Lack of clearance between tracks

[netek]

I'm looking for examples (drawings/plans/photos) of lack of clearance between two ostensibly independent tracks, requiring coordination of train movement on these tracks. How is this kind of situation handled from and operational/interlocking perspective?

Thanks

 

[Joseph_Locke]

I'm looking for examples (drawings/plans/photos) of lack of clearance between two ostensibly independent tracks, requiring coordination of train movement on these tracks. How is this kind of situation handled from and operational/interlocking perspective?

Thanks

Look no further than the Maryport & Carlisle route, pretty near three fourfoots!

Anything even slightly odd required the other line clearing and blocking - See the LNW(N) SA, which says:

Restricted clearances exist between certain trains and infrastructure on this section of line. Except for trains where the coaching stock is formed exclusively from passenger carrying vehicles fitted with window bars, the operation of a Departmental or passenger train movement that includes within the formation any passenger carrying vehicles with drop light windows (including Mark 2 air conditioned vehicles), is only authorised between Maryport and Carlisle (in either direction), subject to the timely and formal issue of a Special Notice to all parties that MUST include the following:
• The Person in Charge of the train must ensure that all droplight windows are closed and that they remain closed.
• The Person in Charge of the train must also ensure that the persons occupying the vehicles have been advised not to lean out or extend anything out of any window.
• In connection with the operation of a train comprised of Mark 2 air conditioned vehicles, the organiser must arrange for Stewards to be positioned at each door of every vehicle to enforce the restriction.
• The Person in Charge of the train must brief everyone on board, including the Train Crew, to ensure these instructions are adhered to.
Compliance to the above especially amends ‘Table D3 – Route clearance of coaching stock’ as published in Module NWRC of the LNW(N) Sectional Appendix.

 

[Railsigns]

I'm looking for examples (drawings/plans/photos) of lack of clearance between two ostensibly independent tracks, requiring coordination of train movement on these tracks. How is this kind of situation handled from an operational/interlocking perspective?

This occasionally happens on a temporary basis, usually for repairs on a viaduct. In some cases, the two tracks may be interlaced with each other.

Generally speaking, a temporary alteration to the signalling is needed. If the site is somewhere within an Absolute Block section, the easiest solution is to interlock the block instruments so that trains can't be signalled on both lines simultaneously.

 

[philthetube]

Does the lower section of the Great Orme Tramway count?

 

[hassaanhc]

Could this be the case for trains from Norbiton joining the mainline (Up Main Slow) at New Malden? Don't use that line often, but on countless occasions we've waited before the junction only for a train on the Up Main Fast to pass before we could proceed.

 

[QueensCurve]

I'm looking for examples (drawings/plans/photos) of lack of clearance between two ostensibly independent tracks, requiring coordination of train movement on these tracks. How is this kind of situation handled from and operational/interlocking perspective?

Thanks

I seem to recall Grimsby to Cleethorpes used by blocked to other traffic when an HST was on route around about 1983ish.

 

[pdeaves]

The St Mary's chord, that used to connect London Underground's East London and District lines, was double track so closely spaced that only one train was permitted at any time. In practice it didn't matter much as it was only used for stock transfer.

 

[edwin_m]

Does the lower section of the Great Orme Tramway count?

No, because the two vehicles are fixed to a cable that goes over a pulley at the top of the section. So they can only ever pass each other at the passing place, where there is enough clearance to do so. Unless the cable breaks and the various brakes all fail, in which case track spacing is probably the least of your problems.

 

[ilkestonian]

Is my memory correct regarding an under bridge somewhere on the route out of Buxton (towards Manchester) over which the two tracks were interlaced?

I'm thinking back to the 1970s or thereabouts and I seem to recall seeing it whilst seated at the back of a DMU on that service, so had a view of the receding tracks.

 

[najaB]

Is my memory correct regarding an under bridge somewhere on the route out of Buxton (towards Manchester) over which the two tracks were interlaced?

I don't know the answer, but just wanted to throw the term 'gauntlet track' out there as what you are describing.

 

[jopsuk]

there's a bit of gauntlet track on Tramlink, at Mitcham- for a short stretch it's much cheaper than proper single track as you avoid the use of points

 

[ac6000cw]

The term 'gauntlet track' covers both the situation where two otherwise independent lines are interlaced (usually without switches) e.g. the Tramlink arrangement:

(from Wikipedia)

...and 'switched' arrangements on a single track to provide more or less clearance for some types of train e.g. a US example to bring passenger trains closer to a high platform:

(from Wikipedia)

See https://en.wikipedia.org/wiki/Gauntlet_track

 

[themiller]

Look no further than the Maryport & Carlisle route, pretty near three fourfoots!

Anything even slightly odd required the other line clearing and blocking - See the LNW(N) SA, which says:

I was told that, when the platforms at Aspatria were rebuilt, the work party used a p/way trolley which fitted nicely on the adjacent rails of the up and down tracks. Thus at Aspatria, the six foot is really four foot (81/2")!

