Reverse Direction Signalling Advice Needed

[LNERandBR]

Hello

 

I'm after some advice regarding signalling for reverse direction movements. The layout is roughly set between 1990 and 2000 using colour light signals.

 

Please see the rough trackplan below.

 

 

What we have here is a 4 track mainline reducing down to double track with an additional cross over. For normal running I belive 3 signals are required. These being positioned on tracks 1, 2 and 5. In addition the signal on track 5 would require a feather indicator.

I also require trains to be able to travel from track 4 to track 5 and back again. I know that this would require extra signals on tracks 4 and 5 to allow this.

 

Now the resident Signal expert at the Boston MRS is convinced that signals would be required for all other possible reverse direction movements. However I seem to think it would depend on what movements are required at spacific locations.

 

Any further advice would be greatfully recived. Perticually as to what route indications the signals on tracks 4 and 5 will require.

 

[Ray H]

I'd suggest that you want an exit signal from roads 1, 2 & 4 - for trains converging onto road 5. None of these signals would need any supplementary provision i.e.  no feathers. You may also want an "advance" signal near the right hand end of road 5 for trains travelling from left to right. You wouldn't be able to approach the exit signals on roads 1 & 2 if a train was travelling from right to left on road 5 nor would you be able to travel from right to left on road 5 [passed any outer signal (at the right hand end)] if a train was moving from left to right towards the exit signal on roads 1 & 2,

 

A further signal would be required on road 6 to protect the double slip and one before that to provide an overlap. The signal nearest the double slip on road 6 would need to be able to route trains onto roads 3 & 4. Similar signalling would need to be provided on road 5 (including route indication for roads 3 & 4), although the outer signal is only required as indicated above.

 

Hope that helps.

[Edwin_m]

The signal on track 5 for right to left movements would require two left hand junction indicators reading to routes 3 and 4, one of which would be lit whenever the signal was cleared.  Even though there is no route straight ahead, after the Foxhall Junction derailment in 1968ish route indicators are provided as described because of the risk of the driver seeing a route ahead and not realising his train has to take a crossover.  The adjacent signal for right to left moves on track 6 would have only one junction indicator for the left-hand divergence into track 4, being cleared with no indicator if the route is to track 3. 

 

As stated, the signal on route 4 for moves left to right would not have any indicator because only one route is available and there is no track continuing straight-ahead. 

[LNERandBR]

 Hi Ray and Edwin

 

Thanks for your reply's. It's very much appreciated.

 

So basically what's required is as below:

 

 

It also looks like I got track 5 and 6 mixed up in my original post so apologies for that however you both seem to have understood what I was trying to say.

 

The only other thing I need to clarify is a question regarding bridges. Basically shortly to the right of the pointwork there is a small viaduct. (as now shown on the trackplan). The general opinion coming out of the club is the signals required for track's 5 and 6 would be positioned before this bridge so that any train stood at them would not be on the bridge.

However Ray's post seems to imply that trains would not be held at these signals. Therefore is the above advice correct or not?

[beast66606]

Your 2-aspect signals should be three.

 

You can do either for signals holding trains on viaducts, both examples exist.

 

I wouldn't worry about overlaps and clearance too much, your model would be very limited, and probably have no signals visible.

[Edwin_m]

If the signal on track 6 has a yellow aspect then the next signal ahead for right to left routes on track 3 and/or 4 (presumably off scene) must have a red aspect.  Since a red must always be preceded by a yellow* the signal on track 5 needs a yellow as well.  For similar reasons so does the signal on track 4. 

 

It would be normal not to put a signal on a viaduct, because of the risk to the driver climbing down to use the phone or any passengers who might open doors thinking they have arrived at a station.  It's not an absolute, but as far as I can tell from Bing Maps there are no northbound signals on Durham viaduct or the Royal Border Bridge for instance, both of which have stations immediately north of them.  There are however signals on the north end of the Forth Bridge. 

 

If the signals are 200 scale yards back from the junction (shorter distance allowed in some cases where speeds are low, which they would be with a double slip involved) then a train could approach the signal on track 6 while another train was making a conflicting move over the double slip.  If the signal on track 6 was too close to the junction then a train could only approach it with a conflicting move taking place ahead if the previous signal was held at red until the train was nearly up to it.  However there are other circumstances where trains could approach on track 6 with the signal at red, such as if the intended route was blocked by another train beyond the junction.  Similar logic applies to all the other signals, and the ones on adjacent lines for the same direction would normally be next to each other to reduce the risk of driver confusion. 

 

*Or a distant board, which doesn't apply here. 

 

Edit: Beast's post appeared while I was writing this and says much the same thing in fewer words.  I agree selective compression can be applied to overlaps but I think it would look a bit odd if a train came screeching to a halt at the signal on track 6 with another one crossing in front only a coach or two length away. 

[Grovenor]

It would be normal not to put a signal on a viaduct, because of the risk to the driver climbing down to use the phone or any passengers who might open doors thinking they have arrived at a station.  It's not an absolute, but as far as I can tell from Bing Maps there are no northbound signals on Durham viaduct or the Royal Border Bridge for instance, both of which have stations immediately north of them.

The famous one from my younger days was the southbound approach to Wilmslow where the signals did indeed stop trains on the viaduct and it was not unknown for commuters hurrying home to step out onto the parapet. (of course the stepping out could have been apocryphal and just told as a warning, but the stopping location was very real).

Keith

[Gwiwer]

If you regard the "wrong direction" moves 5 - 3 or 4 and 4 - 5 as "main line" moves (which can be defined as routes carrying passenger trains although that is not an absolute definition) then the signalling in post 4 is correct as amneded by using 3-aspect lights in place of two.

 

If those moves are only required for shunting light engines, empty passenger or occasional goods trains and are regarded as shunt moves then the signals on line 4 and 5 can be replaced with position lights.  That on line 5 will still require some for of route indication as it admits trains to both lines 3 and 4.  That can be a miniture feather or possibly an illuminated letter or number.

[Gordon A]

Have I read somewhere that double slips have a quite low speed limit placed on them?

 

Gordon A

Bristol

[Gwiwer]

Normally quite low, yes.  They are a fairly sharp deviation from the straight and with multiple blades and frogs each of which is a potential weak point and a possible source of derailment.  A typical speed might be 20mph on the curves with 50 through the straight though lower limits can be found.

[Edwin_m]

In the period of the OP it would be very unusual to find a double slip with more than 20mph allowed on any route.  In the "colour light signal era" they were used only where unavoidable, which usually meant the approaches to major stations with limited space. Single or double slips were more common at wayside sidings dating from earlier eras but on resignalling the slip would be replaced by standard turnouts if the siding survived. 

[The Stationmaster]

In the period of the OP it would be very unusual to find a double slip with more than 20mph allowed on any route.  In the "colour light signal era" they were used only where unavoidable, which usually meant the approaches to major stations with limited space. Single or double slips were more common at wayside sidings dating from earlier eras but on resignalling the slip would be replaced by standard turnouts if the siding survived. 

Agree - and the slip connection would invariably not form part of a running route but be only a crossover etc at a wayside station.  And things got even worse as speeds rose in the '60s and '70s and even trailing slip connections became more & more difficult to maintain properly, one in the Up Main at Slough was removed for precisely that reason.

[LNERandBR]

Thank you everyone for your help and assistence.

 

I've now made up the shopping list required to signal the layout taking into account the further issues identified following my previous post.

 

I had a sneeking suspician the signals near bridges thing isn't as hard a rule as I was being told. Thanks for the advice on this as well. Theres plenty for me to think about there.