SECTIONAL APPENDIX - TONBRIDGE


General and History

In 1836, Parliament passed a law which, among others, granted rights to the South Eastern Railway (first known as South Eastern and Dover Railway) to build a railway line from London to Dover. However, restrictions set by the parliament on building new railways in the London area forced the SER to choose a rather circuitous route. The route was to use the London & Brighton Railway line as far as Redhill, and the SER could build the route from Redhill to Folkestone and on to Dover. It was decided that the SER would take over half of the line between Croydon and Redhill which was being build by the L&BR, and would compensate the L&BR for the cost of building that part of the line. Construction began in 1838. The L&BR opened to Redhill on 12 July 1841. The SER reached Tonbridge (at that time still known as Tunbridge) on 26 May 1842, Ashford on 1 December 1842, Folkestone on 28 June 1843 and Dover on 7 February 1844.
The first station at Tonbridge was build to the east of the present station, at the other side of the road bridge which crosses the railway at this location.
After completion of the main line to Dover, the SER started construction of the line to Hastings, which originated at Tonbridge. The first section, to Tunbridge Wells, opened on 20 September 1845, the line was completed in stages and reached Hastings on 1 February 1852. At first, connection to the Hastings line was through a reversal siding to the east of the station. A direct link was build in 1857.
Relations with the LBSCR (which was formed out of the L&BR in 1845) deteriorated as time went by, and reached such a low point around 1860 that the SER decided to create a new cut-off line, directly linking London to the main line via Chislehurst, Orpington and Sevenoaks. The new line would join the existing line at Tonbridge. This required a new station at Tonbridge, which was moved to the west of the road bridge and which still exists as the present station. The cut-off was completed on 1 May 1868.
The station at Tonbridge had two island platforms. In between were two non-platform through lines, and both platforms had a through line on the inside and a dead-end bay, from the west end, on the outside. The bay on the up side was extended as a through platform, becoming the Up Loop, in 1935.

A number of small and large sidings and yards were build at various locations around the station area. For details see the yard descriptions below. An important loco shed was build in the triangle between the lines to Ashford and Tunbridge Wells.

The main line from London to the Kent Coast was electrified in 1961. For many years, the famous Hastings diesels provided the services on the Hastings line until this line was electrified in 1986. Finally, the line to Redhill was electrified in 1993 as part of a possible diversionary route for Channel Tunnel services.
The "A" box and "B" box were both closed around 1962 as part of the electrification works.                                                                      

All lines in the Tonbridge area are still operational. The station layout has remained the same since the extension of the Up Loop in 1935, but the track layout was changed significantly with electrification. The main marshalling yard to the west of the station is still in use, mainly for PW trains. The Down Branch sidings for storage of passenger stock are also still in use, now known as the Jubilee sidings. The Down Main Sidings are also still in use.

Adaptations

The area was controlled by two boxes, "A" box to the west of the station, and "B" box to the east. The lever numbers for the "A" box are the original numbers. For "B" box, the value 100 has been added to the original numbers.
The track circuit locations and identification are as per drawing. A prefix "A" has been added to the TC's for "A" box, "B" box TC's are prefixed by B.  Note that for the station through lines, the TC's have no prefix as the ident was the same for both boxes.

There were three groundframes in the area.
The main one controlled the western access to the Marshalling Sidings and the Down Branch Sidings. Levers for this groundframe are placed to the left of the box levers and prefixed with "M".
The exits to the Ballast Siding and New Siding, both on the Down Main to the east of the station, were also controlled by groudframes. The levers and shunt location buttons for these locations are placed to the right of the box levers, and are prefixed "B" and "N" respectively.

Adaptation for "A" box : lever 16 operated two signals, on the Down Branch and on the Down Branch Siding exit; the signals were selected through points 15. As the PCRail program does not provide for such logic, a separate lever has been allocated to the signal on the Down Branch Siding, signal 16A.

