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SimSig Wembley Suburban
Official Files
Start-Up Options
Other Options
Operating Notes
Watford Junction
Croxley Green Branch
Wembley Central
Stonebridge Park
Willesden Junction
Queens Park
Fringe Working
Timetable Notes
2006 Timetable
Train Service
Main Movements
Multiplayer & Chaining
Reference Section
Signal Number Plan
Signal Box Prefix Codes
Platform Lengths
Timetabling Details
Line Speeds
Splash Screens
Version History

SimSig Wembley Suburban

Official Files

Title Version Released
Simulation (Donationware) 2.1 12/12/2014
Summer 2006 WTT 1.0 29/10/2019

Additional user-written timetables are available to download here .


Wembley Suburban has been written at the request of the manager of the real Wembley Suburban PSB and with the aid of detailed signalling diagrams. It should, therefore, be as accurate as practical.

The area covered by SimSig Wembley Suburban follows the DC Lines (sometimes called the "New Lines") from Watford Junction south to just north of Camden Junction, where control passes to Wembley Mainline signalling centre. At Watford Junction there are connections to the main (AC) lines, and at Willesden Junction there is a branch to meet the North London Line at Kensal Green Junction. In the Croxley era, at Watford High Street there is a single-track branch to Croxley Green and Cardiff Road CEGB sidings.

The entire simulation (almost) fits into a single screen. It is divided into three "stripes". The boundaries between the stripes are protected by automatic signals, so it is never necessary to consider two stripes at once when handling trains. On all three stripes, the Up direction (south east, towards Euston) is rightwards while the Down direction (north west, towards Watford) is leftwards.

Note that the feature that makes headcodes in sticky notes clickable to bring up the corresponding timetable doesn't work for LU headcodes.

Scale map of simulation area


This version was written with access to official signalling plans giving track layouts, track circuit details, locations, overlap lengths, and gradients. Therefore all of these details are accurate. Note, in particular, that not all automatic signals have "passable" plates in real life and this is replicated on the simulation. Speed limits are taken from the Sectional Appendix. However, in some places train describer berths are merely "plausible" and have not been confirmed.

In general the simulation replicates the situation as of 2007, though with the option to have the extended platform 2 at Willesden Junction (note that when the platform was extended, signal 18 moved to the other side of the track). There is also the option to switch to the layout with the Croxley Green branch, before control was moved from the separate signal box to a workstation within Willesden signalling centre. Note that there were significant changes elsewhere in the controlled area at this time, so enabling the branch has other effects as well. In this manual these differences are described in terms of the "Croxley era" or the "modern era".

Even though "Queen's Park" would be more accurate, the name "Queens Park" is used in the simulation and this manual as it is what is found on the actual workstation and in various documents.

Legal Stuff

SimSig is for personal entertainment use only and must not be used for any commercial use, including the training of signallers etc. Those who are interesting in the commercial application of this software should look at

SimSig is protected by copyright. No SimSig file may be distribution by any other website, by CD ROM or other media without express written permission from G. Mayo. The only exception is when SimSig files are transferred between private individuals where no charge, fee or profit is levied.

This software and is offered as-is, "what-you-see-is-what-you-get". Errors, omissions, faults or other problems are not covered by any warranty of any kind. Problem reports may be emailed or posted on the forums but action may or may not be taken by the authors, a decision which is up to said authors. SimSig accept no responsibility for any damage that may be caused to computer systems by the software.

Start-Up Options


A set of 'line closed' scenarios are available; all will require you to regulate train services around the specified closure. The Willesden Bay and Harrow Siding closures will require timetables to be edited on the fly, unless the timetable was written with the closure in mind.


Default era

By default, the simulation represents the area as it was in 2007, following the closure of Willesden Suburban 'box and its transfer to a separate panel in Wembley Mainline.

Croxley Green

This era simulates the area as it was with the branch to Croxley Green still open. The line in question ceased to receive a service from 1996 (with only a single daily train for 3 years prior to that), and formally closed in 2003.

