Metric Underground

We note the latest contract for the renewal of London Transport’s Underground fleet.

When we travel on London’s Underground, the last thing on our mind is probably the measurement system used to build the trains.

Construction of London’s Underground began in 1859, the world’s first, and opened for business on 10 January 1863. Steam traction was the only technology available to provide motive power, and in the beginning all of the locomotives and carriages came from the Great Western Railway. The railway was, of course, imperial throughout.

London enjoyed another first in 1890 with two ‘ground breaking’ engineering achievements. The City and South London was the first underground railway to use electric traction, and the first that would not run in a covered-over trench just below street level but in tubular tunnels bored deep through London’s clay, well below sewers and gas and water mains. Electric traction, signalling, lighting, lifts and ventilation brought metric to the Underground in a big way, although many Britons, then and now, would not see volts, amps and kWh as metric units.

The Central Line, the first modern tube line, opened on 27 June 1900. The financing of this line, which cost five times as much as the C & S L, heralded the first direct involvement of Americans; they would also play a huge role in the technical development of Underground trains right up to the First World War. A shared measurement system probably helped.

1973 saw new stock for the Piccadilly line, a strange blend of excellence and mediocrity in design, and the swan song of imperial measurements. These trains were refurbished in the mid 1990’s and are now to be replaced:

Much of the rolling stock introduced in the 1970s, having been refurbished at least once, has been withdrawn or is due for replacement, and it will not be too long before examples will be found only in museums. American involvement in the development of the London’s underground railways, so significant a century ago, has all but disappeared.

2 thoughts on “Metric Underground”

  1. Light railways systems in the UK are fully metric. I saw km/h signs on the Tyne and Wear Metro in 1980 (shortly after it opened).

    If you visit you will be able to get the distances and operating specifications of the London Underground for all their lines – all information is in kilometres or km/h.

    Other interesting publications that use metric units throughhout are “Guidance on Tramways” ( and “Application of Highway Legislation to Tramcars” ( – Page 14), both by the Office of Rail Regulation.


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