Transport for London design standards, including the Basic elements standard.

TfL publishes a suite of more than twenty design standards covering its visual identity and its customer environment. TfL says they are for staff, suppliers and design agencies involved in graphic design and layout. Signage-related standards in the suite include the Basic elements, Colour, Pictogram, Interchange signs, Supplementary signs, Door signs in the customer environment, Safety and supplementary notices, Gateline graphics, Line diagram and Text legibility standards.

The Basic elements standard, Issue 8, is the foundation. It covers the corporate typeface, typographic policy, roundels, TfL logotypes, the mark, the Mayor of London logotype and the corporate colours.

The typographic policy is the part every wayfinding designer should know. Set in mixed case, range left, never justify, avoid italics and emphasise with weight instead, keep text horizontal, and never reduce leading or adjust tracking. Minimum type sizes depend on viewing distance. These rules line up closely with BS 8300-2 and the Sign Design Guide, so a scheme designed properly to those will need little rework to meet TfL's.

The roundel rules are strict. The roundel must not be redrawn or modified, must keep its exclusion zone, and must not be reproduced below 12 mm wide where it contains a mode name in the bar.

TfL's standards are a client specification, like Network Rail's Wayfinding Design Manual for national rail stations and the HSE Signage Manual for Irish hospitals. They sit on top of the Building Regulations, BS 8300-2 and the safety signs rules. On the street, Legible London and road signage follow their own systems, and highway signs remain under TSRGD 2016.