The Croxley Green branch was removed from the signalling at the same time that the existing interlocking was replaced by a new electronic one. The opportunity was taken to make a number of other changes at the same time.

  • Some signals in the Watford High Street area are controlled in the Croxley era but automatic in the modern era.
  • Some track circuit boundaries were moved.
  • Some automatic signals have R buttons in the modern era but not the Croxley era.
  • Some automatic signals have a "passable" plate in the Croxley era but not the modern era.
  • The signals in the Wembley Central area are semi-automatic in the Croxley era and controlled in the modern era.
  • Some shunt routes do not have overlaps in the Croxley era.
  • Signal 318 in the modern era is an unnumbered "limit of shunt" in the Croxley era.

Lengthened Willesden bay

Willesden Junction platform 2 was lengthened from 67m to 87m prior to the introduction of the Class 378 units in 2009.

Other Options

Scale of problems: Select the level of delay and trackside equipment failures from the drop-down box.

S8 has auto button: Sources differ as to whethe or not signal 8 is provided with an auto button; as no firm conclusion could be reached, the user has the option of enabling or disabling it.

Route to Bakerloo controlled by train describer: Tick to enable the check (present in real life) that an LUL description is present in signal 8's berth before signal 8 will clear.

Routes to Stonebridge Park Depot: Select if the correct train description, any LUL train description, or any train description is required for the Stonebridge Park depot controller to allow a train to enter.

Operating Notes


As is obvious from the name, the entire DC lines are equipped with 750V DC third rail. In addition, that part of the line used by London Underground trains is also equipped with fourth rail DC. At Harrow and Wealdstone, the fourth rail extends into the reversing siding and also along the Down Line (but not the Up Line) to a point level with its end. South of Queens Park, both tracks as far as the crossover, and then the Up Line platform at Kilburn High Road, have fourth rails. Stonebridge Park depot and the Bakerloo Line tracks at Queens Park are only equipped for fourth-rail trains; they cannot be used by third-rail EMUs.

At Watford Junction DC extends along the link to the Down Fast and thence to a point in platform 6 about 80 metres beyond signal WJ2006. The two main lines, but not the sidings or the link, are equipped with AC overhead.

The branch to Kensal Green Junction contains a changeover section from DC to AC. Thus only diesel trains and dual-equipped stock (such as class 313) can use it. The TMD is equipped for third-rail DC.


The signal box special instructions state that routes must not be set from the following signals until TRTS has been given. A penalty will be imposed if this requirement is ignored.

  • Willesden Junction platform 2 starter (18).
  • The exits from Stonebridge Park depot (32 and 34).
  • The exit from Harrow and Wealdstone siding (307).
  • The Watford Junction starting signals (76, 78, 82, and 84).

Watford Junction

At Watford Junction the simulation chains to Simsig Watford Junction, which controls the main lines. Each box sets routes from its area to the other's in the normal way after a slot has been granted. The signals controlled by the other box can only be used for this purpose, and not as the starting point when setting a route. There is also an additional release to allow the crossover between the two boxes (531 points) to be reversed. These points can only be moved if this release or one of the two slots has been granted.

When the two boxes are not chained, sufficient extra lines and signals are displayed to allow trains to be brought in and out of the controlled area. The layout of these lines has been deliberately simplified, though the signals and trackwork used to enter and leave the sidings is accurate. These signals can be controlled in the normal way, though the slots must still be used. Trains can enter on the right hand side on either the Down Fast line (the line through platform 6) or from the Down Slow (not shown) via the Up Fast (the topmost line on the simulation); similarly they can leave to the left on the Down Fast or to the right on the Up Fast. As well as the sidings between the Down Fast and the Up DC, there are further sidings on the far side of the main lines, reached via the Up Fast; these are not shown.

