A Railway Controlled by Lego Signals
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Posted 17 August 2010 - 10:19 PM
A particularly interesting way to operate a railway is if the signals are not just decorative, but are actually used to control the trains. This post gives you ideas about how to do this.
For this, the old Lego battery trains are very useful, because they had a mechanism that automatically stopped the train when it came to a signal at "danger". For younger members, let's explain how the mechanism worked. A special component could be fixed underneath a locomotive; it contained a tiny red press switch (in the photo above, the pencil points to the switch). Pressing the switch cuts off the power to the motor. Each Lego signal had a ramp between the rails, so that as the train went past, the switch would strike the ramp and thereby stop the train. Changing the signal to "all clear" would lower the ramp and so the train would restart.
(Collectors may like to know that this signal equipment was shown as set 156 in British Lego guides around 1970).
So how do we make really good use of this feature? First we set up a layout which needs at least two people (or even three) to run it. And remember that a signalman on the real railways cannot see the entire railway system, he can only see the bit that is close to his signal cabin, and so he has to co-operate with other signalmen up and down the line to ensure the trains run safely. So, if possible, set up the Lego railway so that each operator cannot see the entire system, for example like this:-
Since each operator can't see the whole railway, they need to send telegraph messages to each other to run the trains. A simple telegraph system can easily be made from switches, buzzers and wires. (But I'd better admit that the system I'm going to describe is more complicated than absolutely necessary!)
To see how it works, let's take a trip up the line.
We start at the station tucked behind the sofa, shown in the photo above. A freight train is waiting at the signal for the line to be clear. In the background, you can just see the telegraph instruments linked to the next station.
And here is a close up of that telegraph. The next station gives me four buzzes (which means, "Is line clear for an express"?). I reply that it is (by repeating the buzzes), then confirm it by switching on the green light on my telegraph instrument. This also lights a green light on his instrument; it is a continuous reminder to both of us that I have given him permission to send me a train.
Soon he sends me two buzzes (meaning that the train has left his station), so I switch my telegraph instrument to red; this is a continuous reminder to us both that there is a train on the line.
Right, let's start to make our way up the line ...
... aha, here comes that express train!
This express has a feature from the Italian "Settebello" train which, alas, I don't expect ever to see on a British train: passengers have an excellent view from a passenger compartment ahead of the driver's cabin.
In the background, you can see the next station; let's get closer.
Middle station, as we call it, is where the single-track line becomes double-track. The push-pull train is waiting in the reversing siding.
The telegraphs at Middle station look more complicated, because there is a station on both sides of this one, and therefore two instruments. On the right, the red light is on, showing that that express train is still occupying the single line (the upper lights refer to a train going away from us).
But soon the telegraph sounds (two buzzes, a pause, then another buzz), telling us that the express has arrived there, and they switch the red light out, then immediately ask this station if it is okay to send that freight train. This station agrees and switches on the green light (lower lights refer to a train coming towards us.)
The other telegraph communicates with the other station (which we have not yet visited - it's called Hatch station), and although this telegraph looks different from the one we have just seen, the method of using it is the same. But this instrument has two needles, each of which can point to one of three messages ("Train on line"/"Normal"/"Line clear"), which mean exactly the same as "red light"/"no light"/"green light" do. The needles are more realistic than the lights - more like the instruments used in real British signalboxes! The signalman at Hatch has just asked permission to send a parcels train, and in reply the signalman here has set the needle to "Line clear". So we expect trains approaching from both directions!
The buildings around Middle station are the work of my nephew and his friend. The station has two signals, one to control trains on the southbound track, and the other to control trains on the northbound track. At the moment, the signal on the right must be kept at danger, as we cannot allow the approaching parcels train to go past onto the single line, along which (we assume) the freight train is already approaching.
One of the things I like about operating middle station, when I get a chance, is that the operator shouldn't need to touch the trains at all (except for the occasional trains that go into the reversing siding). Just get the signal operation right and the trains will take care of themselves - very like being a real signalman!
Notice that the signal on the left has wires going to it, which makes some people think it is remote controlled. But no, you have to reach over and pull the lever, just like all the other signals here. What the wires operate is a lock.
The lock keeps the signal at "danger", and it can only be released by the signalman at Hatch. The signalman at Middle, as he's already expecting a freight train right now, telegraphs Hatch for permission to send the freight on to Hatch. When, in reply, the signalman at Hatch sets his telegraph instrument to "Line clear", this causes the lock on the signal to change from LOCKED to FREE, so the signalman at Middle can put the signal to clear.
So it is impossible to send a train to Hatch without first getting permission from the signalman there.
