Turnback sidings

[Derekstuart]

On 08/01/2022 at 11:55, HillsideDepot said:

A fascinating variation on the theme, albeit with one very long platform along side the turnback sidings, was Bournemouth. A TC and REP combination would arrive from London. A class 33/1 came from turnback siding on to the front and took the TC on to Weymouth. The REP cars then go to turnback sidings before going to the up platform shortly before the next TC & 33/1 arrive from Weymouth. The TC couples to REP, the 33/1 uncouples and runs to the siding while the train continues to London. Repeat all day!  

Seen here in later days when class 73s replaced the REP power cars which were donating their motors to the Wessex Electrics then in build.

 

 

It sounds like the 73 at the end is running on diesel, which seems strange. It is possible for the diesel engine on a 73 to be running when using the third rail, although it's doing nothing except wasting fuel. It's clearly drawing power from the third rail as you can see the sparks. I really can't think of any reason for it.

 

Derek

[DY444]

On 12/01/2022 at 20:15, Derekstuart said:

 

It sounds like the 73 at the end is running on diesel, which seems strange. It is possible for the diesel engine on a 73 to be running when using the third rail, although it's doing nothing except wasting fuel. It's clearly drawing power from the third rail as you can see the sparks. I really can't think of any reason for it.

 

Derek

 

The clip doesn't show the train starting to move; we only see it when it is already moving.  If you look at that pointwork you can see there is barely a coach length of conductor rail in front of the train before a substantial gap towards the up line.  If the ED had entered that gap under power then it would have drawn a huge arc off the rear shoe given the low speed and consequent high motor current so I imagine drivers would have considered it wise to shut off before that gap but given the short distance the train would be moving very slowly.  Maybe the ED did draw a large arc which messed up the video and explains why the train's initial movement is not seen? 

 

Anyway it seems to me there are two possibilities here.  Either the engine was started as a precaution in case that long gap caused a problem, or, the initial movement of the train (which we don't see) was on diesel because of the gap and the shoes were then lowered at about the same time as the clip started ready for when the ED reached the next bit of conductor rail.  Having said that it makes more sense (to me anyway) for the change back to electric to have been done whilst running along the platform or better still when the train had stopped at the platform! 

 

Bottom line is we'll never know!

Edited January 14, 2022 by DY444

[bécasse]

The use of EDs on the Gatwick Express from 1984 quickly showed up a potential for the shoe arcing to start fires including one serious one (at Battersea Park IIRC). It was quite a surprise to discover one morning that the whole Gatwick Express service was being worked by 4-CEPs in jaffa cake livery! EDs quickly returned to the service but worked in pairs on diesel power until flash guards could be fitted around the pick-up gear.

 

I don't know whether an instruction was given to use diesel power elsewhere in areas with complex pointwork but even if it wasn't, the word would quickly have spread among drivers that the practice was an advisable precaution.

 

Although the diesel engine in an ED was only rated at 600hp they were surprisingly effective on diesel power. I once travelled from Brighton to Victoria in a very well loaded 8-CIG rake behind a single ED on an occasion when the juice was off and it made excellent progress - although there was no hotel power to the carriages, of course.

[big jim]

Wembley stadium on the chiltern line has a turn back siding between the up and down lines for trains exiting the country end of wembley depot wanting to head back into london, also used by terminating Marylebone-wembley passenger shuttles on wembley event/Match days 

[Pandora]

Herne Hill station, there was the long siding as named in  the sectional appendix, disused overgrown and rust, with the Blackfriars work around 10 to 15 years ago,the siding changed direction to face Loughborough Junction, a new crossover and signals  installed on the Holborns, and the  long siding became the turnback siding

[Oldddudders]

1 hour ago, big jim said:

Wembley stadium on the chiltern line has a turn back siding between the up and down lines for trains exiting the country end of wembley depot wanting to head back into london, also used by terminating Marylebone-wembley passenger shuttles on wembley event/Match days 

I believe in days of yore there was a full balloon loop around the old stadium to allow trains to head straight back towards London. Presumably that is long gone. 

[Oldddudders]

1 hour ago, bécasse said:

The use of EDs on the Gatwick Express from 1984 quickly showed up a potential for the shoe arcing to start fires including one serious one (at Battersea Park IIRC). It was quite a surprise to discover one morning that the whole Gatwick Express service was being worked by 4-CEPs in jaffa cake livery! EDs quickly returned to the service but worked in pairs on diesel power until flash guards could be fitted around the pick-up gear.

