Jump to content
NIR

Generic Signalling

Rate this topic

Recommended Posts

Posted (edited)

Signalling discussions often get bogged down in talk of blocks, bell codes, homes and distants as if actually operating ten miles of busy mainline.

So, keeping it relevant, what is the minimum signalling required for a layout to be prototypical?

Is it as simple as

1. stop signal to indicate diverging routes ahead (can be assumed offscene, if not too far back from the diverging routes)

2. stop signal to start a movement from a terminus/onto a converging route/onto a single line

3. stop ground signal on final exit from sidings/goods loop

4. stop ground signal each direction on a trailing crossover

5. no signals on simple continuing lines (not modelled for long enough for blocks, homes, distants, etc to become relevant)

(everything else can be reduced to the seven elements in bold - a facing crossover is a diverging route, a diamond crossing is a diverging and a converging route, more complex goods yards are two or more sidings/goods loop, level crossings are continuing lines)

So a through station with routes diverging then converging again and a single fan of sidings could require just starters and one ground signal operated from a signal cabin nearby. Or a through station with continuing lines, a single fan of sidings and a trailing crossover could require just three ground signals operated from a nearby ground frame.

Simplest of all a through station with just continuing lines requires no signals at all, though if you model a signal cabin there does need to be a stop signal somewhere nearby as a nod to the homes and distants nonsense.

Edited by NIR
add converging and crossover and continuing and single

Share this post


Link to post
Share on other sites

It would depend on the track plan, NIR, and the use. If it was a busy passenger station, that’s one thing, but a goods yard could be a ground frame only with no signals.

Share this post


Link to post
Share on other sites
Posted (edited)
5 hours ago, jhb171achill said:

It would depend on the track plan, NIR, and the use. If it was a busy passenger station, that’s one thing, but a goods yard could be a ground frame only with no signals.

I'm just seeing if it reduces to some rules of thumb for trackplan and use, coming up with some generic situations like 'diverging route', 'terminus', 'sidings/loop' instead of talking technical terms like 'home' and 'distant' which seem fairly irrelevant. In your examples a busy passenger station is 1 and 2 in my terms, needing lots of splitters and starters, and a goods yard is 3, potentially needing just one ground signal on the final exit.

Edited by NIR

Share this post


Link to post
Share on other sites
Posted (edited)
On 4/10/2019 at 5:54 PM, NIR said:

Simplest of all, a through station with continuing lines requires no signals at all, though if you model a signal cabin or level crossing there does need to be a stop signal each direction somewhere nearby as a nod to the homes and distants nonsense.

So in a nutshell, in a model you need to signal the routes not signal the flows.

Signalling of flows (the blocks, homes and distants stuff) can be mimicked by having proper separation between trains on the layout - by not having them run on each others tails, by not running them right up to a conflicting route simultaneously and by using the late clearance of stop signals to check their speed before they negotiate points.

Edited by NIR

Share this post


Link to post
Share on other sites

Just a thought with continuous lines  a major feature of a few years ago was the level crossing manually controlled with gate protecting signals.  On a simple layout just a level crossing, keepers small house and small holding alongside, a small 2 lever ground frame for the two signals , the closing of gates and clearing of signals to herald the passing of the train  would allow a trainspotting layout.    

With the proliferation of electronics a motorised set of gates and signals such a layout is achievable. but it is the signals that are important to the action.

Yes NIR you signal routes nor flow - but as importantly it is the signals that stop movement- protecting the active route that are required.  Correctly placed shunting signals at yard exit points  and crossovers maketh the layout for me.  Plus now the supply of parts to more effective model rodding will lift a layout more than DCC and lights and sound!

Robert  

 

Share this post


Link to post
Share on other sites
Posted (edited)
On ‎4‎/‎13‎/‎2019 at 8:00 AM, Robert Shrives said:

Just a thought with continuous lines  a major feature of a few years ago was the level crossing manually controlled with gate protecting signals.  On a simple layout just a level crossing, keepers small house and small holding alongside, a small 2 lever ground frame for the two signals , the closing of gates and clearing of signals to herald the passing of the train  would allow a trainspotting layout.    

Yes, if you want to model the usual run of homes and distants you can just drop them in somewhere far away from everything else, maybe at a level crossing or a remote refuge siding.

 

Edited by NIR

Share this post


Link to post
Share on other sites
Posted (edited)

I've been thinking of generic signalling of loops on a single line, crossing being one of the few signalled flows wholly visible on a layout.

1. Bidirectional passing loop - splitting stop signal with arms of equal height before each entry, stop signal before exit at both ends (6 signals with 8 arms!)

