Approach release at BL1533

[Torfaen]

BL1533 is the third signal westbound from Bristol Parkway, the last one before the junction at Patchway. Line speed is 60 mph, increasing after the junction to 90.

For the past 2 months or so, the signal seems to have been operating with approach control. The route is showing as set on OpenTrainTimes, but the signal is held at red until the train has slowed to 20 or less. There is no TSR signed as far as I can see - and it would anyway seem a bit irregular to slow trains if there was no signage for a restriction.
The only other point of note about this signal is that it's just before an OLE neutral section - not as if that seems in any way relevant.

Does anyone have any ideas what is the reason for the signal operating like this? It's adding at least a minute for everything going westbound, and it's baffling me.

 

[jfollows]

It may be completely different, but Crewe CE154 operated under a Temporary Approach Control Link for some months, https://www.railforums.co.uk/threads/approach-control-signalling-at-crewe.212702/#post-4926511, pending a fix which took some time to implement.
Similar to your case, all trains had to come to a stand even when the route set wouldn’t normally require it.

 

[66701GBRF]

I don't know what the case is here but sometimes when a part of the signalling system can't be relied upon certain restrictions maybe implemented to either not show a certain signal aspect or reduce the chance of a train passing a signal should it revert to red in front of them.

 

[800002]

Do you know if the signal concerned steps up to Green from Red, or to an intermediate Yellow / double Yellow depending on number of aspects available on the signal (i don't know the signal concerned).

 

[SWFreight]

Would be interesting to know. When I have experienced this I assumed it was because a train was routed in front from the Up Bristol, or onto the Down Bristol.

 

[Torfaen]

I'm pretty certain it's a 3 aspect. I am sure it steps up to green because the train accelerates up to line speed when it clears, and I know the next signal is not visible until the train gets quite close.

== Doublepost prevention - post automatically merged: Tuesday at 08:05 ==

I don't know what the case is here but sometimes when a part of the signalling system can't be relied upon certain restrictions maybe implemented to either not show a certain signal aspect or reduce the chance of a train passing a signal should it revert to red in front of them.

That might be a possible explanation. But, if a part of the signalling system is deemed to be unreliable, e.g. a signal could change to red in front of a train, isn't that something that would normally get urgent attention?

 

[800002]

Okay, 2nd follow up:

Is it all / most trains you've been or the same train each day that you experience this with?

If so, which service have you been on?

(There are many possibilities, as being described above, but limited data to interrogate).

== Doublepost prevention - post automatically merged: Tuesday at 08:11 ==

That might be a possible explanation. But, if a part of the signalling system is deemed to be unreliable, e.g. a signal could change to red in front of a train, isn't that something that would normally get urgent attention?

Anything from unreliable track circuit to faulty AWS / TPWS equipment. Although, I wouldn't expect these to endure for very long without being fixed or the route closing.

Im not going to go further, as it won't be helpful.

 

[Torfaen]

Okay, 2nd follow up:

Is it all / most trains you've been or the same train each day that you experience this with?

If so, which service have you been on?

Every train I've taken on that route - since late June, I think. Most often I'm on the 16:37 Cardiff-bound departure from Bristol Parkway, but others I've used have been similarly affected. No idea about freight trains.