Freight Passing Loops, Laybys, etc.

[scottystitch]

Okay, this may be a stupid question time.

 

My layout plan includes a twin track mainline, with a passing loop/layby, to allow faster traffic to overtake slower freight trains, on the up side only. My plan has this section of track on an incline of 0.8%, i.e. 1 in 125, with the up line layby facing down hill.

 

My question is, what is the situation with this prototypically? were laybys usually located on level ground or is it okay to have it on the incline?

 

Thanks in anticipation.

 

Best

 

Scotty

[LMS2968]

They were generally parallel and close to the running line, so would be on the same gradient. Usually, they were accessed at the exit end only so trains had to set back into them; facing points on running lines were largely disapproved of, but there were exceptions: south of Tebay, the Down lay by siding was converted from single entrance to double entrance. There would be trap point protection at each end, irrespective of the direction of the gradient.

[beast66606]

A lay-by or lie-by was a dead end where the train ran passed and then set back into the siding.

 

A loop had a facing connection and the train could run straight into it.

 

As LMS says you will need traps at the end(s)

[Edwin_m]

They were generally parallel and close to the running line, so would be on the same gradient. Usually, they were accessed at the exit end only so trains had to set back into them; facing points on running lines were largely disapproved of, but there were exceptions: south of Tebay, the Down lay by siding was converted from single entrance to double entrance. There would be trap point protection at each end, irrespective of the direction of the gradient.

This statement depends on era and to some extent on company.  "Running Loops" with access both ends became more common in later years, partly because of less concern about facing points and to reduce the amount of time the main line was blocked when the freight set back into the siding.  Diagrams on signalbox.org are a good source of information on the practices of a particular company/region at a particular time. 

 

Summits are good places for loops because the train will be approaching slowly up the gradient and departing on the down grade helps it accelerate.  Loops may also be found at the bottom of inclines, probably so the freight can wait there for other trains to pass and for a banking engine to be available before it starts its slow climb.  Can anyone think of an example of a loop part way up a severe gradient? 

[beast66606]

This statement depends on era and to some extent on company.  "Running Loops" with access both ends became more common in later years, partly because of less concern about facing points and to reduce the amount of time the main line was blocked when the freight set back into the siding.  Diagrams on signalbox.org are a good source of information on the practices of a particular company/region at a particular time. 

 

Summits are good places for loops because the train will be approaching slowly up the gradient and departing on the down grade helps it accelerate.  Loops may also be found at the bottom of inclines, probably so the freight can wait there for other trains to pass and for a banking engine to be available before it starts its slow climb.  Can anyone think of an example of a loop part way up a severe gradient? 

 

Thrimby Grange on the Southbound ascent of Shap has an Up loop (only - no down)

 

I think loops became more popular as the working distance of points away from boxes increased to 350yds, meaning the loops could be 600/700 yds long and controlled from a single box whereas previously a long loop would need a box at each end.

[luckymucklebackit]

This statement depends on era and to some extent on company.  "Running Loops" with access both ends became more common in later years, partly because of less concern about facing points and to reduce the amount of time the main line was blocked when the freight set back into the siding.  Diagrams on signalbox.org are a good source of information on the practices of a particular company/region at a particular time. 

 

Summits are good places for loops because the train will be approaching slowly up the gradient and departing on the down grade helps it accelerate.  Loops may also be found at the bottom of inclines, probably so the freight can wait there for other trains to pass and for a banking engine to be available before it starts its slow climb.  Can anyone think of an example of a loop part way up a severe gradient? 

 

Can't think of a loop on a climb, but there was Greskine Refuge Siding on the Climb to Beattock.

 

Jim

[scottystitch]

Can't think of a loop on a climb, but there was Greskine Refuge Siding on the Climb to Beattock.

 

Jim

 

Maybe I'm over thinking things. is 1 in 125 considered an inclination of concern? I'm aware Beattock, for instance, has passing loops at its summit, but that is in the middle of some pretty severe gradients.

 

My loop has a facing point for entry, rather than having to reverse, and the whole section of trackwork is controlled by a remote powerbox.

 

I think I'll stick with it.

 

Thanks for the replies.

[Phil Bullock]

Maybe I'm over thinking things. is 1 in 125 considered an inclination of concern? I'm aware Beattock, for instance, has passing loops at its summit, but that is in the middle of some pretty severe gradients.

 

My loop has a facing point for entry, rather than having to reverse, and the whole section of trackwork is controlled by a remote powerbox.

 

I think I'll stick with it.

 

Thanks for the replies.

 

Plenty of prototypes on that sort of gradient am sure - including down goods loop at Abbotswood Junction which is on an up hill gradient, summit and exit at the junction itself. Don't forget the entry point will need point locking arrangements if traversed by passenger traffic. 

 

Kind regards

 

Phil

[Rugd1022]

Maybe I'm over thinking things. is 1 in 125 considered an inclination of concern? I'm aware Beattock, for instance, has passing loops at its summit, but that is in the middle of some pretty severe gradients.

