SECTIONAL APPENDIX - Chippenham
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General and History
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The market town of Chippenham in Wiltshire saw the first train arrive at its station in may 31st, 1841, coming from the East. The line being constructed through the town was the Great Western Railway (GWR) main line from London to Bristol, authorized in 1835. The next stage, on towards Bath, opened just a month later, on June 30th 1841.
Another company, the Wilts, Somerset and Weymouth Railway (WS&WR), was authorized to build a route to Weymouth and it opened its section from Thingley Junction, just to the west of Chippenham, to Westbury on September 5th, 1848. The WS&WR became part of the GWR in 1851.
An independent company named the Calne Railway was authorized to build a branch from Chippenham to Calne in 1860 and this line was opened on November 3rd, 1863. This company remained independent until 1892 when it, too, became part of the GWR.
Because of the extention to Westbury, the station was rebuild in 1858. It did not change much thereafter until rationalisation in the 1960's. A goods shed and engine depot were also established. The area was controlled by two signal boxes, at either end of the station.
As in so many areas, the decline came in the 1960's. The engine shed closed in 1964, and the Calne branch saw its last service in 1965 and was lifted soon after. Both signalboxed were closed in 1966.

Chippenham station still exists today, but it now consists of nothing more than the two main running lines, with all sidings, yards and related points having been lifted. The down line has been moved from its original platform to run along the south side of the island platform, more or less where the Middle Siding and the Down Bay platform used to be.
The former GWR main line is still open to traffic, as is the line to Westbury. The latter saw only a token passenger service for many a year, its main importance being for freight and diversionary traffic only. But in 2013 a regular passenger service was reinstated as a new two-hourly service was introduced running between Swindon and Westbury.

Signalling
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The simulation depicts the signalling at Chippenham as it was in the 1950's. There were two signalboxes, the East box, on the Up side near to the junction of the Calne branch, and the West box, just beyond the end of the Down Platform.
Levers for the East box are the original numbers, the levers of the West box have 100 added to the original numbers.

Adaptations
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Some adaptations were required in order to work with PC-Rail.
The Up Siding had two access points, one just after signal 41 and the other just in front of signal 30. Both were unsignalled and the points were manually operated. For the simulation, these two access points are combined into one, switch 68 and signal 69 are added to operate this access point.
Access to the engine shed was from a manual operated switch between signals 16 and 41, defined in the simulation as the Up Siding Loop. The exit from the engine shed was not signalled.
There was some discrepency in the information regarding the two distant signals on the Down Line for the West Box. Some information showed these as to be operated by a single lever (26), others showed it to be operated by two separate levers (26 and 27). For the simulation, the latter option is selected, with lever 127 controlling the advance distant combined with signal 2 of the East Box, and lever 126 controlling the distant combined with signal 6.
Signal "A", the Down Distant signal for East Box, was actually numbered as signal 0.

Track Circuits.
There were only few track circuits in this area, mainly just the actual up and down platforms, and the approaches to the outer and inner home signals (1 - 2, 3 - 4 and 102 - 103).
The track circuits in the simulation are defined just to allow proper operation of the simulation.

Stopping locations for Passenger trains and Freight trains
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Passenger trains will, of course, stop at the platforms in the station, as well as in the Down Bay and Calne Bay. Note, however, that both bay platforms can only be used for departures, there are no routes to either bay platform for arriving trains.
Freight trains will also stop on the Up and Down platform. Apart from this, freight trains may also be scheduled to be held in the Down Refuge Siding.

The main Up and Down platforms as well as both bays are 'allocated' to location Chippenham. To allow timed moves between the station and sidings, most sidings are defined as a separate location, using the siding name as location name. In the table showing the section lengths, these sidings are indicated by (L) following the siding name. Freight trains, light engine and empty stock workings may be timed at these locations.
Some sidings have no platform allocation, these are indicated in the table on section lengths by (NoP) following the siding name. It is not possible to set up timed moves to or from these sidings.

Local instructions
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Reversal and wrong line working.
Neither the Up nor Down platform may be used for reversals except for shunt moves. Wrong line working within the station area is also only allowed for shunt moves.
Permissive working is also not allowed on either Up or Down platform, except for shunt moves through signal 6.

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 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.

Fringe boxes
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East : Langley Crossing, 1m 5ch from Chippenham East box.
Note that Chippenham East Down Distant is combined with the Langley Crossing starter. There was an advance distant for Chippenham East box which was combined with the Langley Crossing home signal, this signal is not shown in the simulation.

West : Thingley Junction, 2m 4ch from Chippenham West box.

Calne Branch : Calne, 5m 15ch from Chippenham East box.
There were two intermediate stations on the Calne branch :
  Stanley Bridge Halt, at 2m 4ch
  Black Dog Halt, at 4m 28 ch

The distance between West and East box was 26 chains.

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.
 
Down Platform : actual platform (sigs 125 and 44)       :  8 units
                between sigs. 125 and 6                 : 15 units
Up Platform                                             :  9 units

Calne Bay                                               :  4 units
Middle Siding (L)                                       :  4 units
Reversal Siding (L)                                     :  2 units

Down Bay                                                :  7 units
Down Siding (L)                                         :  5 units

Down Refuge Siding (L)                                  : 19 units
Up Station Siding (L)                                   : 10 units
Up Platform Siding (at signal 114) (NoP)                :  2 units

Length of sections used for shunt moves :
between sigs. 28 and 54/57                              :  6 units
between sigs. 19 and 6                                  : 15 units

Notes : for bay platforms and dead-end sidings, reduce maximum length by one unit if shunt engine is to be attached to rear of train.

Speed Restrictions
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Main lines                                                : 75 mph
Calne Branch                                              : 30 mph
Calne Bay and Down Bay and access points                  : 15 mph
All other points and sidings                              : 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 Castle Class 7010 "Avondale Castle" aproaching Chippenham on the Up Main in April, 1956.
The prominent signal to the right of the train is signal 122/124 on the Down Bay, the bit of track at bottom right is the Down Main.
The freight wagons in the distance are stabled in the Up Siding.
The picture was obtained through Colour-Rail (www.colourrail.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.
