What the Signals Mean.
Signals at Gilling
The signals on the RSME railway at Gilling are accurately modeled on the practice of the full sized 19th/20th century North Eastern railway. Their scale is 1/8th (1.5" to the foot) to be easily seen and fit comfortably into the landscape with the out-sized drivers. They are not for decoration and must be fully complied with. The signalling system is interlocked with the track circuits and points and is essential protection against derailments and collisions. If you intend to run an engine at the RSME you must have a working knowledge of what follows.
Old Styles of signals
In the first instance trains were controlled only by what the driver could see on the track. As traffic increased and went faster then railway policemen were used at junctions and places of danger. They had flags and later mechanical signal devices which they stood by to operate. When they could operate signals from a central point , a signal box, they were still known as Bobbies. Not all railway companies used the same type of signals. There were early signals with a rotating pole that showed a red circle for danger (stop) but which was not visible when the pole turned 90 degrees. This indicated 'go'
Below is an early GWR target signal with extra arm. By turning the post 90 degrees either the red disc or the white arm was presented to the driver.
The Crossbar type is followed by Martin's L&SWR target signal for a facing point where the position of the disc indicates the status of the two branches. Almost every railway had its own system and below we see some more of the ideas in vogue.
below we see a modern Somersault Signal
You can still see today types of target signals on the Welsh Highland and Ffestiniog Railways
but they are not for us.
North Eastern Signals
The North Eastern railway adopted the '1841 invented' 'Lower Quadrant' semaphore signal seen here below.
Some signals, never N.E., are Upper Quadrant type In both cases, when the semaphore arm is horizontal, the signal indicates 'Danger' or if you like 'Stop'.
The example below shows an upper quadrant semaphore signal; not seen at Gilling
There are many arrangements of signal arms on posts and we explore those seen at Gilling in the sections below. We have some signals just like the 1841 type and many like the double aspect block entry signal above except ours dip to indicate 'go' and do not rise like that one does.
Facing and Reverse Sides of Signals
An important principle in looking at the forest of signals in some places is to recognize those facing and those where you are seeing the reverse side. Only those facing the direction of travel must be obeyed. the others apply to trains going elsewhere. Also as a working guide you expect signals that apply to be found on the left side next to the track you are on, or, over it but this does not apply with certainty everywhere; you have to just know where it does not apply.
In the picture above are shown two identical signal posts, each with two arms. On the left the arms are red and yellow with white and black bands near the free ends. On the right side further away the signal arms are both white with black bands near the free ends. This colour code instantly tells the driver that the red and yellow signals apply in the direction he is going, and that the right hand signal is showing it's reverse side (white) and does not apply to his direction of travel. Note that the right side signal will look exactly the same as the left signal to a driver coming the other way on the right main track. However he will see the white side of our signal on the left. In general this divides all the signals that can be seen at any time roughly half and half to signals that do or could apply and those white ones that definitely do not.
Railways, for 100 years and more, have been managed in 'Block Sections'. The safety principle is that along the main lines and branch lines, clear of stations, only one train may be in a block at a time. Blocks might be several miles in length. Many ideas were tried like letting trains set off at timed intervals but inevitably unexpected situations caused terrible accidents. One train per block is now universal. The picture above shows two signals controlling the entry to a 'Block' or 'Section' of the Down (left) and Up (right) main lines at Gilling. Near stations the Blocks are more complicated and more than one train can be in such blocks under special rules. More on this later.
Multi Aspect Signals
The previous picture also illustrates 'Two or Double Aspect' signalling. The yellow arm with the fishtail indicates the state of the next block entry main red arm. In this case it is set at danger. The train may enter this block but be prepared to stop at the next signal. It indicates that the block following the one about to be entered is occupied by a train ahead on the same line. It is possible, but not certain, that by the time the driver can see the next signal that the block ahead will have cleared so unimpeded progress will be possible. If the next block is still occupied the main red board on it's signal will be at danger and the train must stop. The yellow board is a kind of repeater for the entry red signal of the next block. We do not refer to it as a repeater but call it a distant signal. Invariably (at Gilling) the yellow distant signals are automatically controlled by track circuits. The signalman does not control them. The little white bow tie symbol on the signal post indicates that it is automatic.
Gilling only has two aspect mechanical semaphore signalling on the main lines between stations. The real railways now often have three aspect colour light signalling where the status of the next two block entry signals are indicated by coloured lights. Three aspect semaphores were never used because the overhead in wires and pulleys was unwelcome. (The Gilling Two aspect signals, though mechanical semaphores, are operated electrically by solenoids).
In many places a train is confronted by facing points where the route can split two ways. A common solution to the signalling required is a bracket signal with a platform carrying two signal posts. If the branch is to the right of the main line the rightmost signal post has the arm (board) to control that option. Obviously it is an 'either or' situation' and one arm or the other can be set to 'go' but not both. In this picture the two arms are the same size and height which generally indicates that either route can be considered 'main' and no speed restriction applies.This particular example controls a branch to the left on a main-to-main crossover.