 

[duffield]

There's an interlaced track section at 'The Forest' tram stop in Nottingham:

http://www.thetrams.co.uk/net/pictures/000105
http://www.thetrams.co.uk/net/pictures/000108

 

[tsr]

There's an interlaced track section at 'The Forest' tram stop in Nottingham:

http://www.thetrams.co.uk/net/pictures/000105
http://www.thetrams.co.uk/net/pictures/000108

Unlike the Mitcham example on Tramlink, it looks to me like that track may be interlaced to position the points away from both the curves leading to the platforms, and the road junction / pedestrian crossing that the trams have to cross.

(However, I still would have thought there would be space for a set of points like there is to the right hand side of the photo. This is what makes me so uncertain, really.)

Does anyone know if I'm correct in thinking this?

 

[ac6000cw]

Unlike the Mitcham example on Tramlink, it looks to me like that track may be interlaced to position the points away from both the curves leading to the platforms, and the road junction / pedestrian crossing that the trams have to cross.

(However, I still would have thought there would be space for a set of points like there is to the right hand side of the photo. This is what makes me so uncertain, really.)

Does anyone know if I'm correct in thinking this?

According to this - https://en.wikipedia.org/wiki/Gauntlet_track#United_Kingdom - yes, it's to avoid the road junction.

 

[bramling]

The St Mary's chord, that used to connect London Underground's East London and District lines, was double track so closely spaced that only one train was permitted at any time. In practice it didn't matter much as it was only used for stock transfer.

Further to add to this, during the 1990s a modification was done to the interlocking in Whitechapel Signal Box so that signals couldn't be cleared both ways at the same time.

 

[Deepgreen]

Could this be the case for trains from Norbiton joining the mainline (Up Main Slow) at New Malden? Don't use that line often, but on countless occasions we've waited before the junction only for a train on the Up Main Fast to pass before we could proceed.

No - that's a standard separation site. Probably an up slow train ahead needing to clear the section, with the overtaking train just a coincidence.

 

[QueensCurve]

There's an interlaced track section at 'The Forest' tram stop in Nottingham:

http://www.thetrams.co.uk/net/pictures/000105
http://www.thetrams.co.uk/net/pictures/000108

This exists on the tramlines in Amsterdam too.

 

[snowball]

There's a new gauntletted switch in the St Peter's Square/Moseley Street area for Manchester Metrolink's first and second city crossings.

 

[edwin_m]

It's a combination of wanting to keep the moving parts out of the main traffic lane, but also making sure they don't have to move until the tram is very close, so that there is unlikely to be anybody standing on them. If they were on the far side of the road and didn't move when commanded then the tram would end up stuck across the road.

 

[Joseph_Locke]

I was told that, when the platforms at Aspatria were rebuilt, the work party used a p/way trolley which fitted nicely on the adjacent rails of the up and down tracks. Thus at Aspatria, the six foot is really four foot (8 1/2")!

There was a photo of this in the PWSS's office at Carlisle - three "bogies" on two tracks.

 

[edwin_m]

I was told that, when the platforms at Aspatria were rebuilt, the work party used a p/way trolley which fitted nicely on the adjacent rails of the up and down tracks. Thus at Aspatria, the six foot is really four foot (81/2")!

I read somewhere the Liverpool and Manchester was originally built like that, so that when a large load needed to be carried, the train could be run on the middle pair of rails.

 

[button_boxer]

It's a combination of wanting to keep the moving parts out of the main traffic lane, but also making sure they don't have to move until the tram is very close, so that there is unlikely to be anybody standing on them. If they were on the far side of the road and didn't move when commanded then the tram would end up stuck across the road.

There's a similar set up at Hillsborough on the Sheffield Supertram, presumably for the same reason. The points for the junction towards Malin Bridge are in the segregated section just after the end of the platform, then there's interlaced track from there the 30 yards or so to the actual turning which is in the middle of a busy junction.

 

[Ships]

Holme tunnel prior to rebuild had clearances so tight that only one train would be allowed through the tunnel at one time.

 

[Holly]

...
...and 'switched' arrangements on a single track to provide more or less clearance for some types of train e.g. a US example to bring passenger trains closer to a high platform:

(from Wikipedia)
See https://en.wikipedia.org/wiki/Gauntlet_track

So could this arrangement be used to platform UIC gauge passenger trains at the existing Crewe station?

 

[najaB]

So could this arrangement be used to platform UIC gauge passenger trains at the existing Crewe station?

Could be, yes. But Crewe is an awful station from an track point of view, even before adding in more S&C.

 

[Dr_Paul]

Could this be the case for trains from Norbiton joining the mainline (Up Main Slow) at New Malden? Don't use that line often, but on countless occasions we've waited before the junction only for a train on the Up Main Fast to pass before we could proceed.

The idea that there may be a lack of clearance between the up fast and up slow at New Malden is a bit odd: I very much doubt that this is the case. I used to commute up to Waterloo that way for many years; I've been held quite a few times there, but on other times have gone up the gradient into New Malden station without being held, and often being overtaken by trains on the up fast. I suspect that up Kingston trains are held because of preceding services from Surbiton on the up slow, some of which stop at New Malden.

 

[Hophead]

Add Church Street, Croydon, to the list of tram lines with interlaced track.

Google Streetview (but note you can't go up Church Street itself for a closer look).

 

[Joseph_Locke]

Could be, yes. But Crewe is an awful station from an track point of view, even before adding in more S&C.

But even then they couldn't pass on adjacent lines, and I suspect the roof columns would have to be removed too...