Signalling at Barbican

[SargeNpton]

I'm not that familiar with London Underground signalling, but there is one thing at Barbican that puzzles me.

At the west end of the westbound platform there is a small box in the four-foot that contains two flashing orange lights. These flash whether or not there is a train in the station, and irrespective of the aspect of the normal signals.

Can anyone explain their purpose.

 

[Flange Squeal]

Sounds to me like there might be a temporary speed restriction. I believe drivers have a list of such restrictions in their sign on points (or radio alerts if set up during the day). They then get the flashing lights as a visual warning on the approach, followed by the commencement board (white numbers on blue background). At the end of the restriction, I believe there are then more flashing lights and a board with ‘TT’ on it. Next time you’re there, have a look and see if you can spot a speed or TT board beyond it.

 

[Dstock7080]

indeed, temporary speed restriction.

 

[whoosh]

I'm not 100%, but it sounds like it could be a warning for a temporary speed restriction.

Edit: Beaten to it!

 

[pdeaves]

indeed, temporary speed restriction.

Out of interest, is the speed sign actually tapered, or is this a perspective view? The flashing light drawing above looks like it is viewed from directly in front.

 

[SargeNpton]

Thanks. Though as a temporary speed restriction it had been there for at least 12 months up to March 2020 (haven't travelled on the Underground for six months due to you know what).

Perhaps it's associated with the Crossrail works at Farringdon.

 

[Dstock7080]

Out of interest, is the speed sign actually tapered, or is this a perspective view? The flashing light drawing above looks like it is viewed from directly in front.

The sign isn't tapered, the numerals are elongated though.

 

[bluegoblin7]

Thanks. Though as a temporary speed restriction it had been there for at least 12 months up to March 2020 (haven't travelled on the Underground for six months due to you know what).

Perhaps it's associated with the Crossrail works at Farringdon.

I can’t remember the exact reason, but it was introduced in May 2018 as a temporary measure to sign a new permanent speed restriction (PSR). At the time, CBTC was due for imminent rollout on the section; this makes PSR signage redundant as it is managed by the signalling system.

SMA3 is now due early next year and so the TSR will likely remain in place until then.

 

[SynthD]

The noise from the junction was affecting the locals.