In practice, the signals shown on the main lines are only used to bring trains into and out of service, with platforms 1 to 4 being used the rest of the time. This example should make it clear.


It is early morning. 5X08 needs to enter from Watford Sidings. As per its timetable, set a route from WJ2005 to Platform 6 on the Down Fast line (circled), not forgetting WJ761.


Once 5X08 has arrived at Platform 6, set a route from WJ2006 to 74 ("WATFORD SOUTH (REV.)").


5X08 will stop when it reaches 74 and the driver will change ends. Finally set a route from 309 to Platform 3 (circled). Meanwhile, 5Z02 at WJ759 is about to enter the area, also via Platform 6.


Similarly, at the end of the day, some trains depart Platforms 1-4 for Watford South Reverse, thence Platform 6 and finally the Up Fast line (circled), their destination displayed as "WATFORD DEP. SOUTH".

Croxley Green Branch

The stop board for trains entering Cardiff Road CEGB sidings is located on the middle of the crossover, not at the end of the track circuit. When a train reaches the stop board, it will wait for instructions from the shunter and will then enter without further action from the signaller (unless, of course, there is a train waiting to exit, in which case you have a problem).

Wembley Central

The crossover at Wembley Central is controlled by a ground frame which can be displayed using the "Show" menu. The signaller releases the frame to local control by left-clicking on the "F" button, which will then flash; this will only work if both protecting signals are red and no train is between the signal and the crossover. Releasing the frame will cause two new ground signals to appear (these simulate a handsignaller - there are no signals there in reality). Once the frame has been released, the release lever (number 1) can then be reversed, which will cause the "F" button to light up steadily and unlock the other levers. It is now possible to work the other levers on the lever frame: lever 2 operates the crossover, while levers 3 and 4 operate the signals. To return control to the signaller, lever 1 must be returned to the normal position (which in turn requires the other levers to be normal), which will make the "F" button flash again. The signaller can then right-click on the button.

Stonebridge Park

Stonebridge Park is the access point for the LU depot. Both tracks are bidirectional, though normally 21 Road is used as the arrival line and 22 Road as the departure line. The two tracks then converge into a single one - the signals leading into the depot and the points on the convergence are controlled by the depot signalman and not Wembley Suburban. When a train is signalled towards the depot from Stonebridge Park station, the signal will only clear if there is an LU headcode (see below) beginning 'I' or 'S' in the relevant train describer berth. As an option, the simulation allows this to be turned off or to merely test for any LU headcode. The two yellow lamps are used by the depot staff to indicate which line the next train will appear. Note that they have been known to change their minds or accidentally use the wrong lamp.

Willesden Junction

The bay at Willesden Junction is only 67 metres long (87 metres when lengthened).

Permission must be gained by telephone from Willesden TMD before sending a train there. Failure to get permission will be penalized. Willesden TMD will telephone for permission to enter a train. The signal box special instructions require that, before giving permission, signals 302, 16, and 18 must all have reminders applied. Failure to do this will also be penalized. They also require that the reminder on 302 is not removed until the driver has been asked to call back, and has done so, from the next red signal or from Willesden Junction platform 2. However, at present this is not enforced by the simulation.

Queens Park

Signal 8 will only clear for trains on to the Bakerloo Line if there is an LU headcode (see below) in the train describer berth (there is an option to remove this check) and they have fourth-rail power (there is a negative shoe detector approaching the signal - this cannot be overridden). Sources vary as to whether signal 8 has an auto button, so this is made an option.

If a train with an LU headcode is signalled towards Kilburn High Road from signal 4 (Queens Park Up line), signal 2 will revert to red and stay so until the train has reversed (more precisely, until signal 7 has been cleared and then the platform is unoccupied).


Whilst the TD berth at signal 8 contains a LU headcode (K227), the train cannot yet be signalled onto the Bakerloo line as it hasn't passed over the negative shoe detector.


K227 has now passed over the negative shoe detector, has been detected as a fourth-rail train, and as shown above you can now set a route for it.