For further adaptations regarding yards and yard exits, see the description for the yards below.

Local instructions

Platform starters - main line and shunt signals

All platform starters have both main line and shunt signals in the main running direction. The main line signals can only be cleared for trains booked to exit on that particular main line. For this logic to work properly, the signal must be able to identify the train's booked route.
The conditions for this logic are such that the following rules apply for these main signals :

     for trains entering on one of the main lines :
        ? all signals between the train and the platform starter must be cleared;
        ? TES must have been received from the fringe box for this train.

     for trains entering from a yard exit :
        ? all signals between the train and the platform starter must be cleared;
        ? the train must have exited the yard (first TC from yard must be lit).

     for trains originating in the platform :
        ? train must have been described to the headcode for the main line service.

Trying to clear a main signal before these conditions are met will result in the reporting of an operator error.

Reversal and wrong direction working on station road

Reversing is allowed on all station roads without specific requirements. Note that passenger trains can only depart in wrong direction from the Up Through (to Down Main and Down Branch), and Up Platform (to Down Main).
Passenger trains can also depart after reversing from the Down Bay, but to the Up Main only.
Wrong direction working is not allowed for the Down Through and the Up Through.
Wrong direction working is allowed (for shunt moves or freight trains only) on the platform lines. Such wrong direction working requires operation of 'asking' levers. See locking table for full details.
In the simulation, small arrows are displayed along the platform lines for each asking lever if this lever is reversed.
                      
Permissive working

Permissive working is not allowed into any station road from any of the main lines. It is allowed for shunting operations only.

Yards

General info

All yards have short approach sections only, such that trains are already almost at the yard exit signal when they are announced. Therefore, most trains will be reported as stopped at the exit signal. This does not mean the train is being delayed; generally, trains are announced a minute before the booked departure.

Down Main Sidings

The Down Main Siding consisted of two dead-end tracks. These were used to store passenger coaching stock. There were also two short spurs, in opposite direction, which could be reached by reversing in the siding. These spurs were very short and could not be used for full trains but were used only to store spare vans etc.

Marshalling Sidings

The Marshalling Sidings, also known as West Yard, was a large freight yard, consisting of two sets of 8 tracks, one set for each direction. It was build in 1941, as part of a general plan set up by the Southern Railway to divert heavy wartime goods traffic between the east coast and the west away from the London area. The yard was a through yard, connected to the Up Branch and Down Branch at both ends.

The eastern end consisted of two exits. These, however, joined just before points 34, so simultaneous moves on both exits were not possible. Each of the two exits also gave access to short shunt spurs. Exit from the yard to these spurs was controlled by signals, but there were no signals at the spurs itself for movements back into the yard. In the simulation, the exit has been simplified to just one road and the shunt spurs have not been included. At both exits there was a main signal which read to the Down Through and Down Local only, and a disk which read to all other station roads. The main signal also had a theatre box which showed "T" when routed to the Down Through, and "L" when routed to the Down Local. The theatre box was controlled by one lever (23), and the appropriate display was selected through the setting of points 32. As the PCRail program cannot handle such logic, two levers have been allocated to operate the theatre box, 23 for the Down Through and 24 for the Down Local. The theatre box must be set before the main signal (17) can be cleared, but the theatre box is slotted by this signal and therefore will not show until the signal is cleared.
Note that the theatre box was not used in combination with the disk.

At the west end of the yard, the connection to the Up Branch and Down Branch was controlled by a groundframe because of the distance to the box. This exit was shared with the west exit of the Down Branch Sidings. Apart from the connections to the main line, there was also a shunt spur parallel to the main line. As the levers controlling access to this shunt spur could be worked without requiring any action from the signalbox, this spur and its related points and signals has not been included in the simulation.

Down Branch Sidings

The Down Branch Sidings, nowadays also known as the Jubilee Sidings, were used for storage of passenger coaching stock. It consisted of four through tracks.

