Help required with Signalling

[richscylla]

Hi all, 

 

I'm putting together the plan for a new layout and I could with some help to create some prototypical signalling. 

I have attached the track plan, it's a fairly simple one so hopefully the signalling should be fairly simple too. The siding/depot will be accessed off the main line either with a reversing manoeuvre from the down, or across the points from the up. 

It would be great to know where the signalling (and what kind) I need on the mainline and then what ground signals I need in the depot. 

 

If you have any questions, please let me know. 

 

Rich 

[Andy Hayter]

It might be helpful if you indicated your modelling period.  If you model modern image I suspect information regarding placement of lower quadrant signals will be less than helpful.  

[richscylla]

Sorry, you're right I should have mentioned that - it's 1990s!

[Nick C]

My first thought is that it's unlikely they'd have had a facing crossover there - more likely a trailing one, probably directly above the building in your plan, just as the main lines go straight again - so you'd have a reversing manouever from both lines - directly from the down, or reversing from up to down then running in.

 

What area are you modelling? Much of the country was colour light by the 90's, but there was still a lot of semaphore signalling around (I think there still is in places, there's even still lower-quadrant in Cornwall...). If colour light, the main line would have three or four aspect signals, probably only one in each direction visible on your model. The crossover and access/egress from the depot would, I think, be controlled with ground position-light signals - but others more versed in modern-ish practice might correct me there!

[richscylla]

Hi Nick, 

Thanks for taking the time to comment. 

 

Do you mean the crossover on the left hand side?

The layout would be South Wales between Bristol and Newport so would expect colour light signals.

Rich
 

[PaulRhB]

 

I’d suggest changing to a trailing crossover too. 

1 & 2 are main aspects with their overlaps clear of the new crossover. Let’s assume 1 on the Up line and 2 on the Down line. 

 

3 is a ground position signal (GPS) to control moves back onto the Down line from the Up. 

 

4 also a GPS controls moves into the depot and can only be cleared for a route set into the depot. 

 

5 another GPS, or only proceed with shunter permission sign, under the depot ground frame control for moves from the headshunt into the depot. 

 

6 GPS cleared by shunter for moves to the headshunt but under the control of the Signalbox for moves onto the mainline.

 

Would be likely there’s actually a catch point in the middle of the crossover you’ve drawn so the catch and mainline point work as a pair and the shunter also has to set the point at the depot end before a route can be set from 5 or 6 by the box. It’s that or some sort of interlock acceptance/ offer switch so the box can only reverse that crossover when authorised by the depot shunter. 

[The Stationmaster]

1990s WR - so why no facing crossover. (although you can't run round in the sidings so a loco would be trapped if did have one).  

 

Or you could have both because the main lines are reversibly signalled - I don't think anybody has modelled that yet.

[PaulRhB]

Trailing crossover is a bit more interesting operationally but as Mike says you can have facing ones. Does it limit line speed at all Mike? Plain crossovers tend to be relatively low speeds on the Southern, 40 or less on the straight route, with 15-20 over the crossover route.

You’d need a limit of shunt board clear of no.1’s overlap with a facing one for locos to shunt onto the Up line. 

 

[St. Simon]

2 hours ago, PaulRhB said:

Trailing crossover is a bit more interesting operationally but as Mike says you can have facing ones. Does it limit line speed at all Mike? Plain crossovers tend to be relatively low speeds on the Southern, 40 or less on the straight route, with 15-20 over the crossover route.

You’d need a limit of shunt board clear of no.1’s overlap with a facing one for locos to shunt onto the Up line. 

 

 

Hi Paul,

 

I've personally never heard of linespeed over points being governed by facing or trailing direction, I've only ever heard of the geometry of the point being the overriding factor, but you make a good point and an interesting question!

 

I know that there are 70mph facing cross overs on the Western, Severn Tunnel Junction being one location (I only remember that one as I've been looking at the scheme plan for it this week!

 

Simon

Edited August 10, 2019 by St. Simon

[PaulRhB]

They don’t like facing points on high speed lines because they take a battering from wheel hammer blow and need more maintenance to keep the switch tips in good order and the nose of the crossing. It’s not a speed because they are facing as such just high speed hammers the critical bits more and that matters in a facing set slightly more if you chip a bit off. That’s what I was told years back by Pway as they can cost less to maintain. 

[St. Simon]

51 minutes ago, PaulRhB said:

They don’t like facing points on high speed lines because they take a battering from wheel hammer blow and need more maintenance to keep the switch tips in good order and the nose of the crossing. It’s not a speed because they are facing as such just high speed hammers the critical bits more and that matters in a facing set slightly more if you chip a bit off. That’s what I was told years back by Pway as they can cost less to maintain. 

 

Ah, I see what you mean, yes, you're right, the ones at Tilehurst (only just thought of them even thought I live next to the line) are 125mph straight and 70mph divergent and they take a real hammering.

 

Simon

[The Stationmaster]

1 hour ago, St. Simon said:

 

Ah, I see what you mean, yes, you're right, the ones at Tilehurst (only just thought of them even thought I live next to the line) are 125mph straight and 70mph divergent and they take a real hammering.

 

Simon

And several of the reversible crossovers have long (c.30+ years)  had 125mph straight road line speeds through them.  As have quite a number of running junctions.

[TheSignalEngineer]

4 hours ago, St. Simon said:

I've personally never heard of linespeed over points being governed by facing or trailing direction,

Many years ago I remember when Clamp Locks were first introduced there were speed restrictions over them until experience was gained. One of the first sets was on a 40mph connection at Coventry station. I was later involved in a project which got approval for using them at 70mph in the facing direction.

[richscylla]

Really sorry, but what do you mean by facing and trailing crossovers?

[PaulRhB]

Facing the direction of travel so you can take either route or Trailing where you have to ‘trail’ through it then reverse to change route. 

[richscylla]

16 hours ago, PaulRhB said:

Facing the direction of travel so you can take either route or Trailing where you have to ‘trail’ through it then reverse to change route. 

Thanks for clearing this up Paul. And also thanks for the signalling diagram?

So it seems that whilst my plan is possible in the WR, it would be more likely done with a trailing cross over and a head shunt? I was ideally looking to be able to get units onto the siding so I might look to stick with the facing cross overs.