High Street Kensington
This is another busy location and is where the District and Circle Lines either come together or divide, depending on the direction of travel!
To assist in your orientation of the layout of the station, and the signals to which I refer, the following diagram will be of some assistance. Please click on the image itself if you wish to view the 'full size' version.
In addition to the 'through' roads there are two bay platforms, platforms 3 and 4, which are used as routine reversing points by the District Line.
Platform 3, during the hours of the service, is most frequently used by the D Stock trains operating the High Street Kensington to Olympia shuttle service. As it is adjacent to platform 2, through which trains will pass on their way towards Edgware Road and Baker Street, it is an easy 'cross platform' transfer for passengers wishing to continue their journey in that direction.
Platform 4 is used extensively at the start and towards the finish of traffic by both D and C Stock trains. There are a number of booked D Stock trains in the morning which depart from Ealing Common Depot and then reverse at High Street Kensington to all of the westbound destinations. These use this platform extensively, as well as platform 3. C Stock trains coming into service from Triangle sidings also reverse here to go back via Earls Court to Wimbledon. For those familiar with the line, C Stocks no longer routinely go to Olympia - these timetabled moves came to an end with the introduction of the timetable in September 2002.
Similarly towards the end of traffic there are booked moves for trains either returning to Ealing Broadway to stable in Ealing Common Depot in the case of D Stock trains or, in the case of C Stock trains which are destined for Triangle sidings.
During the day however, this 'spare' platform is used frequently for non-timetabled moves. There are a number of scenarios for this.
In the case of a service difficulties through the city the Controller may decide to 'thin out' the service, rather than have the option of a large volume of trains becoming stalled in tunnels - something that is avoided if at all possible. Generally (though not exclusively) it will be trains booked to go to Tower Hill that will be diverted in this way; they will then remain at High Street Kensington until they are slotted back into the westbound service at Earls Court at a time as close as possible to their scheduled time and then resume their normal working. There are occasions however (for example if the westbound service is disrupted) that the Controller will instruct trains to 'run early' and may divert them from their 'booked' destination to keep a service operating to all destinations.
Similarly, should there be problems between High Street Kensington and Edgware Road or if trains from Wimbledon are running late as a result of problems on the Wimbledon branch, C Stock trains are also reversed here - again the intention is usually for them to be slotted back into the service at their right times, though again on occasions the Controller will instruct trains to 'run early' and possibly be diverted as described above. Although unusual to see C Stock trains heading to Ealing Broadway or Richmond it does happen in such cases.
Another example of the unscheduled use of platform is that, should a train be due for driver changeover and no relieving driver is available, the driver may be instructed to stable the train there. This is usually only done when it is known that a driver will be available within a reasonably short period of time, and it usually D Stocks that are left there - C Stocks would normally be 'put away' in Triangle sidings - obviously a train left there for a protracted period reduces the flexibility that this platform offers. If a D Stock is likely to be out of service for a more extended period it would be stabled on the sidings at Parsons Green.
Why not put a D Stock into Triangle sidings, perhaps you wonder. The answer is that they don't fit - they're too long! For the same reason D Stock trains cannot use the bay road platform at Putney Bridge, but (hopefully) we'll look at this area on another page.
This is the station starter at platform 1 at High Street Kensington. As set the train is being routed to Earls Court - this is what a District Line driver would expect to see. A Circle driver would expect a plain green aspect to indicate he was being routed to Gloucester Road.
However - again in times of disruption - Circle Line trains do occasionally stable in Triangle sidings. The driver would have been warned of this in advance, his train would have been detrained and he would then proceed through the area. Normally he would stay with his train as it's more usual that the move is used to achieve the reversal of the train and it can then go back to Edgware Road where it can be stabled longer term, or perhaps then sent back down to Hammersmith depot.
This, again, is a station starting signal and in itself that doesn't seem particularly remarkable! However, if you notice it's sited against the normal direction of travel - it's a 'wrong road' starter.
This enables trains to reverse back from platform 2 to the 'inner rail' in the case of Circle Line trains, in which case the signal would clear with a plain green aspect, or back to Earls Court (or Triangle sidings) for a District Line train if the route indicator was to be illuminated. A Circle Line train could also accept that signal if stabling in Triangle sidings.
However, because it is a 'coloured light' signal it means that (unless proceeding to Triangle sidings) the train can depart in passenger service. If it were a shunt signal this would not be the case - shunt moves are always carried out without passengers on board the train. There are also mirrors and monitors adjacent to this signal, though not visible here.
(The pictures above were supplied by Phil Wimbush)