Level crossing on the Central Line....shock! (pun intended)

[JamesPB]

How did that work in practice then? No live rail for the width of the crossing perhaps? With the short two-car train coasting for a few seconds across the 5 or 6 metres?

What he's on about you ask.
Well this morning while randomly flicking through the 2006 second edition of "The Central Line" by messrs. Bruce & Croom, I came across a late 50s early 60s picture of a red 1935 tube stock two-car train (Central Line) which worked as a shuttle at North Weald, out on the eastern edge of the Central Line, and part of the accompanying text reads: "...A level crossing just north of the station remained in use until the line's closure in 1994"

The line in question being the Epping-Ongar section.

BUT does this scenario scare the life out of anyone else the way it did me?

A level crossing on a track-source electric system!!!

Unfortunately the relevant chapter doesn't explain how this curiosity actually worked.

[bramleyman]

Despite living in Essex and not too far away from there, this is the very first I have heard about it, so will keep an eye for further information.

[swisstrains]

Am I missing something here James?
Why should the third/fourth rail electrical system used on the Underground create any more problems at level crossings than the third rail system used by Network Rail?

[JamesPB]

First of all I didn't realise that any of the mainline railways had track-source power. I thought all mainline electircs in the UK were the same as in sweden i.e. overhead cables connecting to pantagraphs.

If that is not the case, is the network rail system the same as the Underground's?

The 3rd rail on underground lines is very live! As a police officer in Central London I saw the ghastly evidence of this on a regular basis. And which is why all central London police officers know how to turn the power off before getting on to the track or going into tunnels. So a live rail on a level crossing is a recipe for disaster surely. Unless of course something about the track at this level crossing was different.

Which is why I've never seen or heard of a level crossing on the Underground until I read of this one.

Hence my query.

[boilersuit]

Hi James. The trains on the Underground system have pick-up shoes at both ends and also on some of the intermediate cars, so a short gap in the live rail is not a problem; if one shoe loses contact there are always others to continue feeding the motors with current without any interruption. This is how they manage to continue running over points, crossings etc.

[swisstrains]

Originally Posted by JamesPB

First of all I didn't realise that any of the mainline railways had track-source power. I thought all mainline electircs in the UK were the same as in sweden i.e. overhead cables connecting to pantagraphs.

If that is not the case, is the network rail system the same as the Underground's?............................

James,
Many Network Rail lines in London and the South-East and on Merseyside use a system where power is collected from a live third rail. The return current then passes via the normal running rails and some of it leaks into the ground. The London Underground system is very similar but uses a live third and fourth rail. Having the fourth rail means that the normal running rails do not have to be used for the return current so preventing most of the leakage to earth. Current leaking to earth on Underground lines built inside cast iron tunnels causes corrosion so must be avoided.
As Boilersuit says, all trains have more than one set of current collector shoes so gaps in the live rails at level crossings and pointwork do not pose a problem. As you pointed out in your initial post, level crossings are rare on the surface lines of the London Underground system but they are very common on the third rail lines operated by Network Rail.

[richard thompson]

If they hadn`t got a method of managing gaps in the live rail ( more than one pick up)trains wouldn`t be able to change direction at points.
Richard

[JamesPB]

Thanks chaps!

[Sprocket]

The Bessbrook and Newry tramway in Ireland (1880s or so until the 1940s) had 3rd rail (central) power, except where it crossed a road junction at an oblique angle. This was far longer than the tramcars, so they had bow- collector pickup just for this stretch.

The Southern Railway also had some 3rd rail locos which had pantograph pickups for use in goods sidings, where it would obviously be undesirable to use 3rd rail where shunters were manually coupling wagons using a pole.

[Flying Pig]

Originally Posted by richard thompson

If they hadn`t got a method of managing gaps in the live rail ( more than one pick up)trains wouldn`t be able to change direction at points.

This actually raises a very important issue. As a rule of thumb most third rail EMUs have pick up shoe at 'each corner', ie one on each side of the leading bogie and final bogie (with various exceptions - particularly on newer stock).

There are of course thousands and thousands of gaps in the conductor rail, and these are mostly configured so as NOT to be exactly 4 cars apart. This is particularly important for the normal stopping places such as stations, but there are locations where stopping at a signal can cause the train to become 'gapped'.

Local instructions or Company Instructions to drivers advise of this. One such place is on the Metropolitan Spur in London. Drivers of (4 Car) trains which are stopped on a red signal in the Down direction at the bottom of the slope are advised not to move off if it clears to only a single yellow. They should should only move if they receive two yellows or a green. This is because stopping at the next signal places them in the middle of Metropolitan jn which is full of gaps, and if they do become stuck they will block all trains out of Charing Cross !

Another issue raised earlier in this thread is third rail in sidings and depots. This is another place which is extremely gappy and when you motor through the points at a depot the Line Light clicks on and off all the time. It's extremely easy to gap in a depot, and is an unannounced cause of many cancelled peak trains !

The advice to a driver of a gapped train is to 'Gravitate'. Which is a posh way of saying release the brakes and hope to hell that there's enough of a gradient for the train to roll gently back onto the conductor. I can promise that If that does happen you feel like Christmas has come early.

Regards

FP