The eastern exit was quite complex. There was a connection to the Down Branch, which gave access to and from the Down side of the station. There was also a connection to the Up Branch which gave access to the Up side of the station, but this was in opposite direction and required reversing on the main line. These two exits were connected by a single line. Operation of these two exits was set up such that simultaneous entry or exit on both exits was prohibited. If, in fact, the exit points were set such that both exits were set to the main line (both 15 and 22 reverse), it was required that the exit signal was cleared before the entry signal could be pulled off (i.e., with 15 and 22 reverse, clearing 13 required 21 to be clear, and setting a route into the siding via 22 required 16(A) to be clear). As it is not possible to set a path through a yard in the simulation, the restriction on the use of these exits has been defined in a slightly different way. Reversing 15 or 22 is restricted in that reversing 15 requires 22 to be normal, and reversing 22 requires 15 to be normal.

As detailed above, the west exit of these sidings was combined with the west exit of the Marshalling Yard.

The main track from the west exit was connected to the exit to the Up Branch, and this connection was protected by a signal (85). The other tracks branched off between pts. 15 and 22. The layout has been simplified in the sim to just three individual exits, which are linked to the same yard and so trains entering the yard at one entry can leave the yard on any of these three exits. Signal 85 has not been included in the sim.

Up Branch Sidings

The Up Branch Sidings consisted of one through track, and one dead-end track which was accessed from the Up Branch. The sidings were used to store passenger coaching stock. There was a short spur which branched off the dead-end siding near to the end of this siding, but this spur was too short for storage of full trains. Simultaneous use of both yard exits was not allowed.

Coal Sidings

The Coal Sidings was a small two-track yard used for unloading coal. Both tracks were dead-end storage tracks. Access to the two tracks was through a double slip. The station ends of this double slip were manually controlled, selecting access to one of the two tracks. The far ends of the double slip were controlled by lever (1)56, setting access to the station area. In the simulation, this has been simplified to just one exit. The coal siding also gave access to a small loading dock, which was next to the Up Loop. Access to the dock required reversing in the coal siding. The access to the dock was not signalled.
                                   
Up Branch Sidings (Tunbridge)

These sidings, which were used for storage of passenger coaching stock, consisted of two dead-end tracks. A peculiarity of these sidings was that "B" box was build on an open frame over one of these tracks.

Loco Yard

There were two access lines to the loco yard, but both joined the line into the station between points (1)18 and signal (1)20, so only one access line could be used at any one time. Therefore, in the simulation, the access has been reduced to a single line.
The engine shed, which stood in the middle of the site, was a brick-built 6 track shed, of which 4 tracks were through lines. The coal yard was located between the shed and the Ashford lines. The turntable was at the end of a spur next to the Hastings lines. The shed was closed in 1964.
The loco yard could only be accessed through the two Up platform lines, which rather complicated light engine movements through the station.

Up Main Sidings

The Up Main Sidings, also known as East Yard or Long Yard, were the original freight sidings. The main entry to this yard was on the west end where it was connected to the Up Main as well as to the Up Platform and Up Loop. A second access was provided further to the east, this crossed the Up and Down Main lines and connected directly to the Goods Yard. Some tracks in the yard were connected at the far end, but there was no connection at the east end to the main lines. The track from which the exit towards the Goods Yard branched off ran through to the main exit, and the signal protecting this exit, (1)11, also read to the main exit, signal (1)16. The other sidings branched off this connection between these two signals. This would have been too complicated for the simulation and therefore signal (1)11 is set up to control the exit to the Goods Yard only. Here, too, simultaneous moves through both exits was not allowed, this is set up in the simulation by locking restrictions between points (1)13, (1)17 and (1)22.