I think the complex pointwork and inevitable brief gappings in Vic station throat led to problems with aircon units sulking on the sets, too. 

[Pandora]

On 08/01/2022 at 11:01, The Pilotman said:

I recently came across a picture on here taken at West Worthing where there appears to be a turnback siding between the up and down lines used by terminating services. Until I saw this picture, I was only aware of such a siding at Bedwyn on the Berks & Hants route; the limit of the “suburban” service from London/Reading/Newbury.

Are there any other examples of such sidings just beyond a station where services terminate but the main line continues? I’m thinking particularly of British main line practice (ie. not the London Underground etc.) in the last fifty years but I don’t mean bay platforms where some trains terminate at larger through stations. 

Sidcup Station,  the  siding on the down line has lighting,  a walking route and  access stairs for crews,  the main use is for when the Dartford loop is under possession,  a shuttle service to and from London operates, the siding and associated crossing permit the start and end of the working

[Fat Controller]

55 minutes ago, Oldddudders said:

I believe in days of yore there was a full balloon loop around the old stadium to allow trains to head straight back towards London. Presumably that is long gone. 

I thought the balloon was intended to return trains northwards?

Just seen the map that Mike posted; my apologies for my incorrect post

Edited January 14, 2022 by Fat Controller
Correcting my previous, erroneous, post.

[The Stationmaster]

48 minutes ago, Oldddudders said:

I believe in days of yore there was a full balloon loop around the old stadium to allow trains to head straight back towards London. Presumably that is long gone. 

There was indeed - installed for the Empire Exhibition in 1924 and remained in use until, I think, the early 1960s.  

 

https://en.wikipedia.org/wiki/Wembley_Exhibition_railway_station#/media/File:Wembly_Park_map_1938.jpg

[Nick C]

3 hours ago, Oldddudders said:

I think the complex pointwork and inevitable brief gappings in Vic station throat led to problems with aircon units sulking on the sets, too. 

I thought they still had shoes on the GLVs in order to help with that? Internet suggests they still had the motor bogie as well, which I didn't know - I'm guessing there was no traction power connection through to the 73...

[big jim]

3 hours ago, Oldddudders said:

I believe in days of yore there was a full balloon loop around the old stadium to allow trains to head straight back towards London. Presumably that is long gone. 

very much so, I did walk it during a PNB at Wembley depot back in about 2011 and out pics in my then ‘in work with chiltern’ thread of the remains of it, in the intervening 11 years the trackbed has further disappeared under more buildings and development

[jim.snowdon]

3 hours ago, Nick C said:

I thought they still had shoes on the GLVs in order to help with that? Internet suggests they still had the motor bogie as well, which I didn't know - I'm guessing there was no traction power connection through to the 73...

My understanding is that the GLV retained its traction equipment and was operated in multiple with the 73s, for which purpose the Mk2 trailer sets were equipped with standard SR 27-way jumper cables and EP brakes.

 

[keefer]

Correct, high-level control and brake connections but no power jumper so ED and GLV each under their own power.

[Tom Burnham]

20 hours ago, Pandora said:

Sidcup Station,  the  siding on the down line has lighting,  a walking route and  access stairs for crews,  the main use is for when the Dartford loop is under possession,  a shuttle service to and from London operates, the siding and associated crossing permit the start and end of the working

This was originally installed when trains started terminating at Sidcup regularly - 1967 timetable as I recall. Started as  loop and only later became a dead end siding. In about 1973 down trains in the morning were running out of course and the train after my regular one actually turned up first. I got in it, but was annoyed to find it held in the loop while the following train overtook it, to get back to the right order...

[caradoc]

Some in Scotland:

 

Ardrossan South Beach

Cumbernauld

Dalmuir

Exhibition Centre (where the Siding is alongside the platforms so trains actually terminate and start at Anderston)

Newton

 

[Oldddudders]

4 hours ago, Tom Burnham said:

This was originally installed when trains started terminating at Sidcup regularly - 1967 timetable as I recall. Started as  loop and only later became a dead end siding. In about 1973 down trains in the morning were running out of course and the train after my regular one actually turned up first. I got in it, but was annoyed to find it held in the loop while the following train overtook it, to get back to the right order...

