Three Underground depot derailments during snowfall 11 December

[Taunton]

Didn't seem to get mentioned here but report of three depot derailments last Sunday 11 December

three London Underground trains on three different lines derailed in just 68 minutes due to the exceptionally cold weather which has frozen the capital over the past week. On Sunday (December 11) between 9.42pm and 10.50pm, a Piccadilly line train at Cockfosters, a Central line train at Hainault and a District line train at Upminster all slipped off tracks

MSN

 

[Mojo]

Didn't seem to get mentioned here but report of three depot derailments last Sunday 11 December

Probably because derailments in depots happen fairly often and it isn’t particularly newsworthy.

 

[edwin_m]

Three in one day is exceptional though, but "slipped off tracks" doesn't really make sense. Is there something about cold weather that makes depot derailments more likely?

 

[jnjkerbin]

My guess would be that snow and ice prevented points from fully swinging into position, and that many depots don't have any proving of the position of the points?

 

[Chris M]

"slipped off tracks" doesn't really make sense.

The news report is published by MyLondon, which is generally less reliable than a random bloke down the pub who has been partaking of the establishment's finest ales all day. Indeed they make publications like the Daily Mail and the Sun seem bastions of accuracy by comparison. The author of the story is not a railway journalist, is writing for an audience of random people on social media and likely hasn't even attempted to understand even the very basics of how trains work.

 

[Taunton]

So did the derailments happen, or didn't they?

"Slipped off the tracks" sounds like a typical Underground euphemism, like "Good service" when it isn't. Or how they used to refer to fires on stations as "smoulderings".

 

[bramling]

So did the derailments happen, or didn't they?

"Slipped off the tracks" sounds like a typical Underground euphemism, like "Good service" when it isn't. Or how they used to refer to fires on stations as "smoulderings".

It will almost certainly be on points not quite fully set as a result of ice/snow. It doesn’t need much of a gap between the switch and stock rails for a derailment risk to occur.

Depots don’t have all the safety features which running lines do, hence why they have very low speed limits, generally either 5mph or 10mph.

 

[MisterSheeps]

at the risk of thread drift, is there some feature of hand operated point mechanisms (I believe there are bolting mechanisms for electric points), that notches the lever in the chosen position? or is it only the weight of the lever?

 

[Rogmi]

at the risk of thread drift, is there some feature of hand operated point mechanisms (I believe there are bolting mechanisms for electric points), that notches the lever in the chosen position? or is it only the weight of the lever?

Generally, such as in the Northern line depots before point electrification, the hand worked points are not locked in place. Pulling the lever uses a spring to pull the points over and hold them in place. There is no indication that the points are fully in place, other than by observation. An obstruction at the point tip would prevent the points from fully throwing over. A train going over trailing points set in the wrong direction would just throw them over as the first pair of wheels passed over them. The spring would then hold them in place in the new direction (not that this mattered for trailing points. Effectively, these were spring-toggle points.

See the Point Types book here:

Homea Books

(I've tried attaching the PDF, but don't know if it will work)

 

[Graham S]

at the risk of thread drift, is there some feature of hand operated point mechanisms (I believe there are bolting mechanisms for electric points), that notches the lever in the chosen position? or is it only the weight of the lever?

Handoints are held buy a spring. It is the duty of the person reversing any point to ensure they are full over. Frost and snow make the points heavy or even dry if not greased. So as I say must alway be checked. You will notice most railwaymen after turning a pair of points will put their foot against the blade as a final push/check. Graham.

 

[MisterSheeps]

See the Point Types book here:

interestingly comprehensive reference is that document, thank you

put their foot against the blade

hahaha, i like that, a practical check, thank you

 

[Mawkie]

So did the derailments happen, or didn't they?

The Cockfosters one definitely happened - it was visible to any passenger who cared to look on approach to Cockfosters Station. Not really a big deal tbh.

 

[MaidaVale]

The Cockfosters derailment happened 100%. There were videos of the aftermath floating around staff circles and some stations announced it as the reason for the Picc being suspended between Oakwood and Cockfosters.