Should the responsibility for warning about speed restrictions ahead be separated from the system which warns that there is another train ahead?

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Should the responsibility for warning about speed restrictions ahead be separated from the system which warns that there is another train ahead?

mugam4 said:

Should the responsibility for warning about speed restrictions ahead be separated from the system which warns that there is another train ahead?

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The driver got no separate warning about speed restrictions only those associated with the aspects displayed. There is a deeper issue though of using the signalling to control train speed by using restrictive signal aspects and drivers becoming conditioned to always seeing a clear aspect at the next signal and thus getting into a routine.

Nicholas Lewis said:

The driver got no separate warning about speed restrictions only those associated with the aspects displayed. There is a deeper issue though of using the signalling to control train speed by using restrictive signal aspects and drivers becoming conditioned to always seeing a clear aspect at the next signal and thus getting into a routine.

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Sorry, but what relevance do speed restrictions have to this incident?

Haywain said:

Sorry, but what relevance do speed restrictions have to this incident?

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He means the approach control to the crossover - there may well be some learnings about approach control and the potential dual implication of a single yellow clearing onto a fast line which introduces a layer of risk.

Haywain said:

Sorry, but what relevance do speed restrictions have to this incident?

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The previous poster had asked if they got a warning for a speed restriction which applies to the Up Slow to Up Fast crossing move.

Nicholas Lewis said:

The previous poster had asked if they got a warning for a speed restriction which applies to the Up Slow to Up Fast crossing move.

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That's route knowledge, isn't it?

Haywain said:

That's route knowledge, isn't it?

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It's also part of the rationale for Approach Control being fitted to signals protecting diverging routes with significantly lower speed limits.

If the signals were strictly related to aspect sequence and a separate (likely ATP) system governed speed then the risk of mistaking the meaning of the signal aspect would have been lower.

mugam4 said:

Should the responsibility for warning about speed restrictions ahead be separated from the system which warns that there is another train ahead?

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As it happens, ETCS will go the other way - the signalling system will calculate the speed curve and enforce it on the driver as an integrated part of the Movement Authority.

zwk500 said:

It's also part of the rationale for Approach Control being fitted to signals protecting diverging routes with significantly lower speed limits.

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In this case the approach was to 50 mph crossovers, and from what we already know it doesn't appear that they were taken excessively fast. Line speed on the up slow is 90 mph, but the driver of the 360 wouldn't be expecting to take the up slow beyond WH356/Bedford South Junction anyway.

Unlike the incidents at Spital (? near Peterborough) and Grantham, the 'normal' and slower route was being taken this time, so the expectation should have tied in with what the signalling was telling the driver.

Was an opportunity missed at the signal protecting the crossover to warn the driver of the true obstruction ahead due to the signal being approach controlled, or is that information we do not know yet?

mugam4 said:

Was an opportunity missed at the signal protecting the crossover to warn the driver of the true obstruction ahead due to the signal being approach controlled, or is that information we do not know yet?

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That will depend on the configuration of the approach control. I don't know if WH356 would normally 'step up' if the Up Fast was clear. We shall have to wait for the RAIB report.

zwk500 said:

That will depend on the configuration of the approach control. I don't know if WH356 would normally 'step up' if the Up Fast was clear. We shall have to wait for the RAIB report.

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If normally going up fast from WH356 and the Up fast is clear , then it goes Y and as you get close to it it flashes through YY to green .

baz962 said:

If normally going up fast from WH356 and the Up fast is clear , then it goes Y and as you get close to it it flashes through YY to green .

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So are you saying if WH154 is red (protecting 1B76) this will not happen? In which case the lack of this YY - G sequence at WH356 was an the unusual indication.

baz962 said:

If normally going up fast from WH356 and the Up fast is clear , then it goes Y and as you get close to it it flashes through YY to green .

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Presumably though you get the horn before the train strikes in the approach track circuit that releases the signal to show the highest aspect level possible. So your used to getting the horn cancelling it then a clear aspect so you manage the speed across the crossover then accelerate when train is clear of jcn. Its c 900m from the trailing crossover down to WH154 so a number of seconds would have elapsed before the train past over the 152's AWS inductor. What the train saw at this point will be key and lets hope the OTMDR is intact and can provide that answer.

zwk500 said:

That will depend on the configuration of the approach control. I don't know if WH356 would normally 'step up' if the Up Fast was clear. We shall have to wait for the RAIB report.

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I believe the signal would normally step up. However, it would be fairly common for a driver to encounter restrictive aspects due to the likelihood of having to wait for a train passing on the up fast, so having a yellow aspect remain yellow at the junction signal wouldn’t be unusual. Whilst this wouldn’t happen every time, it’s certainly something that would arise from time to time. I think it’s reasonable to say that it would be very rare for the passing train to then come to a stand having come past at full speed, so causing a driver to encounter the next signal remain at danger.

Very common situation for error, unfortunately. Routine situation where a cautionary situation is routinely experienced. Contributory sequence of events in so many incidents. Some may disagree with this, however I feel this was also a factor at Salisbury, however this is my personal opinion and not necessarily what the RAIB concluded (or were able to prove, which isn’t quite the same thing).

Having said all this, I’d still have expected the driver to react to WH154’s red aspect, even if too late. It’s much more unusual for a driver to drive on through a red signal. Hence I suspect there is bit more to this, whatever that may be.