 

My loop has a facing point for entry, rather than having to reverse, and the whole section of trackwork is controlled by a remote powerbox.

 

I think I'll stick with it.

 

Thanks for the replies.

 

1 in 125 is quite steep in real terms, the climb out of Northampton up to Roade Cutting is 1 in 200 and it's a fair old slog on full power with a heavy train. Not as hard going as the Lickey though, which is 1 in 37!

 

Edited to add : I'm pretty sure the old loops either side of the Midland Mainline at Wistow and Desborough were at least partially laid on gradients.

Edited January 15, 2018 by Rugd1022

[johnlambert]

There's a loop on Hatton Bank where slow trains can be passed by faster traffic. I can't remember the gradient, but it's certainly not flat.

[Edwin_m]

I think loops became more popular as the working distance of points away from boxes increased to 350yds, meaning the loops could be 600/700 yds long and controlled from a single box whereas previously a long loop would need a box at each end.

I was thinking that too.  Under Absolute Block would they still need a box at the entrance to the loop to observe the tail lamp of a train before confirming it was "inside", or would they rely on some sort of communication from the guard to confirm the train was all present and correct?  If so then loops would tend to be "staggered" with both entrances in the same place (by the box) but if they are provided in both directions they are generally opposite each other.  On the other hand a box controlling refuge sidings would be next to the pointwork so the signalman could observe trains directly and work the points mechanically, so would be adjacent to the "finish" of the siding in the direction of travel. 

Edited January 15, 2018 by Edwin_m

[LMS2968]

The gradient of the line approaching Ecclefechan was 1 in 200 down towards Carlisle. The report into the collision there on 23 July 1945 at the lay-by sidings - http://www.railwaysarchive.co.uk/documents/MoT_Ecclefechan1945.pdf - states this.

[Rugd1022]

There's a loop on Hatton Bank where slow trains can be passed by faster traffic. I can't remember the gradient, but it's certainly not flat.

 

Can't believe I forgot to mention this one.... I sign the road! It gets steeper towards the top then flattens our close to the station, the line speed is only 10mph throughout, crawling up there is tedious beyond belief.

[The Stationmaster]

Maybe I'm over thinking things. is 1 in 125 considered an inclination of concern? I'm aware Beattock, for instance, has passing loops at its summit, but that is in the middle of some pretty severe gradients.

 

My loop has a facing point for entry, rather than having to reverse, and the whole section of trackwork is controlled by a remote powerbox.

 

I think I'll stick with it.

 

Thanks for the replies.

 

A gradient of 1 in 125 is officially 'a steep gradient' within the meaning of all sorts of past operating Instructions and the Dept of Transport 'Requirements.  .... etc'.  The official definition of a steep gradient is one of 1 in 260 or steeper and in many places setting back towards (but not necessarily onto) a steep gradient was prohibited although at others it was allowed with the caveat 'extra care to be exercised when setting back towards ..... '

There's a loop on Hatton Bank where slow trains can be passed by faster traffic. I can't remember the gradient, but it's certainly not flat.

1 in 108, steepening to 1 in 103 then easing out to 1 in 110 on the last stretch towards Hatton station.  I would think that the loop as it stands nowadays is entirely on the 1 in 110 portion.

I was thinking that too.  Under Absolute Block would they still need a box at the entrance to the loop to observe the tail lamp of a train before confirming it was "inside", or would they rely on some sort of communication from the guard to confirm the train was all present and correct?  If so then loops would tend to be "staggered" with both entrances in the same place (by the box) but if they are provided in both directions they are generally opposite each other.  On the other hand a box controlling refuge sidings would be next to the pointwork so the signalman could observe trains directly and work the points mechanically, so would be adjacent to the "finish" of the siding in the direction of travel. 

 

The arrival of hand generators to work point machines made the whole provision of facing entrances lot more feasible.  the usual procedure was to provide a 'hone near the entrance to the loop, and/or where the rear end of most trains would come to a stand, for the Guard to report 'in clear' to the Signalman.  A problem of course arose if the Guard 'forgot' to use the 'phone and then delay to following trains would occur.  If the 'loop' was between two successive signalboxes it technically ceased to be a loop and was classified as running line because different Rules & Regulations applied.

[LNERGE]

Littlebury bank had an up loop. Here is a picture of the distants for the intermediate block homes that controlled the exit..

 

https://www.flickr.com/photos/140616380@N03/39564527482/

 

I have gone for this view as it gives a glimpse of the lineside phones used to summon assistance if a train got into difficulties on the bank.

[scottystitch]

The following Anyrail captures will illustrate things, I think.

 

This is N gauge. The first image shows just the main line and the loop. I appreciate the spacing between the UP line and the loop, it's just a rough draft.

 

The second image shows the loop in the context of the more of the layout. The line enters a tunnel in the top left hand corner, and then exits just as the twin track expands into a station approach. In pretend world, this tunnel will be around half - three quarters of a mile long.

 

The purpose of the loop is to hold freight trains waiting for a path to traverse the station approach and onto the through lines, avoiding the terminus  T