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Marker Lights

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Marker Lights or Headcodes

London Underground used to identify the destination of trains by the arrangement of lights displayed on the leading cab front.  The District Line was the most regular and consistent user but other lines used them too, if less consistently.  This article looks at the positions of the lights and arrangements of codes used on the Underground.  Tubeprune's thanks go to Colin Rosenstiel and Brian Hardy for filling in many of the unknown destinations.  The pre-1934 Metropolitan codes are not available so, if anyone has any more information, Tubeprune would be pleased to hear from them.


Background - Marker Lights - Sub Surface Marker Light Codes - Tube Lines Marker Light Codes

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The use of lamp displays to identify trains has existed since quite early on in the history of railways.  Locomotives used to carry oil-lit lamps on the front arranged in a pattern which identified the type of train, e.g "slow passenger train", "fast goods train" etc.  Some railways carried this further by using white discs in place of lamps during the daylight hours and others by using the display to identify the destination or route of the train.   The District Railway appears to have started this practice in steam traction days and it was continued for electric operations.

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Marker Lights

On the Underground, the headlights of electric trains were always referred to as "marker lights", following the American terminology introduced at the time of electrification in the years 1905 to 1907.   The District was the first line to use the arrangement of lights as codes to identify train destinations.  They began this with the main line electrification of 1905.  The original displays were arranged like those seen on steam locomotives as shown for the 1905 arrangement in Fig. 1 below.  From 1910 onwards, the display was altered on new or rebuilt cars as shown for the various dates of introduction.   Tubeprune's thanks to Colin Rosenstiel for filling in many of the unknown destinations.  There are still a few outstanding so, if anyone has any more information, Tubeprune would be pleased to hear from them.

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Fig.1: Arrangement of District Railway marker light lamps on the fronts of trains, 1905 to 1947.  The normal codes used only 5 lamps.  The sixth, introduced in 1947 on the R Stock, was not normally used in service.  The same system was introduced on the Metropolitan Line after the take-over by London Transport in 1934.

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Sub Surface Line Marker Light Codes

The following diagrams show marker light codes known to have been used by the District and Metropolitan Lines.  The Metropolitan codes were only used after the take-over by London Transport in 1934.  

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Fig. 2: District and Metropolitan Lines marker light codes. 

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Tube Lines Marker Light Codes

Marker lights on tube cars were simply a pair of headlamps until the mid-1920s.  The 1926 Standard Stock was the first to have a set of four lamps on the cab front, presumably with the thought that codes would be used like the District but the large number of destinations on the Northern Line seems to have precluded this.  The 1935 and 1938 Tube Stocks had a five lamp display.  The two types used on the tube lines are shown below in Fig. 3.

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Fig. 3: Tube stock marker light displays.

Codes for tube lines were only introduced in the early 1950s.  Their implementation was slow and sporadic and they were not regularly insisted upon in the way the District did theirs.  They died out within ten years and were never regularly seen after 1962.  The intended codes are listed in the following diagrams.

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Fig. 4:  Central Line marker light codes up to 1963.


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Fig. 5:  Bakerloo Line marker light codes for 1938 Tube Stock.


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Fig. 6:  Northern Line marker light codes for 1938 Tube Stock, kindly supplied by Brian Hardy.  Clive Feather pointed out to Tubeprune that the codes for routes via Bank or via Charing Cross for each destination are the same except that routes via Bank have the centre light on, while the routes via Charing Cross have this light off.


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Fig. 7:  Piccadilly Line marker light codes for Standard Tube Stock.

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