Surbiton Station - large gap in the third rail

[Railcar]

While waiting on Platform 1 at Surbiton Station, I noticed there was large gap in the third rail.

It was 65 paces between the places where a shoe would make contact. If we say that my pace is just under a yard, let's say for argument's sake that the gap is 60yards.

Does this prevent, for example, two carriage trains from using Platform 1?

 

[swt_passenger]

Is it definitely both sides of the track? It’s probably the length where the up siding points are (or were) - I’ve not been on the platform there for quite a few years.

 

[Driver2B]

While waiting on Platform 1 at Surbiton Station, I noticed there was large gap in the third rail.

It was 65 paces between the places where a shoe would make contact. If we say that my pace is just under a yard, let's say for argument's sake that the gap is 60yards.

Does this prevent, for example, two carriage trains from using Platform 1?

SWR do not authorise the use of two-carriage electric multiple unit (EMU) trains. Class 456 trains are not authorised to run (outside of depots) as two car trains. Also, no more than one class 456 unit can be included in a formation.

 

[Dr_Paul]

I've noticed this gap too; it's by a trailing point into a short siding. There used to be a conductor rail on the platform side of the line. It was removed some years back. Presumably it was reckoned that there was a somewhat smaller chance of a two-car EMU getting stuck than of someone slipping off the platform and landing on the live rail. I don't think I've ever seen a lone two-car EMU at Surbiton; I'm not sure if the services at Surbiton using two 455s have been beefed up with a 456 as with the Kingston loop and Shepperton services or, if they have, whether the 456 might be uncoupled there.

 

[nlogax]

I've noticed this gap too; it's by a trailing point into a short siding. There used to be a conductor rail on the platform side of the line. It was removed some years back. Presumably it was reckoned that there was a somewhat smaller chance of a two-car EMU getting stuck than of someone slipping off the platform and landing on the live rail. I don't think I've ever seen a lone two-car EMU at Surbiton; I'm not sure if the services at Surbiton using two 455s have been beefed up with a 456 as with the Kingston loop and Shepperton services or, if they have, whether the 456 might be uncoupled there.

Many of those 455 services to Surbs have been beefed up with 456s pretty much since the 456s were reintroduced. They're maintained through to Guildford / Woking or Hampton Court as ten car units, no decoupling as far as I'm aware.

 

[Driver2B]

I've noticed this gap too; it's by a trailing point into a short siding. There used to be a conductor rail on the platform side of the line. It was removed some years back. Presumably it was reckoned that there was a somewhat smaller chance of a two-car EMU getting stuck than of someone slipping off the platform and landing on the live rail. I don't think I've ever seen a lone two-car EMU at Surbiton; I'm not sure if the services at Surbiton using two 455s have been beefed up with a 456 as with the Kingston loop and Shepperton services or, if they have, whether the 456 might be uncoupled there.

Class 456 trains are not authorised to operate as a two-car train on the mainline - they must be coupled with one or two 455 units.

Class 455 and 456 trains cannot be coupled or uncoupled in service.

Many of the services through Surbiton (Woking, Hampton Court and Guildford via Cobham trains) operate as 10-car (455+455+456) but some are 8-car (455+455) and occasionally shorter, especially on weekends.

Most Shepperton services are 707s these days.

 

[Railcar]

Thanks for the information.

A third-rail multiple unit will have shoes on both sides of the carriages that have motors. Are the shoes directly connected together or are they connected via isolating units (even as simple as diodes)?

I had this thought that if they were connected together, someone who was unlucky enough to slip between train and platform at a station might land on a shoe. If the shoes on both sides were connected directly, the person could get a belt even if the conductor rail was on the side furthest from the platform.

 

[swt_passenger]

Thanks for the information.

A third-rail multiple unit will have shoes on both sides of the carriages that have motors. Are the shoes directly connected together or are they connected via isolating units (even as simple as diodes)?

I had this thought that if they were connected together, someone who was unlucky enough to slip between train and platform at a station might land on a shoe. If the shoes on both sides were connected directly, the person could get a belt even if the conductor rail was on the side furthest from the platform.

Yes, all shoes are live, they’re all cross connected on a single unit. They aren’t necessarily just on the coaches with motors either.

 

[Driver2B]

Thanks for the information.

A third-rail multiple unit will have shoes on both sides of the carriages that have motors. Are the shoes directly connected together or are they connected via isolating units (even as simple as diodes)?

