SECTIONAL APPENDIX - EDINBURGH PRINCES STREET
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General
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The Caledonian Railways Company first reached Edinburgh in 1848, when it completed its main line from Carlisle to Glasgow and Edinburgh via Carstairs. It build its Edinburgh terminal at Lothian Street, near the Western end of Princes Street.
The line was extended a little in 1870 and a new terminal was build at Princes Street itself. Increasing traffic required an extended new station, and a large, 7 platform station was build with the entrance facing Princes Street. A large hotel, known as the Caledionan, was added to the station buildings in 1903.

The station served the two Caledonian main lines to Carlisle via Carstairs, and to Glasgow via Shotts, as well as a number of suburban routes. There were also through trains to Stirling and beyond, which was also part of the Caledonian network, but those trains had to use routes of the North British Railways from Haymarket (West Jn) to Larbert where they would reach Caledonian metals again.

The importance of Princes Street station started to decline after nationalisation. Most of the suburban routes were closed during the 1950's, only the service to Leith (North) survived into the 1960's. It was withdrawn in 1962 as the last of the Caledonian suburban services. Rationalisation of the network led to the inevitable closure of Princes Street station in 1965, with all main line services transfered to Waverley station.

Apart from the Caledonian Hotel which still stands and is still in use as a hotel, no trace remains of Princes Street station or its approaches. The new Western Approach road partly uses the former railway route, and all the remaining site has been turned into parking areas or has been built over by modern office buildings. 

The station had 7 platforms, with platform 1 at the East end of the station.
Next to platform 7 was the Horse Loading Bank. This line and platform 7 gave access to the turntable line, which had the only watercrane in the area, and which led to the turntable. The other end of the turntable could be reached through a switch in the Up Main. There was just a short siding next to the turntable, and there was a single stabling road connected to the turntable itself.
Another short siding was also reached from the Up Main, and was located just in front of the signal box.

A series of carriage sidings was added to the east of the station, next to platform 1. These could be reached through the Through Siding.

Adjacent box
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The adjacent box for Princes Street was Dalry Junction, at 46 chain from Princes Street.
The main engine depot for trains working out of Princes Street was also located at Dalry Junction.

Signalling
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The signalling as detailed in the simulation shows the situation as it was during the 1950's.
The signalling setup was rather unconventional, as detailed below.

Platform starters and pre-starters
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All platforms except platform 1 had pre-starter signals, located just in front of the cross-overs which connected the two adjacent tracks inbetween the platforms.
The actual starter signals were located at the end of the platforms and applied to the lines which were joined after the cross-over, even though the signals themselves were placed well ahead of the actual switch where these lines joined. For instance, signal 17 was the starter signal for both platform 4 and 5 which were routed to the Up Main, but this signal is placed well ahead of the switch (25a) where these lines joined.
In the simulation, the lines at the bottom of the gantries is drawn to all tracks to which the signals apply.
The main starter signals had to be cleared before the pre-starter signals could be drawn off. It was not possible to clear the pre-starter signals and have the train wait at the actual starter.
The main starter signals (for the route to the Up Main) all had an additional calling-on signal for the same route, which could be used to allow light engines to exit from the platform before the departing train had cleared beyond the next signal. This is not possible in the simulation, so these subsidiary signals have no real function here (except for signal 45 which covers a number of routes not available for the main signal).
A special table listing all routes from the platforms and the signals which must be cleared for that route is included in the locking details.

Note that due to this very special placement of these starter signals, these  must not be reset after passage of a train until that train has reached the next track-circuit (i.e. A2, B3, C2 or D3).
Also, any shunt move must reverse at the pre-starter signals and not at the main starters, 'stop at' commands should not be used to stop trains at any of the starter signals.

Approach route indication signals
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The signals on the main approach to the station all had an additional route indication signal (theatre box), showing to which platform the route was cleared. Unlike the more conventional situation, where the route selection also clears the main signal, in this situation there were levers for the route indication signals and separate levers for the actual signal itself, plus an additional lever for a calling-on signal (except on the Up Main).
A full list of all route indication signals is included in the locking details and is shown on the display of the simulation as well.
In the simulation, the route indication signals must be set before the main or calling-on signal can be cleared. Note that the route indication signals will obviously require the proper route to be set, but these signals do not lock the switches in that route - it is the main or subsidiary signal which actually locks the switches.
When resetting the signal, the main or subsidiary signal must be reset first before the route indication signal can be reset.
There was no route indication signal for routes to the Horse Loading Bank, but this route was controlled by a separate shunt arm. For the Up Main, there were two shunt arms, one for the Horse Loading Bank and one for the short Siding, but both were controlled by the same lever (34), such a combination is not possible in the simulation so lever 34 only controls a single signal which applies to both routes.

Signals 23-50-120
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There were three separate levers controlling the three routes to the Up Main : lever 23 for the 'straight' route running from platforms 4-5-6-7, lever 50 for the route coming through cross-over 76/77, and lever 120 for the route from the turntable.
However, these three levers worked on a single signal only. This has been set up like this in the simulation as well. So signal 23/50/120 applies to all three lines converging on switches 121 and 76 even though the signal is placed ahead of these switches. Note that, because of the lack of any overlap, switches 76 and 121 must be properly aligned if any route is set leading upto signal 23/50/120.