The route can be set from signal 8 to Kilburn at any time as this does not require the use of the negative shoe detector.

If a train with an LU headcode is signalled towards Kilburn High Road from signal 4 (Queens Park Platform 1), signal 2 at the former location will revert to red and stay so until the route is set from signal 7. This is because the fourth rail ends at Kilburn High Road, and so aims to stop an LU train before it runs off the end of the fourth rail.


(In greater detail: By default, signal 2 is clear. 2 is put back to red and held there when either signal 4 is off and train describer berth 4 holds an LU headcode (one beginning with a letter), or signals 8 and 4 are both off, the route is set from 8 to 4, and berth 8 holds an LU headcode. In other words, if an LU headcode is heading for signal 2. This latch is released, allowing 2 to clear again, when signal 7 has cleared to yellow at least once and is red again and track circuit EH (the one between signals 2 and 7) is clear.)

Fringe Working

At any of the 9 places where a train can enter (three at Watford, two at Stonebridge Park Depot, Camden Junction, Queens Park, Kensal Green Junction, and Willesden TMD), the fringe box can be told that the line is blocked by putting a special code into the relevant train describer berth:

BLOK indicates a temporary blockage:

  • Trains at Stonebridge Park Depot will be switched to the other track;
  • Trains on the Down Fast at Watford Junction will be switched to the Up Fast, and vice versa;
  • All other trains will be held until the blockage clears.

SHUT, POSS, *T1*, *T2*, or *T3* indicates a longer closure:

*Trains at Stonebridge Park Depot and Watford Junction (including the sidings) will be delayed until the line re-opens;

*All other approaching trains will be cancelled or turned round before entering the area.

Timetable Notes

2006 Timetable

Train Service

The supplied timetable is based on the workings of August 2006 with some imaginary "seeding" workings added. It runs from 04:30 to 05:30 the following day (shown as 29:30), though the last timetabled move ends at 28:42.

There are a total of 687 schedules in the timetable involving 302 trains entering the simulation and 4 seed trains. The only divides are three of the seed trains; the only joins take place right at the end of the timetable.

I am advised that not even the real signallers can make this timetable run to time.


London Overground

Standard railway descriptions (headcodes) are used for non-LUL trains. The first digit is the class of train. The second character is a letter, which usually denotes the route taken by the train. The remaining two digits simply give each train its own identity.

The only train classes used are 2 (Local Passenger Train) and 5 (Ordinary Empty Coaching Stock).

The route letters found in the timetable are as follows.

  • C Watford to Euston, plus ECS from both sets of sidings at Watford
  • D Euston to Watford, plus ECS to both sets of sidings at Watford
  • L Trains from the DC lines to the North London Line (while most of these exit at Kensal Green Junction, a few exit at Camden Junction)
  • M Trains from the North London Line to the DC lines (while most of these enter at Kensal Green Junction, a few enter at Camden Junction)

London Underground

London Underground trains use a description that has the route letter first followed by the train's 3-digit number, which it retains for the entire day. The class of train is not indicated. As a result, the same headcode will appear several times, as (say) train 223 becomes in sequence J223, K223, J223, K223, H223, S223, and so on. Within the supplied timetable, a suffix is used to distinguish these workings; this suffix always runs from 1 to 9 then A to U omitting I and O, irrespective of the first part of the headcode. For example, train 223 is in sequence J223-1, K223-2, K223-3, J223-4, K223-5, K223-6, H223-7, etc.

The route letters used by LU are as follows (note that some trains in the supplied timetable use the "wrong" letter):

  • A to Elephant & Castle
  • F to Queens Park
  • H to Willesden Junction
  • I to Stonebridge Park
  • J to Harrow & Wealdstone
  • K to Waterloo
  • O to London Road depot (empty)
  • P to Queens Park (empty)
  • S to and from Stonebridge Park Depot (empty)
  • T to Harrow & Wealdstone (empty)
  • W to Kilburn High Road (empty)

Main Movements


Silverlink (now London Overground) run a regular service between Euston and Watford Junction calling at all stations. There are also a few services from Willesden Junction to the North London Line and vice versa, operated by class 313 dual-voltage EMUs, and a few ECS DMUs running to and from the TMD.

