How best to set out a junction?

[teaky]

Please may I pick the collective brains of RMwebbers.

 

Scenario: twin track main line dividing into four track mainline (fast lines in the middle and slow lines on the outside) at the same time as a branch line connects.

 

Which one of these formations would be most prototypical?  A using two double slips, B using two crossings, or another arrangement altogether?

 

 

Note: The diagrams are simplified and the four track section will be much longer.

Edited July 27, 2019 by teaky

[Flying Pig]

I think A would be ok if you used trailing single slips to form the crossover, but double slips on anything but low speed lines were very unusual.  Otherwise, plain diamonds and a separate trailing crossover would be fine.

 

You also need to connect the dangling end of the bottom slow line to the main with a plain point to the right of the junction.

[micknich2003]

The attached rough sketch of Staddlethorpe Junction may be of some use, it was typical NERly practice to have the trailing crossover as a trailing single slip.

[teaky]

57 minutes ago, Flying Pig said:

I think A would be ok if you used trailing single slips to form the crossover, but double slips on anything but low speed lines were very unusual.  Otherwise, plain diamonds and a separate trailing crossover would be fine.

 

You also need to connect the dangling end of the bottom slow line to the main with a plain point to the right of the junction.

Thanks Simon.  It was my unease around using double slips that prompted the question.

 

Dangling end - yes, I'd just substituted crossings and missed that key point.

[teaky]

15 minutes ago, micknich2003 said:

The attached rough sketch of Staddlethorpe Junction may be of some use, it was typical NERly practice to have the trailing crossover as a trailing single slip.

 

Thanks Mick.  That's a well matched example.

 

Does lever 37 control a catch point to protect the down slow from anything parked in the siding?

 

Forgive my ignorance, what are 5 and 55?

 

Interesting that trains from/to the branch could go via the fast and slow lines.  I'll give that some thought.

[micknich2003]

Levers 5 and 55 are Detonator placers, for model purposes forget them.  Yes, No37 is a Trap to protect the Down Slow.

[teaky]

Ah, good.  I guessed correctly then.

 

I'll go and read up on 'trap' and 'catch' points now.  I am aware it is a topic that crops up now and again but it's time I paid attention.

[jpendle]

If you are modelling a modern prototype then crossovers have also been getting the heave-ho. The 6 track line south of Wigan NorthWestern doesn't have any crossovers as it gradually reduces back to a 2 track main at Golborne Junction.

Lots and lots of ladders to cross between Up and Down, Freight, Fast, & Slow lines and at the very end a nice long ladder to reduce the 6 lines back down to two.

 

Regards,

 

John P

[Grovenor]

Modern prototypes have lost of crossovers, the heave-ho is for diamond crossings, with or without slips. The ladders you refer to are comprised of crossovers and or individual turnouts.

Crossover is a means of moving from one track to a parallel track via two turnouts.

Diamond Crossing is where two tracks cross.

[teaky]

I ought to have mentioned in my OP.  It is 1930s LNER.

[caradoc]

Drem, in Scotland, has the layout you require, ie Up and Down main lines with Up and Down Loops, and a single track branch (to North Berwick) diverging at the end of the Up Loop. Nowadays there are just simple crossovers, no slips or diamonds, however I imagine there would have been in the 1930s (although I'm not sure whether the North Berwick branch was single back then).

 

[bécasse]

If it is 1930s LNER, I would definitely go for layout B either with two diamond crossings or with one diamond crossing plus one single slip allowing arriving branch trains access to the fast line platform. I would also add a trailing crossover at the left hand end of the layout as it would facilitate shunting a terminating branch train (even if most ran through).

The other thing is that the branch should be double track in the vicinity of the station, even though it singles eventually, because the Board of Trade strongly disliked what it thought of as single line junctions. Ideally the double line would be long enough to hold a departing branch train while it was waiting for a late-running branch arrival to clear the single line, but even moving the diverging point off the single line back a couple of lengths would give the right impression.

 

[teaky]

3 hours ago, caradoc said:

Drem, in Scotland, has the layout you require, ie Up and Down main lines with Up and Down Loops, and a single track branch (to North Berwick) diverging at the end of the Up Loop. Nowadays there are just simple crossovers, no slips or diamonds, however I imagine there would have been in the 1930s (although I'm not sure whether the North Berwick branch was single back then).

 

Thanks caradoc.  A quick look at the aerial view it suggests the layout might have been changed in accordance with what jpendle and grovenor posted earlier.

[teaky]

41 minutes ago, bécasse said:

If it is 1930s LNER, I would definitely go for layout B either with two diamond crossings or with one diamond crossing plus one single slip allowing arriving branch trains access to the fast line platform. I would also add a trailing crossover at the left hand end of the layout as it would facilitate shunting a terminating branch train (even if most ran through).

The other thing is that the branch should be double track in the vicinity of the station, even though it singles eventually, because the Board of Trade strongly disliked what it thought of as single line junctions. Ideally the double line would be long enough to hold a departing branch train while it was waiting for a late-running branch arrival to clear the single line, but even moving the diverging point off the single line back a couple of lengths would give the right impression.

 

Thanks bécasse.  The four tracks are a section of main line and not a station.  I don't wish to upset the BoT but I am limited in how far I can move the diverging point away from the junction.  However, I'll move it towards the upper right as far as I can and move the points linking the upper slow and fast lines leftwards so that there is a loop before the branch (diverging) point which is long enough to hold a branch-sized train.

[The Stationmaster]

40 minutes ago, teaky said:

Thanks bécasse.  The four tracks are a section of main line and not a station.  I don't wish to upset the BoT but I am limited in how far I can move the diverging point away from the junction.  However, I'll move it towards the upper right as far as I can and move the points linking the upper slow and fast lines leftwards so that there is a loop before the branch (diverging) point which is long enough to hold a branch-sized train.

What matters is that it is a double line connection to the branch and that it only goes down into single line once it is on the branch.  There was never any requirement to provide sufficient length to stand a train between the junction out of the double/multiple line and the point where the branch reduced to single line.   Numerous junctions., in  fact probably the vast majority of them (including examples on former GNR lines), never had such a facility.

 

Look at item  No.10 in this document. (Item No9 applies to trains standing at station platforms so would be irrelevant in the case of most junction unless the junction points lie right at the end of the platform - and even then it wouldn't have much impact at most places)

 

https://www.railwaysarchive.co.uk/documents/BoT_Requirements1902.pdf

Edited July 28, 2019 by The Stationmaster
Correct typos

[Flying Pig]

57 minutes ago, The Stationmaster said:

What matters is that it is a double line connection to the branch and that it only goes down into single line once it is on the branch.  There was never any requirement to provide sufficient length to stand a train between the junction out of the double/multiple line and the point where the branch reduced to single line.   Numerous junctions., in  fact probably the vast majority of them (including examples on former GNR lines), never had such a facility.

 

In connection with which see the photo of Broome Junction on this page where the single line points on the left hand branch are about as close as it's possible to get to the junction (closer than could be achieved with Peco pointwork).  This is actually a junction between two single lines: the continuation of the right hand track beyond the crossover is a siding.

[DCB]

Going back to the OP I feel A will work better with better running through a Peco double slip than through the Peco long crossing together with the flexibility to run to from the branch from main or loop  but they didn't like facing points/ facing slips on main lines in NER or LNER days.

I think B would be massively frustrating to the blokes in the 1930s  as they would end up with freights unable to wait in the loops as they would prevent access or egress to  the branch. Saddlethorpe and having a train length of double road on the branch would have made life a lot easier.