"Correct" way to lay out a junction

[whart57]

I'm thinking about a layout based on a junction where two single track lines join and continue as double track. I have drawn out two possible options. The question is, which is correct - one, other, neither or both?

 

 

The period I have in mind is circa 1875 when presumably regulations were a little looser, but any advice and suggestions would be welcome

[Neils WRX]

Option B is a bit over engineered with the left had end crossover.

 

Option A would be the more likely option.

 

Thanks,

 

Neil

[Michael Hodgson]

I would agree as the left hand crossover serves no useful purpose.

Is this an isolated junction, with no station?  

[meil]

You may care to look here: http://www.disused-stations.org.uk/b/broom/

 

at the south junction at Broom Junction.

[whart57]

3 hours ago, Michael Hodgson said:

I would agree as the left hand crossover serves no useful purpose.

Is this an isolated junction, with no station?  

 

The intention is that it is an isolated junction with the nearest station a mile or so away

[whart57]

2 hours ago, meil said:

You may care to look here: http://www.disused-stations.org.uk/b/broom/

 

at the south junction at Broom Junction.

 

Thanks for the link.

[MikeB]

It seems to depend on company and traffic levels.  There are various layouts, from a simple Y (Lossie Jn, Fodderty Jn) to something akin to B (Long Melford Jn 1912) , on https://signalbox.org/track-layouts/by-railway-company/  The two points and  a diamond seemed to be the favoured way for a branch by the time of nationalisation until simplification later in BR days. The trailing crossover may be useful is trains needed to reverse and go from one of the right hand single lines to the other one

[bécasse]

Post 1873 the Board of Trade required that remote junctions between two single track lines were made as double track junctions - so B, but you don't need the left hand end trailing crossover as part of the junction arrangement and, strictly speaking, the two double track sections on the single track branches should be long enough for trains to pass. The BoT might not have insisted on that though given the shared approach route was double track.

Option A would be typical of the last 50 years.

[Chris M]

2 hours ago, whart57 said:

 

The intention is that it is an isolated junction with the nearest station a mile or so away

In that case it might well be run as two parallel single lines from the station with no points at the deviation. By definition branch line traffic wouldn’t be heavy and if you have points at the station why go to the expense of more points and a signalman just down the road? I think that happened at Wadebridge.

[Tankerman]

10 minutes ago, Chris M said:

In that case it might well be run as two parallel single lines from the station with no points at the deviation. By definition branch line traffic wouldn’t be heavy and if you have points at the station why go to the expense of more points and a signalman just down the road? I think that happened at Wadebridge.

Yes it did.

[bécasse]

10 hours ago, Chris M said:

In that case it might well be run as two parallel single lines from the station with no points at the deviation. By definition branch line traffic wouldn’t be heavy and if you have points at the station why go to the expense of more points and a signalman just down the road? I think that happened at Wadebridge.

There were a number of examples of junctions between single track lines in the UK where, in accordance with BoT requirements, the actual junction was double track and Wadebridge was one of them. As has been suggested, the railway company(its) concerned often (and quite quickly) realised that the expense of maintaining a junction "out in the sticks" wasn't justified and resited the actual signalled junction to the nearest station with two separate single tracks from there to the point of actual divergence of the two routes. Again Wadebridge was one of the examples.

 

By the way, the reasoning behind the BoT requirements was that it was difficult (although not completely impossible) to ensure that trains weren't accepted from both ends of a single line route when there was a junction in the middle of that route. (In extremis, they could have been passed by routing one a short distance down the diverging route, and then reversing it back past the junction once the other train had passed. Quite rightly, the BoT disliked this solution, although I know of one instance of it happening regularly as late as the 1960s at Boscarne Junction where the afternoon Wadebridge-Bodmin General school train was recessed on the Bodmin North line to allow a Bodmin General-Wadebridge train to pass, there being no running loops.)

[caradoc]

12 hours ago, Chris M said:

In that case it might well be run as two parallel single lines from the station with no points at the deviation. By definition branch line traffic wouldn’t be heavy and if you have points at the station why go to the expense of more points and a signalman just down the road? 

 

That was the layout on the SMJ at Towcester; Originally there was a single line from Towcester to Greens Norton where the Banbury and Stratford routes diverged, with of course a box there (in fact, two boxes at first); In 1910 separate single lines were provided for each route with the junction, as opposed to divergence, now being at Towcester, where of course there had to be a box anyway. 

 

There was also the (unique ?) situation on the IoW at Smallbrook, which in the summer was a junction between a double and two single line routes, and the rest of the year just a divergence of two single lines. 

 

 

[KingEdwardII]

20 hours ago, whart57 said:

The question is, which is correct - one, other, neither or both?

Bewdley South on the SVR is effectively following option A:

 

https://www.svrwiki.com/Bewdley_South_signal_box#Diagram

 

OK, the second single line to Stourport has been long closed, but that link shows the pre-closure layout which matches the current one.

 

In this case, the junction is very close to Bewdley station, rather than being isolated in the countryside, but I think that the general principles still apply.

 

Mike

[whart57]

Thank you for this useful link

[KingEdwardII]

I did not spot this at first, but Bewdley North followed the same pattern - before closures, there were two separate lines to the north of Bewdley, both single track - the one to Bridgnorth which still exists and a second one to Cleobury Mortimer (what a name!) and Tenbury Wells which crossed the Severn not far north of Bewdley, long since closed.

 

Here's the signal box diagram:

 

https://www.s-r-s.org.uk/html/gws/S2647.htm

 

Bewdley station track diagram & signalling is curiously complex due to the loop line platform required to deal with the fact that the station was a junction both to the north and to the south.

 

Mike.

[Nick C]

On 13/03/2021 at 10:46, caradoc said:

There was also the (unique ?) situation on the IoW at Smallbrook, which in the summer was a junction between a double and two single line routes, and the rest of the year just a divergence of two single lines. 

 

That arrangement was much later though, post-grouping (and followed pretty much option A in the OP's post, though it was a scissors crossover rather than two separate ones).

 

Prior to the grouping, it was worked as two parallel single lines all the way to Ryde St Johns.