Semaphore Signal Box minimum clearances

[wasdavetheroad]

I am trying to squeeze an old style signal box between a main running line and a goods yard track. Is there a specified minimum clearance between the box wall and the centre of the running line allowing for the point rodding emerging from the box etc. The model is a 00 scale Metcalf kit with a width of approx 13 feet plus a 18 inch walkway for cleaning the windows

[Miss Prism]

Trackcentre to building clearance is usually 7'6"

 

[TheSignalEngineer]

 

The box structure should at a minimum comply with this diagram. The desirable clearance is as shown by the red line

 

 

[wasdavetheroad]

Thanks for the info. Due to the inevitable depth constraints with baseboard depth it looks like there is not enough room. My alternative is to move the yard track closer to the running line and locate the box behind it whilst maintaining the line of sight to the various signals if possible.

 

I suppose it is OK to have the point rodding etc running under what is the access road to the yard. When I get round to the rodding in a year or so.

[TheSignalEngineer]

37 minutes ago, wasdavetheroad said:

 

I suppose it is OK to have the point rodding etc running under what is the access road to the yard. When I get round to the rodding in a year or so.

Perfectly O.K. The first track in front of the box in this view is the shunt neck for Duddeston Sidings at Saltley which was the yard for incoming coal at Nechells Gas Works. The next two were the Lawley Street Goods lines then the Up Main line. 

https://warwickshirerailways.com/lms/mrsalt618.htm

Edited October 28, 2021 by TheSignalEngineer

[LNERGE]

Fit a box with a narrow base like Melton Mowbray or put the box on legs like Peterborough East.

Edited October 29, 2021 by LNERGE

[wasdavetheroad]

I could do that but there is no site width restriction in the real world site which is a country area. The maximum baseboard width is 36'' which is just about reachable as I am less than 5' 5''. Overall design constraints on the layout mean I can't find an extra few inches here without causing even worse problems elsewhere. The Metcalfe box is being recycled from a previous layout as well.

[ISW]

18 hours ago, wasdavetheroad said:

Is there a specified minimum clearance between the box wall and the centre of the running line allowing for the point rodding emerging from the box etc.

I was under the impression that you were allowed to be under the 'normal' minimum clearance for short lengths (eg: an overbridge, small building), so long as you installed 'Limited Clearance' signs (those white / red diagonal rectangles) at each end as a warning not to loiter beside the structure. Not ideal for a signalbox where you need access for maintenance of the rodding emanating from the building, but maybe acceptable for a model layout.

 

Ian

[TheSignalEngineer]

On 29/10/2021 at 09:41, ISW said:

I was under the impression that you were allowed to be under the 'normal' minimum clearance for short lengths

Historically clearances were tighter but the requirement on new work had been in place since at least 1885. This shows the actual paragraph marked up for the 1902 proposed amendments.

 

The 2 feet 4 inches is exactly the same as the 1950 requirements. 

 

 

Edited April 10, 2022 by TheSignalEngineer

[TheSignalEngineer]

2 hours ago, wasdavetheroad said:

I could do that but there is no site width restriction in the real world site which is a country area.

Can you modify the base of the box like this which had the front wall set back a few inches to give the clearance. If you put it between the main line and siding it would depend on which side the frame is. Thin it down on the other side to maintain working space downstairs.

 

https://thetransportlibrary.co.uk/?route=product%2Fsearch&search=Norton Junction No 1

 

Norton Junction No.1 was thinned on the frame side so had doors in the front to access the equipment from that side when necessary. 

 

Another of my old haunts was Saltley Sidings which stoon between the Up Nain and Down Main

 

R1298 - Saltley Sidings by Bill Wright, on Flickr

[Reorte]

Maybe not an answer you want but if you're having to compress anyway to fit in to your space then maybe just accepting you can't do things to prototype rules and standards is a compromise worth living with. Could the box be narrowed a little without being too obvious? Or compromise on the clearance (whilst obviously still leaving enough room to physically fit) on the side facing away from the direction you'll usually view the layout from? Not ideal I know.

[wasdavetheroad]

Yes there are lots of compromises due to available space and my choice of KATO HO Unitrack for this my 3rd layout. Age related hand and eye issues have led to me choosing the simplest approach which gives the project its working name of the '16 foot train set'. I don't like wiring anyway and the baseboards are 3 layers of 50mm blue foam screwed together. I changed to wireless control and battery power with the last layout and it has worked well for me.