New Siding

The New Siding was constructed in the 1930's to serve industries at this new estate build outside the town. It consisted of several sidings, mostly dead-end. Access was controlled by a 2-lever groundframe, controlling release and points only. Trains entering or exiting the yard were manually signalled, see notes on shunt locations below. Note that a train which is returning from the New Siding to the station area, needs to be flagged at both this groundframe as well as through the Ballast Siding groundframe.

Ballast Siding

The Ballast Siding was a single dead-end siding with an area where ballast could be stored. Ballast was brought in from Woking and stored here until required for track works in the area. Access was controlled by a 2-lever groundframe, similar as for the New Siding.

Goods Yard

The Goods Yard was a large area with extensive provisions for loading and unloading freight wagons. There was a single through line, between signals (1)32 and (1)15. All loading tracks branched off this single line, with access from the east. The line extended beyond signal (1)15 with access to further loading tracks, again all accessed from the east. All loading tracks were dead-end tracks. As in most other yards, simultaneous moves at both ends was not allowed which is set up in the simulation through locking between points (1)14 and (1)34.

Down Station Siding

The Down Station Siding was a short spur, used for engine movements to and from the Goods Yard, as well as for holding engines required for trains on the Down Local. In the simulation, it has not been set up as a yard but as a siding with its own location, such that timetabled moves can be defined to and from this siding.
Points (1)34, on the exit of the Goods Yard, and (1)35, at the Down Station Siding, were connected, and both signals (1)32 and (1)36 were 'yellow' disks, allowing moves from the Goods Yard to the Down Station Siding and vice versa over this connection without the need for any action from the signalbox. Because such moves are not possible in the simulation, this connection has not been included.                                                    

Shunt locations

At many signalboxes there were a number of locations in the area where trains could reverse for shunt workings, with permission to proceed to reverse provided not by signals but by instruction from the signalman, usually by showing a green flag. At Tonbridge, this applied to trains to and from the Ballast Siding and New Siding. The switches which gave access to these sidings were controlled from groundframes, and trains were signalled to proceed by the guard who worked the groundframe.
Permission for trains to proceed at these locations can be given through a series of buttons, displayed next to the levers. When a button is selected, a green flag is shown at the appropriate groundframe. Available routes from these locations and the related locking details are shown in the locking table. Note that these permissions operate in the same way as for signals, in that when permission is granted, all related switches are locked and other routes which would conflict with the permission are also locked.
As obviously permission can be given to only one train at the time, the buttons relating to shunt locations controlled from the same position are mutually exclusive.

Intermediate Block Signals

On all four main lines, Intermediate Block Signals (IBS) control the section to the next box. The section between the last station signal and the IBS is considered to be a separate block. Therefore, distant signals in the station area only read through the last station signal and not through the IBS, so these distant signals can be cleared even if the IBS is not off. Also, trains need not to be cautioned at the preceding signal if the IBS is still at danger.
All IBS had their own distant signal, which was controlled through the same lever as the IBS itself. The distant signals for the IBS on the Down Main towards Paddock Wood, and on the Down Branch towards Tunbridge Wells were stand-alone signals. The distant signals for the IBS on the Up Main towards Hildenborough, and on the Up Branch towards Penshurst, were combined with and slotted by the last station signals, 60 and 74 respectively.

Intermediate Stations

Lyghe Halt.
This station (note the spelling - nowadays it is spelt as Leigh), on the line to Penshurst, at 2m 42c from Tonbridge, is within the control section of Tonbridge, in both Up and Down directions. TES for trains from Penshurst is received before trains stop at this station, and OOS for Up trains is received after the station stop.

High Brooms.
This station, on the line to Tunbridge Wells, at 3m 28c from Tonbridge, is also within the control section of Tonbridge, but in the Down direction only. For down trains, OOS is received after the station stop. For Up trains, ILC is requested before the train stops at High Brooms, but TES is received after the station stop.