I think you are right. The evening service a few years later certainly had an all-stations CX to Sidcup and bounceback, closely followed by a through service to Gillingham, fast from London Bridge to Sidcup. 

[DY444]

On 14/01/2022 at 10:13, bécasse said:

The use of EDs on the Gatwick Express from 1984 quickly showed up a potential for the shoe arcing to start fires including one serious one (at Battersea Park IIRC). It was quite a surprise to discover one morning that the whole Gatwick Express service was being worked by 4-CEPs in jaffa cake livery! EDs quickly returned to the service but worked in pairs on diesel power until flash guards could be fitted around the pick-up gear.

 

The arc guards were the visible sign of the modification but the major change was to force the camshaft to run all the way back before the locomotive would take power again.  This was only a problem when the locomotive was trailing and the driver thus has no idea what the state of the camshaft is as it is being run up and down automatically in response to the position of the standard SR EP 4 position power controller in the driving vehicle. 

 

The surprising thing is that this issue never manifested itself before given the widespread use of 73s in PP mode on the Bournemouth line in the early days.  It just so happens that Battersea Pier Junction uniquely presented the proverbial alignment of the holes in the Swiss cheese to expose the problem.  

 

On 14/01/2022 at 11:49, Oldddudders said:

I think the complex pointwork and inevitable brief gappings in Vic station throat led to problems with aircon units sulking on the sets, too. 

 

On 14/01/2022 at 15:15, Nick C said:

I thought they still had shoes on the GLVs in order to help with that? Internet suggests they still had the motor bogie as well, which I didn't know - I'm guessing there was no traction power connection through to the 73...

 

On 14/01/2022 at 18:42, jim.snowdon said:

My understanding is that the GLV retained its traction equipment and was operated in multiple with the 73s, for which purpose the Mk2 trailer sets were equipped with standard SR 27-way jumper cables and EP brakes.

 

 

On 14/01/2022 at 19:44, keefer said:

Correct, high-level control and brake connections but no power jumper so ED and GLV each under their own power.

 

The GLV provided the (eth) supply to power the MA sets on the coaches, which thus cut in and out as the GLV traversed conductor rail gaps.

Edited January 16, 2022 by DY444

[jim.snowdon]

14 hours ago, DY444 said:

The arc guards were the visible sign of the modification but the major change was to force the camshaft to run all the way back before the locomotive would take power again.  This was only a problem when the locomotive was trailing and the driver thus has no idea what the state of the camshaft is as it is being run up and down automatically in response to the position of the standard SR EP 4 position power controller in the driving vehicle. 

On any emu the driver has no knowledge of the position of the camshaft, other than the traction equipment not having advanced beyond series or parallel. The equipment looks after itself whenever a conductor rail gap is encountered, but does have a finite response time, which is why there are long standing (and now largely obsolete) standards for the minimum duration of gapping. They are there to give the equipment time to drop out and run back to the start. They don't apply to electric locomotives, the principle being that the driver, being on the locomotive, can judge when to shut off. That principle can't apply when the locomotive is at the other end of the train, and locomotives, having a very short shoe span compared to multiple units, are particularly susceptible to gapping.

 

Their short shoe span also makes then susceptible to drawing substantial arcs between the last shoe and the (departing) conductor rail ramp as they become gapped. Combine that with low speed and there is a distinct risk that the arc will transfer to either the axleboxes or bogie frame, or to the running rail, particularly if the train is on a diverging route through pointwork and the shoe from which the arc has been struck is passing over the stock rail.

 

[Derekstuart]

On 14/01/2022 at 08:09, DY444 said:

 

The clip doesn't show the train starting to move; we only see it when it is already moving.  If you look at that pointwork you can see there is barely a coach length of conductor rail in front of the train before a substantial gap towards the up line.  If the ED had entered that gap under power then it would have drawn a huge arc off the rear shoe given the low speed and consequent high motor current so I imagine drivers would have considered it wise to shut off before that gap but given the short distance the train would be moving very slowly.  Maybe the ED did draw a large arc which messed up the video and explains why the train's initial movement is not seen? 

 

Anyway it seems to me there are two possibilities here.  Either the engine was started as a precaution in case that long gap caused a problem, or, the initial movement of the train (which we don't see) was on diesel because of the gap and the shoes were then lowered at about the same time as the clip started ready for when the ED reached the next bit of conductor rail.  Having said that it makes more sense (to me anyway) for the change back to electric to have been done whilst running along the platform or better still when the train had stopped at the platform! 

