TfL Ref: 0768-2223
Thank you for your request received by us on 29 June 2022 asking for information about the speed limits of various Transport for London services in metric and imperial measurements.
Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold some of the information you require. You asked:
* which TfL services (i.e, the tube lines, Overground, Tramlink, DLR etc) are fully metric. By "fully metric", I mean speeds (and speed limits) are defined in km/h, as opposed to mph.
* for the ones which are, why they have been made fully metric, and (where applicable) when they were changed from imperial (mph) to metric (km/h).
* for the ones which aren't, why they have not been made fully metric.
London Tramlink
The Tramlink network is ‘fully metric’ with line speeds measured in kilometres an hour (km/h), and was designed and built with a metric system in mind.
We can also advise that the Traffic Signs Regulations and General Directions, UK Statutory Instruments states that tram speed signage should be shown in kph. However, if you would like to know the reasons why, we suggest contacting the Government’s Department for Transport directly.
Docklands Light Railway (DLR)
The DLR operates a metric system and has always done so. Distances are defined in kilometres, with speeds measured in kilometres per hour. Furthermore, the DLR signalling system has always worked with a metric based system.
London Overground
The London Overground network, which shares part of its rail infrastructure with National Rail services, uses an imperial based system. Speeds for London Overground services have always been measured in miles per hour. Therefore, as its overall rail infrastructure and signalling systems are maintained and developed by Network Rail, we advise contacting them directly for further insight.
London Underground
The London Underground network uses a mixture of metric and imperial measuring systems, with some Tube lines using both kph and mph for speed measurements, as listed accordingly below:
Bakerloo: mph
Central: kph
District: mph
Hammersmith and City: mph
Jubilee: mph and kph
Metropolitan: mph
Northern: mph and kph
Piccadilly : mph
Victoria: mph
London Underground services, such as the District and Bakerloo lines share part of their track infrastructure with the National Rail network, which as mentioned previously, uses an imperial based system. From a London Underground track perspective, distances, dimensions and tolerances have been metric for a considerable length of time, with some track components such as bolts being imperial.
Turning to your query, ‘for the ones which are, why they have been made fully metric, and (where applicable) when they were changed from imperial (mph) to metric (km/h).* for the ones which aren't, why they have not been made fully metric’, as you are seeking an explanation, rather than asking for recorded information as required by the Act, we have asked our Customer Services team to respond to you directly.
London Buses
We measure the speed of bus services in miles per hour; an easily understood metric, which is also in accordance with the standard unit for measuring speed in the UK.
If this is not the information you are looking for, or if you are unable to access it for any reason, please do not hesitate to contact me.
Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.
Yours sincerely
Jasmine Howard
FOI Case Officer
FOI Case Management Team
General Counsel
Transport for London