Fringe boxes

Distance to fringe boxes (distances from Tonbridge station) :

Hildenborough         : 2m 42c 
Penshurst             : 4m 15c
Paddock Wood          : 5m 23c
Tunbridge Wells Goods : 3m 72c

General instructions

Rules to caution trains.
For semaphore signalling, the rule (rule 39A) applied that for a sequence of signals which had no intermediate or combined distant signal, if the last signal in this sequence could not be cleared, all preceding signals had to be kept at 'danger' at the approach of the train and could only be cleared if the speed of the train was sufficiently reduced. For the simulation, the speed must be reduced (to about 10 mph on approach). The speed while passing the signal must not exceed 15 mph.
See the locking details for the list of signals and conditions where and when trains must be cautioned. Note that the cautioning does not always apply for shunt moves which are wholly within the station area.

Locking rules.
For locking rules please see locking table.

FPL.
Facing Point Locks (FPL) have been provided where these were installed - see Locking information for details.
FPL's normally stand 'out', i.e. the normal position of these levers is 'reverse', in this position the linked switches are locked. To operate the switch, set the FPL lever to 'normal'. Once the switch is thrown, return the FPL lever to 'reverse'. FPL levers are locked in 'reverse' if a route is set over the switch on which they operate, or when this route is occupied. If an FPL is in 'normal' position, all routes over the related switch are blocked and signals can not be cleared.
Note that if an FPL operates on a switch which is part of a crossover, these rules generally also apply to the other switch of this crossover even if the FPL does not work directly on this switch; some shunt moves are exempt from this rule.

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 past the reversal point up to the next signal.
The 'shunt' command can be issued for a train waiting to depart as issuing this command does not affect 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.
 
If an engine is to be attached to a train, it has to be terminated before it can do so.
If the engine is terminated in the same location as the train to which it is to be attached, it will stop short of this train. After the engine has terminated and is redescribed to a 0Z** number, it can be moved onto the train using the 'proceed' command, and can then be coupled to the train using the 'couple' command.
If the engine is terminated in another location and is moved onto the train while it already has a 0Z** number, it will move up to the train and can then be coupled using the 'couple' command.

Section lengths

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.

Station roads (between signals) :

Down Bay      :  8 units (deduct one unit if engine is to be attached)
Down Local    : 12 units
Down Through  : 14 units
Up Through    : 12 units
Up Local      : 12 units
Up Loop       : 13 units

Siding (between signal and buffer stop) :

Down Station Siding : 2 units

Shunt locations, between signals as indicated :

 74 and  13 : 14 units
 60 and  29 : 27 units
158 and 121 :  4 units (for longer trains, 158 can be cleared)
147 and 120 :  4 units

Speed Restrictions

Main lines to/from Hildenborough, Penshurst and Paddock Wood : 70 mph
Main line to Tunbridge Wells : 40 mph (lower speed to reflect ruling gradient)
Main line from Tunbridge Wells : 60 mph

West approach :
Approach on Down Branch from approx. signal 7 : 50 mph
Approach on Down Main from approx. signal 2   : 50 mph
On Up Main to approx. signal 60               : 50 mph
Up and Down main through switches 29 and 41   : 40 mph
Up and Down branch through switches           : 30 mph

Station :
Up and Down Through                           : 80 mph
Down Bay                                      : 15 mph
Down Local                                    : 40 mph
Up Local                                      : 40 mph
Up Loop                                       : 25 mph

East approach :
Up and Down branch through switches           : 20 mph
Up branch from approx. signal 105             : 30 mph

All other yards, sidings, switches etc.       : 15 to 25 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

The opening picture shows ex-SER class H no. 31177 on the 09:38 auto train to Maidstone West, on 20 April 1957. It also shows the very characteristic tunnel-like passages underneath the station concourse and road bridge.
The picture was obtained through Colour-Rail (www.colourrail.com). 

Acknowledgements

Thanks to PCRail-Test team for their help in testing this simulation, and as ever to John Dennis for providing the basic program for the heritage simulations which, for this simulation, needed some new functions to make it all work properly.





             
