What this document is
In February 2009, Transport for London released what it described as the first digital map of speed limits across the capital's road network. Rather than a map meant for human reading, it was built as a data file that satellite navigation companies could load into their systems so that in-car devices would show drivers the correct legal speed limit on any given road and warn them if they exceeded it.
TfL's road safety unit argued the tool addressed a real gap: many satnav systems of the era relied on outdated or estimated speed data, and TfL estimated that universal use of an accurate map could cut collisions on London's roads by around ten percent.
The original standalone download is no longer hosted at its 2009 web address. TfL now folds speed-limit information into its wider Safe Speeds program and open-data offering, which covers the borough-by-borough rollout of 20mph zones that has continued in the years since the map's original release.
Where to find it
Available from Transport for London.