations required local intervention in the interlocking machine rooms until Earl's Court power was restored. Could that happen today?

signallers/line controllers need to know where the trains are, they had a loss of train identification/location of trains. I'm no signaller but I believe they need to know where the trains are to keep the service running safely. In consequence, they held the entire service to find where each train is

You can signal the Central Line outside Wood Lane, but it would only be used in emergencies and would require a massive amount of effort and result in a reduced service.

A central control room with radio and a overview diagram showing the position of all trains was part of the original Railway Inspectorate requirements for One Person Operation in deep tubes.

From the sound of it, simply noting occupied blocks via track circuits isn't enough to "know where trains are".
Was the radio system working or out of action?

It really looks like we're back to operational policy, not automatic safety in this case. (If the line doesn't use TBTC or CBTC, they're not relevant to the immediate discussion.)

The Central Line signalling is not TBTC/CBTC, rather a fixed block system by Westinghouse (now Siemens)

I believe the connect radio system was unaffected (as this is separate to the signalling system)

Would it really have been worth trying to run a service especially as drivers would have been told to detrain at the next station?

There seems to be an assumption that the failure was between Wood Lane and the signalling system, and that the signalling system itself was able to carry on running the trains. As far as the information I have to hand appears to be, that wasn't the case at all.

There was an initial failure at Marble Arch then three other locations failed. The failure was a track circuit type failure where the signalling system was indicating the presence of a train but in fact there was no train present. On a non ATO railway this would be akin to a signal remaining at danger because it thinks there's a train in the section.

As a result of the multiple failures, Wood Lane did lose information in terms of train ID's.

Given the nature of the failure, and that multiple locations were involved, the decision was taken to hold the service in platforms and identify the exact location of each train to ensure none were stalled between stations. This then allowed time to investigate and understand the underlying cause of the multiple failures.

Yes it's possible run the Central line's signalling from local control points, but on this occasion that wouldn't have provided a solution to the problem.

There was nothing sinister in the way service control handled the incident - IMO it was handled absolutely correctly.

Wood Lane did a general announcement on Friday, we were told the systems couldn't identify trains, it was showing trains in sections that were empty and sections as empty where there were trains along with multiple track circuit failures.

When I was at Queensway WB they called me on the radio and they thought I was at Lancaster Gate. I think we've only had a failure this bad a couple of times in the last 21 years

Indeed - I thought I provided the wrong information to everyone until I dropped Colin a line saying the information I provided was correct!

A big incident like this will reviewed by the 'higher ups'

And whilst I am not suggesting any member has said this, might I please add that we should not criticise how service control handled this incident, they are all very experienced and training for SC is intense.

How on earth would you get a service going if Wood Lane ordered all trains to hold in platforms whilst they identify train numbers & locations?

They operate the railway in the best interest of the customer (and staff), whilst being as safe as possible. If they want to suspend it, they can! They have been doing this for a long time so it's clear they know what we're doing, most of us wouldn't last a second in the 'hot seat'!

Based on the original 1987 requirements:
Would that apply if the failure was in an open section of line? Not in 1987. It might be considered a requirement if OPO was being proposed as a new concept now.
What about a failure in the double-track sub-surface lines? No, because it wasn't a requirement for Sub-Surface OPO in 1984. There were tunnel sections of the Sub-Surface lines unmonitored from a central control room as late as 2022.

It is perhaps worth considering/remembering the principles behind this - I suggest the underlying requirement is that a system is in place to reasonably quickly notice & react to support a Train OP having problems.
That's probably why twin tunnels or open areas are covered (because other trains could do this) - as Jimbo eludes to.
So local signalman (eg at Edgware Rd) and/or some form of emergency local control with logging of trains between stations/areas may fulfill that - both of course having a facility to communicate with train (eg radio / signal telephone)

I thought they still work, rather they are no longer maintained. Or am I wrong?

This sounds to me as if the system did not fail safe?