If the branch side of a signal is smaller and or lower than the main arm, the branch is not as main as the straight through road and should be considered requiring a speed restriction. Exactly how much depends on driver experience and route knowledge plus any daily written restrictions applying wherever stated.
Sometimes the signal posts carry more than one signal arm even on brackets. More on this below.
In shunting areas such as marshaling yards, factories and congested areas of tracks round stations beyond the platforms - ground signals are often used. There are non at Gilling. Their appearance is typically of one or several discs seen right with a coloured bar that can either be horizontal or set at say 45 degrees to indicate a route. This one also has lights to show red and green corresponding to the position of the discs for night operation.
Station areas or 'Limits' are more complicated than the simple blocks or sections along a main line. Basic to the layout is a signal to release the train standing at a platform.
This signal at the left is the 'Platform Starter' signal at Gilling station. The loco waiting there may proceed as long as the signal releases it by 'going off' (coming to the go position). However there is a snare hidden here. There are many cases of 'go on whistle' meaning that the driver, who is keyed waiting for his guard to whistle that his train is ready to go, may start in spite of the fact that the starter signal is still at danger. This very engine did that on this signal and was derailed at the crossover just visible in the distance. Another case of 'whistle and go'.
There is an advanced starter signal beyond the crossover just out of site beyond the grass which gives the signalman extended control over a train he has released to go down to reverse over the crossover for any reason.
The entrance to a station is guarded by a 'home signal' which is the entry to the station block. If there is a crossover also controlled by the station 'Home Signal', the signalman needs to be able to stop a train some distance out so that it cannot follow a train ahead into a crossover so there will be an 'Outer Home' signal. These outer defenses enable the signalman to control trains maneuvering beyond the reaches of his station platforms within track branches to goods yards warehouses coaling stations and factories without having main-line traffic barging into his traffic movements.
Pictured above is the Gilling home signal at the entrance to the station proper. The left post controls the Down Main line to the station down platform and the right post controls the crossover, (visible), from the Down to Up main lines. This is what was described above for a bracket signal but what is new here are the small arms below the main arms.
These are 'Calling On' arms that permit a train to enter the station block 'even though there may be a train there already standing at a platform'. Obviously this can only be permitted if the second train proceeds slowly having been 'Called On'. The main board will be at danger so the smaller 'Calling on' board is saying speed restriction and enter carefully be prepared to stop behind a stationary train.
The same thing applies to the crossover which allows 'Wrong Way Running' on the up main line through the station. As long as the train crossing over proceeds quietly it may pass the home signal and enter the platform area of the Up main line even though there may be a train somewhere ahead in that block. Note also the lower position of the right hand post indicating speed restriction.
Gilling has signals like this with calling on arms protecting the platform areas both Up and Down.
Sometimes, in two places at Gilling, a signal may be liable to being hidden by a curve where to have to stop abruptly would be a problem if the signal was revealed late to be at danger. The solution is a repeater some distance before which moves in sync with the signal that may be hidden. Gilling has one on each main line in the station area.
This signal seen above is which is found after departure from the Gilling Down Main platform, carries the repeater for the Down Main 'Advanced Starter' signal which is out of sight here round the curve. It is often obscured by cars parked in the grassy area - top left.
The repeater is the white disc in a black circle with a movable black bar. In this position it shows that the advanced starter signal is set to danger. When that signal 'comes off' to indicate road clear, the black bar rotates 45 degrees anti-clockwise to mimic the signal arm position. Drivers thus know the state of the advanced Starter and are able to avoid a sudden stop if they late discover it to be set to danger.
There is another one, seen above, on the Up main line indicating the state of the platform starter signal which is, from this viewpoint, out of sight round the corner of the Village Hall building. This signal offers the same early warning of the 'up platform' starter signal state to avoid a hasty stop.
Note that both of these repeater signals happen to be attached to bracket signals which are facing the wrong way for the lines they are beside. This is merely convenience because the bracket signals happen to be in the right place to mount the repeaters. There is no significance other than that and the signal arms of both these bracket signals do not apply to a train moving in the direction that the repeaters are for.
The signals are interlocked with the track and points. Either the signals are directly operated by track circuits or they are operated by a signalman but within a framework of interlocks with point blade positions. Both 30 lever signal boxes have a mechanical interlock frame that ensures that signals cannot be made to indicate that it is safe to proceed unless the point blades occupy the correct positions to set a route. The power operated points have pneumatic or electric sensors which must indicate a safe, fully home, position before the signal can be pulled to the 'off' position. This is essential to avoid mistakes where a signal could otherwise be set to 'off' with the points in wrong or half-way positions.
It is still possible to make mistakes. The drivers can drive through a signal set at danger; a case of a SPAD - 'Signal Passed at Danger'. The signals after all do not stop the trains, the drivers do. On the real railway you might be prosecuted or suspended. At Gilling you will get shouted at. Collisions or derailments are expensive with valuable locos and stock. As for the Signalman, he also can make mistakes. He can alter the signals and pull the points under a train. This has not happened at Gilling but has been seen at other miniature railways. In short signals and interlocks do not prevent all possible mistakes. You have to remain sharp.