Adaptations
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Some adaptations were required in order for this simulation to work with PC-Rail.

Signal 23A was added on the Up Main line, because the simulation requires a single signal as 'block' signal to the next box, and also as limit for shunt actions reversing at signal 41/123.

Signals 119 was a single signal applying to both the line from the turntable and the short siding, but such a combination is not possible so an additional signal has been located at the siding, identified as 119A.

The switch connecting the turntable line and the short siding was manually operated, for the simulation it has been allocated to lever 124.
The two safety switches in the turntable line and the siding were worked by lever 121, but as the position is the reverse of the actual switch 121 in the Up Main, it was necessary to allocate these to a separate lever (125).

It was not clear if the Through Siding did run on to Dalry Junction, nor how it was signalled or how it was used. Therefor, in the simulation it has been reduced to a dead-end shunt spur only.

The track circuits as detailed in the simulation are as close as possible to the actual situation, except that some trackcircuits are extended to cover switches which in reality did not have a track-circuit.

Local instructions
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Locking rules.
For locking rules please see locking table.
Take good notice of these rules as there are many additional flank protection and overlap locks.

FPL.
Facing Point Locks (FPL) have been provided where these were installed - see Locking information for details.
In this simulation, switches are locked with the FPL levers in 'normal' position. To operate the switch, set the FPL lever to 'reverse'. Once the switch is thrown, return the FPL lever to 'normal'. FPL levers are locked in 'normal' if a route is set over the switch on which they operate, or when this route is occupied. If an FPL is in 'reverse' position, all routes over the related switch are blocked and signals can not be cleared.
There are a large number of FPL levers in this simulation, 16 in all, many of which lock more than one switch.
In total, 17 switch levers are locked by FPL. For many cross-overs, the two switches making up the cross-over are locked by two different FPL.
There are two tables in the locking details showing the link between the FPL and switch levers.

Notes on shunting
-----------------

The 'shunt' command must be used if a train is to reverse at a particular signal. It is good practice to issue the shunt command before clearing the last signal which leads to the location where the train is to reverse, this in order to avoid 'overshoot' when the shunt command is issued too late for the engine to brake in time, which will result in the engine running passed the reversal point upto the next signal.
The 'shunt' command can be issued for a train waiting to depart as issuing this command does not effect the timed departure of this train. However, the shunt command must NOT be used for a signal which is beyond a booked station stop before the train has come to a stand for that specific station stop. Setting the shunt command before the train has stopped will cancel out the station stop, and will lead to an error on missed station stop.

Notes on timetable routings
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Various parts of the simulation have been allocated to different 'locations' which allow moves to and from these areas to be defined as timetabled moves.

The separate areas available in this simulation are :

Princes Street Station (this includes all platforms).
Through Siding.
Horse Loading Bank.
Siding (at signal 122).

Section lengths
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The list below details the lengths of platforms and sidings etc.
The length is defined in units, each unit equals an engine, a passenger coach, or 3 wagons.
 
Platform 1 (between buffer stop and signal 47)       : 11
Platform 2 (between buffer stop and signal 43)       :  9
Platform 3 (between buffer stop and signal 42)       :  9
Platform 4 (between buffer stop and signal 16)       :  9
Platform 5 (between buffer stop and signal 15)       :  9
Platform 6 (between buffer stop and signal  6)       :  9
Platform 7 (between buffer stop and signal  5)       :  7
Horse Loading Bank                                   :  6
Siding (between buffer stop and signal 122)          :  2
Up Main line between sigs. 41/123 and 23A            :  5
Down Slow line between sigs. 114 and limit-of-shunt  :  2
Through siding (between signal 115 and buffer stop)  : 15

Speed Restrictions
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Up Main line from signal 23/50/121 onward                 : 25 mph
Down Main line upto switch 77                             : 25 mph
Down Slow line upto signal 114                            : 25 mph
Turntable approaches (both Left and Right)                :  5 mph
All other lines within the area                           : 10 mph

Train Reporting Numbers
-----------------------
Train reporting numbers only came into use in later years, and also changed over the years. See timetable information for details.

Opening Picture
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The opening picture shows 4MT no. 42271 on an unidentified working running into platform 2, on May 8th 1963.
The picture shows, from left to right, platforms 5, 4, 3 and 2.
The pre-starter disks are visible right at the front, with the main starter signals on the gantries at the end of the platform. It is clearly visible that these starter signals are placed well ahead of the switches where the roads from the platforms join.
The signal box is to the left, and beyond is the main exit signal (23/50/120). The yellow light beneath this signal is the distant for Dalry Junction, this distant signal is not shown in the simulation.
Behind the signalbox, between it and the stone wall, is the turntable line with the watercrane. Beyond the wall, lying slightly higher than Princes Street station, is the Lothian Road goods depot.
On the far right, some vans are stabled in the carriage sidings.
The picture was obtained through Colour-Rail, see www.colour-rail.com.

Acknowledgements
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Thanks to PC-Test team for their help in testing this simulation, and as ever to John Dennis for sorting out the very special program requirements for this particular simulation.