2. Up/down passing loop - stop signal before each entry reading only to one side, stop signal before exit at opposite ends (4 signals with 4 arms, trap points before each exit at opposite ends allow running straight into the loop but this may be deprecated for passenger working)

3. Non-passenger passing loop - splitting stop signal before each entry with lower arm reading to dedicated goods-only line (or stop signal plus ground signal reading to dedicated goods-only line), trap points at both ends of dedicated goods-only line, stop signal (or ground signal) before exiting dedicated goods-only line at both ends (4 signals with 6 arms or 2 signals with 2 arms)

4. Non-passenger passing loop (ground frame only) - as 3 above but no stop signals just ground signals, non-passenger trains 'shut in' on dedicated goods-only line by token

All signals are placed at the toe of the entry point or before the fouling point at the exit (or at toe of trap point if fitted). For 1 and 2 non-crossing trains run straight through but crossing trains are both brought to a halt at the signal controlling entry to the loop before each pulling forward into the loop (except see 2 above). For 3 and 4 non-crossing trains run straight through the non-goods line but for crossing trains the non-passenger train is slowed/stopped at the entry signal then runs onto the goods-only line, the crossing train then runs straight through, two passenger trains can not cross here.

Edited by NIR

Share this post


Link to post
Share on other sites
Posted (edited)

I've also been thinking about shunting on a single line, shunting being another of the few signalled flows wholly visible on a layout.

Generally speaking, shunting can take place freely within the 'station limits' between the home (the first signal) and the starter (the last signal) in each direction of a single signal cabin. The position of these signals rarely coincide in each direction, which is not a problem on double lines but on single lines creates two different 'station limits' on the one line.

H>>>>>>>>>>S
          S<<<<<<<<<<H

The simple but hard to find answer is that, on a single line, shunting can take place freely between the home signals in each direction of a single signal cabin (from H to H above). Which makes sense, this is the furthest extent a signalman can be sure of denying entry - his starters, even if lying beyond the homes in the opposite direction, are irrelevant to oncoming trains as they are facing the other way.

There are no 'shunt limits' on a single line, that concept only applies when shunting wrongway on a double line. On a single line a shunting movement can go as far as is necessary to clear the points and set back, even beyond the home signal if the next signalman is made aware of when the movement begins and ends or if the movement follows in the wake of a train departing in that direction.

So it's something you don't need to give a lot of thought to. You can shunt a single line however you like so long as you set the signalling to stop and keep oncoming movements from either direction off-layout until the shunt is finished. But this is the one time you can properly chase a departing train!

Edited by NIR

Share this post


Link to post
Share on other sites

Though it might be useful to draw up some examples based on traditional mechanical signalling practice in Ireland and the UK. Power signal operation is a totally different kettle of fish and is based on totally different principals, though multi aspect automatic signalling is probably the way to go to squeeze in a lot of train on a layout.

Typical semaphore signalling on a small double line station with a small yard and crossovers for running round a train or shunting.

The first example was typical of smaller stations on the Dublin-Belfast Line and South Eastern suburban before the end of goods services to small stations. Movements from the main line to the siding were controlled by hand signal from signal man to train crew, if it was necessary to pass the Limit of Shunt board the signal man would have to get clearance form the box in advance.

The second example is a larger/busier station intermediate terminus where the running lines were likely to be blocked for prolonged periods while shunting was taking place. Additional signals are provided to allow a train to approach the signal interlocking (station or yard area controlled by signal box) while a train is stopped or shunting on the running line between the arrival (home) and departure (starting) signals. The distance between the caution (distant) and stop (home) signals are based on maximum line speed or upwards of 1/2 mile during steam operation, a challenging proposition for a modeler with restricted space.

436674091_Typicalsmallsuburbanstation.thumb.jpg.0306e8420d54b79fafa17b307c0ce369.jpg

 

A terminal is probably a more manageable proposition than a through station for a manager with a restricted space and more interesting from an operating perspective.

The suburban terminus is a kind of cross between Bangor, Cobh and Harcourt Street (though the latter had only one platform & was modernised with power signalling in the 1930s.

To save space and to be difficult platform 3 is signaled for departures only, though a lot of shunting would have taken place when these lines were operated by steam traction & trains arrived and departed from separate platforms.

I chose Ballinrobe as an example of how large a country branch terminus could be and how little signalling was required compared to a city terminus or a through station, apart from the crossover from the main line to the loop and main line to goods shed road all points were controlled by hand, two discs and two signal arms controlled all movements in and out of the station.

