Department for Transport Guidelines on setting local speed limits
Main points
Speed limits should be evidence-led and self-explaining and seek to
reinforce people’s assessment of what is a safe speed to travel. They
should encourage self-compliance. Speed limits should be seen by
drivers as the maximum rather than a target speed.
Traffic authorities set local speed limits in situations where local needs
and conditions suggest a speed limit that is lower than the national
speed limit.
This guidance should also be used as the basis for assessments of
local speed limits, for developing route management strategies and for
developing the speed management strategies.
Traffic authorities should use the right speed limits in the right
places. They should keep their speed limits under review and only
introduce 20mph limits and zones in the right places, over time and with
local support in urban areas and built-up village streets that are primarily
residential.
You can read the full report HERE