 

Bottom line is we'll never know!

I'm not sure I understand. It came out of a dead end siding- which is electrified. Granted, that is a reasonable length without a third rail, but by the time it got there it was running fast enough for momentum to carry it over. Again I'm not sure what you mean by the arc messing up the video.

 

If I understand correctly, the diesel engine can be idling ready for use, but as soon as it is selected for traction, the circuit breakers cut in immediately on the shoe gear and thus if there is no circuit then there is no current being drawn and so no spark so clearly it wasn't running on diesel when crossing over.

 

No, we won't know- not unless someone who knows what they are talking about happens to read my question and offers a response; asking questions in the hope of finding someone more knowledgeable about the subject is one of the great things about RMW.

Apologies to the topic starter for the off topic question.
Derek

[DY444]

2 hours ago, Derekstuart said:

I'm not sure I understand. It came out of a dead end siding- which is electrified. Granted, that is a reasonable length without a third rail, but by the time it got there it was running fast enough for momentum to carry it over. Again I'm not sure what you mean by the arc messing up the video.

 

If I understand correctly, the diesel engine can be idling ready for use, but as soon as it is selected for traction, the circuit breakers cut in immediately on the shoe gear and thus if there is no circuit then there is no current being drawn and so no spark so clearly it wasn't running on diesel when crossing over.

 

No, we won't know- not unless someone who knows what they are talking about happens to read my question and offers a response; asking questions in the hope of finding someone more knowledgeable about the subject is one of the great things about RMW.

Apologies to the topic starter for the off topic question.
Derek

 

Firstly let's establish that we're talking about the same thing.  I'm referring to the train leaving Middle Siding 1 at about 10:40 on the video.

 

"It came out of a dead end siding- which is electrified. Granted, that is a reasonable length without a third rail, but by the time it got there it was running fast enough for momentum to carry it over"

Yes but when crossing from No1 siding to the up line there is a conductor rail gap about two coach lengths long.  This gap is about a coach length ahead of where the ED was when stationary.  If the ED started on electric then either the driver would be notching up manually or would have placed the electric controller in Series Run Up.  The former would assist with preventing a huge arc at the gap but speed would be very low by the time the gap was reached; the latter would have produced a higher speed but there would be less margin for error in shutting the electric controller in time to prevent an arc.

 

"I'm not sure what you mean by the arc messing up the video"

The clip does not show the train starting from rest.  The first time we see it in motion the ED is on the aforementioned conductor rail gap.  Why did the clip not show the train starting to move?  I have no idea but was speculating that an arc *might* be one explanation.  If you point a video camera at an electric arc you can get quite a big area of white out as the intense light from the arc saturates the internal gubbins of the camera. *If* the ED did start on electric and there was an arc drawn, that arc *could* have messed up a part of the footage when the train first starts moving.  I'm not saying that did happen, merely suggesting it *might* have. 

 

"If I understand correctly, the diesel engine can be idling ready for use, but as soon as it is selected for traction, the circuit breakers cut in immediately on the shoe gear and thus if there is no circuit then there is no current being drawn and so no spark so clearly it wasn't running on diesel when crossing over".

Yes the engine can be running when on electric.  The shoes are raised when the diesel controller is moved away from lock off.  My point is that as the video doesn't show the train starting to move or the point when the ED enters the first conductor rail gap, we can't tell whether the initial movement is on diesel or electric.  We don't know if there was an exhaust plume when power was applied and we don't know if there was an arc struck by the ED.  All we know is that the shoes were definitely down when the ED reached the end of that gap and that electric power was applied at some point as the ED and REP motor coach both subsequently struck arcs.

 

I think it's safe to say that the engine was started for a reason.  My assertion is that the most likely is to ensure it was readily available in case the gap caused a problem, or to initially start the train mindful of said gap.  Given the sequence of events we can actually see I think the former is the more probable.

 

Anyway all speculation and as such we ought to leave it there.

[Michael Crofts]

Cheltenham Spa. Name is Alstone Carriage Sidings.

Used to turnback service from/to London Paddington.

Was also used by services from/to Newport, Cardiff & Maesteg but since Covid they seem to terminate at Gloucester - or am I behind the times with that?

 

Edited January 17, 2022 by Michael Crofts
Annotated the track plan