London Underground

The Bakerloo Line of London Underground runs a frequent service between Central London and Queens Park, with many trains extending to either Harrow and Wealdstone (usually, but not always, reversing in the siding) or Willesden Junction (and then ECS to and from Stonebridge Park Depot). There are also a number of ECS workings into and out of the depot, and some other odd workings.

Freight Services

There are no freight services in the timetable.

Multiplayer & Chaining

The simulation is busy, though its small size makes it ideal for a beginner.

The simulation chains at the following locations:

Simulation Location
Euston Camden Jn
Watford Junction Watford Junction

The simulation does not currently chain to Wembley Main Line at Camden Jn.


Simulation by: Clive Feather

Summer 2006 WTT by: Clive Feather

As ever, my thanks to Geoff and Mike for teaching me how to write simulations, to all the people who provided information, and to the beta testers.

Reference Section

Signal Number Plan

Wembley Suburban Signal Number Plan

This is an Adobe Acrobat PDF file. If you don't have Adobe Acrobat Reader installed on your computer you can get a free download of the latest version from the Adobe website .

Signal Box Prefix Codes

Code Box
HL Willesden High Level Junction*
WJ Watford Junction*
WM Wembley Main Line*

*Fringe box, signals not controlled in this simulation.

Non-prefixed signals are controlled by Wembley Main Line using the WS prefix (former Willesden Suburban signals).

Platform Lengths

Platform Lengths

* See simulation options
Location Platform Length (m)
Bushey Down 134
Up 146
Carpenders Park All 128
Harlesden All 123
Harrow & Wealdstone 1 121
2 128
Hatch End All 137
Headstone Lane All 128
Kensal Green All 123
Kenton All 121
Kilburn High Road Down 145
Up 164
North Wembley All 123
Queens Park 1 141
4 132
South Hampstead All 123
South Kenton All 121
Stonebridge Park All 125
Watford High Street All 128
Watford Junction All 135
Wembley Central All 127
Willesden Junction 1 125
2 67 OR 87*
3 125

Timetabling Details

Remember to set the 'Metro' or 'Tripcock' speed classes in a train's characteristics if they're intended to run at the higher speed limits.

Line Speeds

The general speed limit over most of the line is 45mph with a few slower sections (such as 40mph through the tunnel south of Wembley Central, or 20mph southbound through Bushey station). However, this only applies to EMU stock fitted with tripcocks. All other passenger stock is limited to 25mph south of Harrow, while freight trains have a limit of 40mph north of Harrow and 15mph south of there. Most crossovers, sidings, and bays are 15mph.

Trains will only run at the higher speeds if either the "Metro" or "Tripcock" speed class is set in the train's timetable. Other speed classes may be set but will be ignored.



Splash Screens

Splash01 A brace of Class 313 EMUs at Watford Junction
Splash02 The north end of Willesden Junction station. The line to the left runs from Harlesden Junction on the WCML (see the Wembley Main Line simulation) to Kensal Green Junction on the North London Line. The line was electrified sometime after this photo was taken.
Splash03 A Bakerloo line train reverses in the siding at Harrow
Splash04 Queens Park on the Camden panel of Wembley Main Line box
Splash05 Queens Park and Willesden Junction on the real workstation
Splash06 A Class 313 and a Bakerloo line train pass at Harrow & Wealdstone.
Splash07 A Bakerloo line train arrives at Stonebridge Park, heading south, photographed from a train waiting at signal 32
Splash08 WS32 at Stonebridge Park

Version History

Version History

Last edited by Steamer on 19/12/2020 at 21:28