The locking system is a home-made modification to the Lego signal. (This signal was already broken in a way that meant it could never be restored to perfect original condition, so I wasn't worried about making my own modifications to it!).
The freight train, which we saw earlier, soon rumbles through, no need to stop, and continues up the line. Let's follow it ...
Now we get our first glimpse of Hatch station. The aforementioned parcels train is just leaving the station.
Incidentally, the parcels train includes a vehicle from set 113 - the very first electric Lego train set, back in the 1960s! When creating their first train set, you might have expected that Lego would start with something as simple as possible ... but no, the set had two big bogie carriages, including this type of postal van. These big vehicles soon disappeared from the catalogues, and by the early 1970s, the trains in the British Lego catalogue consisted entirely of four-wheel vehicles.
And now we get a proper view of Hatch station. The two tracks through the station make it easy for one train to overtake another that needs to wait a while.
The freight train passes the "home" signal that controls trains entering the station, and rounds the end curve, passing over a "treadle" - which is that yellow thing - it's a switch operated by the weight of the train going over it. I'll explain what that's for in a moment, but first let's follow the freight train ...
... as it pulls into one of the station tracks and terminates. Next it will need to shunt the wagons into the siding for unloading, and the locomotive will probably pick up some other wagons.
This is a good place to explain how we operate freight trains. Each freight wagon carries a small rolled-up slip of paper (perhaps you noticed this in earlier photos?). On arrival at either of the end stations, the operator shunts the wagons into a siding or platform for unloading, removes and unrolls the slips of paper, ticks off the journey that has just been completed, and reads off what the wagon has to carry on its next journey. The two end stations are called "Hall" and "Hatch".
Middle station is never the starting or finishing point for wagon journeys; this is because the signalman at Middle has to deal with twice as many telegraph messages as the other two operators, and just doesn't have the time to deal with wagon loading!
Indeed that is one of the main reasons I introduced the wagon loading system; before then, the operators at the ends were liable to get bored, whilst the one in the middle was overworked; it evens things out. Also, some operators used to prefer passenger trains to freight, to such an extent that I sometimes found freight wagons had been removed from the tracks before the end of an operating session. Huh! The wagon label system reversed this, the operators getting so engrossed in despatching their freight that the passenger service went to pot!
The telegraph instrument at Hatch also uses two needles to display messages, although the usual electric switch is replaced by the bit of black Lego near the bottom, which can be rotated. But it has an extra safety feature that the other stations do not have. Once the operator here switches the instrument to "Train on line" (as shown), the instrument is then locked in that position until the train arrives and operates the "treadle" I mentioned three photos back, and the operator has afterwards put the home signal back to danger, all of which releases the lock. Only then can he switch the instument to "Line clear". And until he gives "Line clear", the signal at Middle station is locked at danger (remember that signal with the electric lock on it?).
What this combination of locks means is that it is almost physically impossible to signal one train to crash into the back of another on this section of track. So this section is better protected than other sections of our layout - and better protected than some sections on the real railways of Britain.
Hardcore signalling enthusiasts may like to know that this is based on the Midland Railway's "Rotary Interlocking Block" system.
In this case, immediately after the signalman here telegraphed that the freight train had arrived, the signalman at Middle asked permission to send the push-pull train; the signalman here switched his instrument to "Line clear" (thus releasing the lock of the signal at Middle) ...
... and soon the push-pull train arrived, with the locomotive pushing.
So that concludes our trip up the line. Anyone who wants to try producing their own version should probably start with a simpler system. The red and green lights, needles, treadle and locks are not essential, although they do make it more like "the real thing". But you don't really need more than a simple telegraph system, which can be rigged up from a couple of buzzers, a couple of switches, a battery and some wire. British signalmen don't use Morse code, but have a special code for each message, which is much quicker, as well as being easier to learn ... provided you don't try to learn the entire code, but just the 6 or so messages that you really need.
For anyone wanting to know more about signalling methods on the real railways, the British system (on which my set-up is based) is described on John Hinson's Signalbox website. Calvert describes the American system for controlling single-track railways, which was somewhat different from the British system by the early 20th century. Calvert also provides a great many details about European signalling.
Posted 18 August 2010 - 06:16 PM
This is a really great article/post! I'm less interested in pretty trains running around ovals and more interested in railroad operations, so this fit the bill. I also loved seeing that you were able to achieve such amazing operational possibilities with the vintage 4.5V trains, as I thought these were especially limited to just running around ovals. I loved that the operators were visually seperated too and that the waybill system travels with the cars. Absolutely brilliant and looks like a lot of fun.
It totally motivates me to want to implement a track signalling system on my future layout! Thanks!
It totally motivates me to want to implement a track signalling system on my future layout! Thanks!
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