I had this thought that if they were connected together, someone who was unlucky enough to slip between train and platform at a station might land on a shoe. If the shoes on both sides were connected directly, the person could get a belt even if the conductor rail was on the side furthest from the platform.

The shoes are not always on the same vehicles as the motors. For example, the 455s consist of DT(A)-MC-NDT-DT(B). The motors are on the motor coach (MC). The collector shoes are on the driving trailers (DT(A) and DT(B)).

All shoes are connected together. Therefore, if any collector shoe of a unit (but not formation) is in contact with the third rail, all other shoes on that unit will be live.

 

[plugwash]

Does any electric-hauled freight run through there? if so do precautions have to be taken to stop the locos getting gapped? (presumablly locos are far more prone to gapping than EMUs)

 

[Driver2B]

Does any electric-hauled freight run through there? if so do precautions have to be taken to stop the locos getting gapped? (presumablly locos are far more prone to gapping than EMUs)

No, all freight through there are diesel hauled.

There might be some measurement trains but they have a 73 on each end.

 

[contrex]

Yes, all shoes are live, they’re all cross connected on a single unit. They aren’t necessarily just on the coaches with motors either.

I used to wonder at how easy it would be to kick a shoe fuse of a SUB or EPB/HAP/CEP etc from a platform. and how I wouldn't like to be in the line of fire if it blew violently.

 

[jopsuk]

Does any electric-hauled freight run through there? if so do precautions have to be taken to stop the locos getting gapped? (presumablly locos are far more prone to gapping than EMUs)

the issue of gapping was the primary reason why class 73 were built with a diesel power unit- the ability to work in unelectrified yards and at engineering works was a secondary benefit.

Regarding connection through the unit- my understanding is that this isn't the case with London Underground stock? And that the Class 313 (at least when operating on the Moorgate line) disconnected the power bus when they switched from AC to DC? Has this been modified with the Southern Coastway fleet?

 

[Dr_Paul]

Class 456 trains are not authorised to operate as a two-car train on the mainline - they must be coupled with one or two 455 units. Class 455 and 456 trains cannot be coupled or uncoupled in service. Many of the services through Surbiton (Woking, Hampton Court and Guildford via Cobham trains) operate as 10-car (455+455+456) but some are 8-car (455+455) and occasionally shorter, especially on weekends. Most Shepperton services are 707s these days.

Does anyone know why 456s aren't allowed to run as single units? Back in old days, there would occasionally be a 2-EPB running by itself on the Windsor lines on a Sunday, and there was also the Wimbledon–West Croydon service, which was always a two-car service.

Is it the case that a 455 cannot be uncoupled from a 456 whilst in service, that is, it is physically impossible to do so; or is it the case they they are not uncoupled for one or another operational reason?

 

[Driver2B]

456s are not authorised as single units due to the risk of getting gapped. However, I don't think that there's much appetite for short two-car units these days.

When 455s and 456s are coupled and uncoupled, a person needs to go between the units, so it is a two-person job. Usually they get coupled and uncoupled at depots, and possibly occasionally at off-peak times at Waterloo. I don't think platform staff (other than at Waterloo) are competent to do this, and it does take slightly longer than coupling and uncoupling some more modern stock.

 

[Snow1964]

There used to be lots of 2car workings. Ascot-Guildford, Lymington branch etc in days of 2HAPs

Before the 10 car suburban scheme, was not uncommon to see an 8car suburban train formed of a 455 plus 2 456s.

 

[swt_passenger]

There used to be lots of 2car workings. Ascot-Guildford, Lymington branch etc in days of 2HAPs

Before the 10 car suburban scheme, was not uncommon to see an 8car suburban train formed of a 455 plus 2 456s.

Also, wasn’t Ascot - Guildford normally pairs of 456s in about 2016/17, it subsequently went back to 450s after the 707s arrived.

 

[norbitonflyer]

The shoes certainly used to be connected through the unit, and must be so in the case of a 456 as it has shoes at both ends but only one power bogie. There was an incident many years ago when passengers were be detrained for some reason between Vauxhall and Waterloo when an alert member of rail staff noticed the compressors starting up on the train and realised the power was back on. What had happened was that another train behind the stranded one had drawn forward to a point where some of its shoes were on the isolated section, whilst others were still on the live section in rear, thus forming a bridge between the live and dead sections.

 

[Dr_Paul]

There was some time back an incident when an EMU -- I can't remember which class -- managed to gap on the long crossing at the town end of the yard at Clapham Junction, blocking the entire yard and several running lines, and causing severe delays on the South-Western lines. It has several slips on it, and only short lengths of conductor rail.