Shortlands possible signal problem sighted

Todya while waiting for the 15:49 train to Orpington, the signal at the end of platform 2 was displaying yellow (on down relief line), and while looking towards it (and Bromley South), noticed it change to double yellow, then a second later go back to yellow again. Why might this have happened?

The signal stayed yellow for at least 5 mins, (red guards Bromley South in this case) and when the train arrived and progressed to Bromley South, did so as normal but the driver went slowly till a green before the station showed.

My first thought was the bulb went on the second yellow light, which if true would have been a very rare catch. Given the signal beyond was green by the time my train got there suggests no train was held at Bromley South, and if there was the signal should not have tried to go double yellow. There are no junctions enabling crossover between main and relief lines between the Shortlands and Bickley platforms, the crossovers being either side.

Any thoughts?

The most likely cause would be the signaller setting the route, then cancelling it.

Why? I don't know! If the top yellow was out, then the driver would most certainly of reported it as that (depending on the area) would of been an irregular sequence.

Looking at Realtime Trains for Bromley South at that time, the sequence of arrivals at platform 3 is down Sevenoaks, up Victoria, down Orpington (your train.) The signals are most likely semi automatic, so would clear following the Sevenoaks, then be set back protecting platform three and the down to up crossover to route the up train into the platform. Hence your train approaches Bromley South under caution until the up train is clear of the crossover and the down route can be set. The interlocking would prevent any conflicting route being set if your train was approaching Bromley. All routine and perfectly normal.

Emblematic said:

Looking at Realtime Trains for Bromley South at that time, the sequence of arrivals at platform 3 is down Sevenoaks, up Victoria, down Orpington (your train.) The signals are most likely semi automatic, so would clear following the Sevenoaks, then be set back protecting platform three and the down to up crossover to route the up train into the platform. Hence your train approaches Bromley South under caution until the up train is clear of the crossover and the down route can be set. The interlocking would prevent any conflicting route being set if your train was approaching Bromley. All routine and perfectly normal.

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Interesting, was platform 2 at Bromley South closed yesterday? It normally gets at least 6 trains an hour - Victoria to Orpington and Thameslink to Sevenoaks.

bromleyboy21 said:

Interesting, was platform 2 at Bromley South closed yesterday? It normally gets at least 6 trains an hour - Victoria to Orpington and Thameslink to Sevenoaks.

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It certainly looks that way. Could have been any of a number of things, planned or otherwise, between Bickley Jn. and Shortlands Jn.

Seriously - anythng untoward should be reported - once spotted an irregularity with a blank aspect at Blackfriars (no red - after a train departure !) - spoke to station staff who did not understand the issue as the "non red" cleared to a single yellow. Luckily a driver on the platfrom overheard the conversation , next train arrived - I and driver spoke to the other driver. Signalman at VS put the road back - "no red !" ......suitable process followed and I got a thank you letter from the station manager saying that the non driver staff member had been "retrained" - and to personally speak to him if anything like that happened again. Found an irregularity at Bridgend some years later - which again was followed through commendably - and yes , there was a glitch in the interlocking / route tables.