 

I took delivery of the final 3 points last week so hopefully will start track laying in a couple of weeks once some building work is completed.

 

Back to the signal box. This morning I modified the yard layout and the plan shows in red where I wanted the box to be and in green where I will try it first. Some of you might recognise the layout from my signalling forum question and note I took the good advice to put a run around loop in for the mineral exchange sidings. This will allow for the little 0-4-0 to run around 6 wagons which is fine for me and even an excuse to make 2 trips to fill the sidings.

 

 

[TheSignalEngineer]

Is it possible to transpose the point ad short curve in the siding then realign the siding to give wider spacing for the red signal box position? I can clearly remember working at a box like that where the line had a distinct kink round it but can't find a picture at the moment.

[wasdavetheroad]

I will try experimenting with AnyRail for that idea. There is the restriction of very limited turnout geometry. Currently only 867mm radius with a 10 degree diverge or 490mm radius with a 25 degree diverge, new 550 rad are in production soon. It could be expensive as well, those 867mm points include built in motor and other track sections but come in at £60 a pop! Maybe one day they will introduce a 'Y' point like they have in their N-scale range. I calculate I would need 112mm between track centres to fit the signal box. Also the large space in the yard near the red box is where the cattle pens and loading dock are located.

 

BTW the mineral run around loop has 2 x 490 rad points at one end and I cut down the curve to about 21 degrees to narrow the track separation.

[TheSignalEngineer]

My thought was something like this

 

[TheSignalEngineer]

A possibly better variation, but i haven't checked how much space it gives.

 

Edited April 10, 2022 by TheSignalEngineer

[wasdavetheroad]

Thanks for the designs, the second one looks better. I have redrawn it with the clearances I need, 112mm for the box and 180mm for the cattle/loading dock. This would mean buying an additional turnout and discarding one with the problem of maybe waiting months for delivery. I can delay the decision as the advantage of sectional track is I can easily lift it as I experiment with operating the layout

 

 

[47406]

I had the same scenario, i laid track and then turned my attention to where to put signal boxes and yes indeedy, found myself looking at a couple of spots where the I would like to put the boxes but would be in between running lines and sidings.

 

I moved one sidings back and curved it a bit, but it still felt a little tight. Then I remembered pictures of Westbury before the resignaling & went hunting for photos online - check these out:

 

 

check it out from the South side, even tighter !

 

 

[wasdavetheroad]

That's interesting, the point rodding can emerge from any side of the box and maybe even all of them!

[SM42]

Another worth looking up for being squeezed in is Lichfield Trent Valley low level.

Situated between the up and down fast lines there wasn't a lot of space.

 

It was a real roller coaster ride when a train passed. 

 

Andy

[Michael Hodgson]

1 hour ago, wasdavetheroad said:

That's interesting, the point rodding can emerge from any side of the box and maybe even all of them!

It can indeed.  Point rodding and signal wire runs are a study in themselves.  

Wooden covers are quite common (heavy planking so that S&T can easily get access for maintenance) and enables the rodding to be walked over.  Where rodding emerges from the front of the box, it usually either immediately turns through 90 degrees with a crank to run parallel to the track, or it might run under the track to the opposite side of the line if that is more convenient.  The space used by the rodding run might well need to occupy that gap between the structure and the nearest track. 

 

And in the case of boxes on stilts, the rods & wires have to emerge vertically from the bottom of the box.

[ISW]

2 hours ago, SM42 said:

Another worth looking up for being squeezed in is Lichfield Trent Valley low level.

Situated between the up and down fast lines there wasn't a lot of space.

Andy,

 

You mean like this photo of mine from January 1978 of Class 87 87009 on 09:12 Manchester to Euston:

 

Ian

[TheSignalEngineer]

That one was a bit hair raising to be in when an express passed. Probably even more so on the occasion it got clipped by a freightliner container.

[SM42]

3 hours ago, ISW said:

Andy,

 

You mean like this photo of mine from January 1978 of Class 87 87009 on 09:12 Manchester to Euston:

 

Ian

 

That's the one

 

1 hour ago, TheSignalEngineer said:

That one was a bit hair raising to be in when an express passed. Probably even more so on the occasion it got clipped by a freightliner container.

 

It was certainly fun to sit at one end and watch the ripple come down the box towards you.

 

Freightliners were even more fun as gaps between containers created more ripples. 

 

Spent a few happy weeks there. 

 

Andy

[TheSignalEngineer]

This one looks a bit tight at first sight but in reality had plenty of space.