Signals in goods yards
The signal boxes do not control all the points in the goods yards. (3 yards at Gilling). They control entry to the stock shunting track arrays but the points within the shunting arrays are operated by staff on the ground via foot levers. All the signals at entry and exit to the yards are controlled by the signal boxes. Some of the signals differ a bit from what is described so far. We use the Erimus yard to illustrate two differences.
This view seen above is looking West at Erimus yard. The Up and Down Main lines are seen at the left of the picture. There is a bracket signal in the background that controls access to the Erimus yard via a point actually under the diesel seen on the down main.
The track to the right of the down main is the outer Erimus loop and the next right is the inner Erimus loop; two long tracks that can hold trains arriving or making ready to depart. The steam loco is on the signal box controlled branch to the shunting array. Above that steam engine is a signal gantry with three posts; one above each of the described tracks - outer loop, inner loop and shunting array.
Looking west in this picture we see the signals have their red faces towards us and hence control traffic going West. They all also have calling on arms so can also indicate that a limited distance shunting movement is permitted but not unlimited progress out of the Erimus yard limits. We see the steam loco advancing under the calling on signal out of the shunting array towards the limit of shunt.
Seen in the distance between the drivers is a small single post with three arms. We are looking at the white reverse side of it so it only apples to traffic coming towards us. This is where a further principle apples to signals on one post which control branches. The NE system is that the highest one applies to the left most branch. lower ones sequentially apply to a center and then a right branch. right now they are all set against any traffic from the west towards us.
This single post system is seen again below on the exit (out of the bottom of the picture at the right) from the Up Goods Yard controlling access to the up main line(right) and the shed (left). A single post carries two arms one above the other. Applying the NE - highest is left etc rule, the top board indicates permission to take the left curving road to the loco shed. The lower board controls access to the Up Main seen here entering from the right. The post is in the default position, once more, at left of the track. The track at the far left side is not signaled and is used at the discretion of the up yard or shed masters without need of the signalman.
Mix of Block and Route Signals
The two bracket signals seen above and below are the West and East main-line approaches to the Erimus yard. The high arms are the entry control to the main line block/section past Erimus. These signals protect the two 'main to main' crossovers for traffic entering or leaving Erimus. The small posts in each case on the Erimus side of each respective main line are not like the double Home signals on the Gilling station down main. The lower one is not a calling-on signal.
The small signal post indicates the destination, over the same set of initial points, i.e. the 'main to main' crossover and the Erimus branch (clearly seen left). The train is either directed to the Erimus 'Outer Loop' or 'Inner Loop'. Viewed from the West, (top picture), on the Down Main, the small top arm means the left most 'Inner Loop' and the lower arm the right most 'Outer Loop'.
Viewed from the East side of Erimus, (bottom picture) The block entry high arm for the Up main is the same. The smaller post now indicates the Erimus 'Outer Loop' (on our left from this viewpoint) with the upper small arm. The 'Inner Loop' is indicated by the low small arm.
It is not until the train has passed over 3 points into Erimus that the choice of Outer or Inner Loop is selected by the fourth point encountered. Most of the other signals at Gilling control what will happen at the very next point encountered. This case is quite different for these small arms. Note also the lower height and smaller size of the boards on the small post is indicating the the branch is not a main route and that a speed restriction applies.
Wrong Way Working
In a few places, mainly in the Gilling station area, signals are placed apparently with their reverse sides to the normal traffic on each main line. They are for regularly needed train movements used by the signalman where a train might run in say the Down direction through the station Up main line having crossed over at the Gilling Down Home signal. In this case, among others, signals are needed to face the direction of the 'wrong way' traffic to control an exit or a further crossover.
The maneuver just described would be controlled by the bracket signal seen picture-right on the right side of the Up main, (exiting the right-bottom of the picture), at the top left corner of the patch of grass. This bracket signal is showing it's reverse side to the Up main line and has no control over UP traffic. The signal is there purely for 'Wrong Way' traffic on the Station UP main line. Note that in this case the signal is on the right of the track and breaks the default left of track location rule.
There are other examples at Gilling and these are instances of needing the necessary railway route knowledge.
Finally, it is important to realize that just by following the principles set out above you cannot be certain to understand all the signals either on a real N.E. railway or at Gilling. This is because the special positioning and meaning of signals in connection with a local track layout varies from place to place. Signals might be on the left of the track, over it or even on the wrong side. Some, you have a hard time to guess the significance of. You may have to pick out your signals from a thicket of signal posts. In short you need actual route knowledge. No full size railway driver would be allowed to drive a route without completely learning the route first under supervision and remembering by heart where each signal was and what exactly it means in detail. The same is true at Gilling. If you understand what is set out above you will be 2/3rs of the way to understanding the signals at Gilling. Quite a few point-sets operate together as a switchable single entity. The signals are interlocked to protect these ganged points functions. it is helpful to know which they are and what they do.
To understand them all you have to walk the track with someone from Gilling who knows the whole thing by heart who can point out where all the signals are and exactly what they mean.