 

Terminus.thumb.jpg.28649513a04ed9d9c04a97f00f479701.jpg

 

I will draw up a couple of examples of single track main line stations, mainly to capture the changes in signalling practice that arose when the railways introduced bi directional running at crossing loops on single lines and went over to Liner Train operation in the 1970s

  • Like 2
  • Informative 2

Share this post


Link to post
Share on other sites

Ballymoe on the Mayo Line & Abbeydorney on the Limerick-Tralee line two examples of signalling of small stations on single track secondary main lines. 

The Mayo Line is more main line in character than the North Kerry with relatively heavy passenger and goods traffic between Dublin and the principal towns in Mayo & Roscommon, while traffic on the North Kerry was traditionally more local in nature through Dublin-Tralee goods and passenger traffic was mainly routed by Mallow and Killarney.

 

Ballymoe was a small station and crossing place between Roscommon and Castlerea on the Athlone-Westport line, the station closed to passenger traffic along with other smaller stations on the Midland in 1963 but continued to handle cattle traffic into the early 1970s the signal cabin and loop closing following the introduction of Liner Train operation on the Mayo Line in the late 1970s. While the majority of passenger trains called at Ballymoe the Ballina Goods did not call  at the smaller stations between Athlone and Manulla Junction and ran non-stop through Ballymoe, in Midland Days the prestigious Up and Down Limited Mail (Day mail) also ran non-stop through Ballymoe during the 1890s

Ballymoe.thumb.jpg.c329704ab6d33c0c4798ee7ed3206ea5.jpg

Signalling:

1. The track is aligned for non-stop running along the main platform road (Up Line) with both platform roads signaled for bi-directional or "Double Way" running, similar in principal to the Dublin-Galway main line, Rosslare Strand-Mallow and Ballymena-Derry on the NCC. 

2. The distant or fishtail signals are fixed at caution as all trains are required to stop or slow to 35mph? for manual staff exchange.

3. The "Mother & Child" home signals are fitted with a second arm on a bracket at lower level (loop home) which controlled access to the passing loop

4. The height of signal posts & arms vary to assist drivers sighting signals.

The down home signal at the Athone end of the station is on a tall post to assist drivers sighting from a distance, while the loop home is mounted at cab level, the up main and loop starting signals at the Athlone end of the station are on short posts to assist sighting through the road overbridge, the down loop starter is on a shorter post than the down main starting signal possibly to reduce the risk of a driver of a non stop train confusing the two signals.

5. A disc controls access from the headshunt to the loop.

6. Movements from the loop to the head shunt may have been controlled by flag signal rather than lowering the starter. It was usually necessary to obtain authorisation (The ETS) to enter the next section in order to lower a starting signal on a single line on the CIE system.

7. All signal posts appeared to be wooden of GSR origin.

Mechanical staff exchange was not installed on the Mayo Line unlike the Galway, Mallow-Rosslare and NCC main line.

The laybye/headshunt allows a signalman to set up a crossing with a goods train that is longer than the crossing loop or to shunt a goods train clear of the running lines to allow two passenger trains to cross.

 

Abbeydorney.thumb.jpg.df03153fee4a9106a7fb7d3c1f1790b5.jpg

Abbeydorney was a small passing station with a single platform, small goods yard and loop for crossing goods trains on the Limerick to Tralee Line. Traffic was lighter than on the Mayo Line with one passenger and one goods train in each direction in CIE days, passenger services ceased in 1963 goods service was gradually run down and withdrawn on the North Kerry during the 1970s. Tralee to Abbeydorney was the last section of the "North Kerry" to remain open for seasonal sugar beet traffic after general goods traffic ceased between Tralee & Listowel. Sugar beet loading facilities appear to have been upgraded at some stage with a high ramp possibly for front end loader or loading shovel operation from sleeper built storage bins placed on the opposite side of the driveway to the railway. Loading would have involved considerable shunting as ramp was only long enough to load one wagon at at time, the yard also received beet pulp in vans. In its final years sugar beet from Abbeydorney, Ardfert and Fenit appears to have been worked in daytime trip workings from Tralee which were re-marshaled into overnight workings to the Tuam sugar factory.

Signalling: 

1. Distant signals are fixed at caution.

2. Home signals fitted with a second arm on a bracket at lower level which controlled access to the goods loop.

3. Exit from the goods loop controlled by ground disc, (vertically revolving disc possibly of WLWR origin)

4. Exit from the goods loop protected by trap points.

5. Level crossing gates controlled by hand

6. Exit from the goods yard to the main line controlled by a shunting disc mounted on a standard signal post on the opposite side of the driveway to the siding.

7. Signals a mixture of wooden and tubular post signals.

 

 

  • Like 2

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...

Important Information

Terms of Use