Legislative Requirements

To manage compliance, it is important the limit is signed correctly and consistently. Road authorities must ensure speed limits meet the legislative process and the requirements of the Traffic Sign Regulations General Directions (TSRGD) legislation.

Any new limit should also be accompanied by publicity and communications.

The TSRGD and the Traffic Signs Manual should be used by road authorities to determine the use, placing and positioning of signs.

Implementing 20 mph Speed Limits – Sign Only

20 mph speed limits do not require traffic calming. They are like other local speed limits. The full requirements for the establishment of a 20 mph limit is set out in The Traffic Signs Regulations and General Directions 2016 (legislation.gov.uk) and the Traffic Signs Manual

Repeaters – 20 mph Limit

The TSRGD (2016) removes the requirement for a minimum of one repeater sign to be placed within a 20 mph speed limit. It is for road authorities to determine how many repeater signs are needed and where they should be placed, taking cognisance of the Traffic Signs Manual Chapter 3 ensuring there are sufficient repeater signs placed to inform road users of the speed limit in force.

Point to Note - When lit roads have a speed limit other than 30 mph, repeater signs can assist road users to understand the limit of the road and assist with compliance.

20 mph Zone into a 20 mph Speed Limit

Signs must be provided at each entrance to the zone, even where the adjacent speed limit is 20 mph speed limit (without traffic calming features). The lower panel may be varied or omitted, but the speed limit roundel in the upper panel must not be varied to any other speed limit. Normally only one sign is likely to be needed, particularly where the zone commences in a side road at a junction.

Where the adjacent speed limit is 20 mph adjacent speed limit is 20 mph (without traffic calming features), the sign is replaced by a 20 mph terminal sign.

20 mph Speed Limit - Zones

20 mph zones are different from a 20 mph limit as they require traffic calming. The full requirements for the establishment of a 20 mph zone is set out in detail in the TSRGD and the Traffic Signs Manual .

In Scotland, 20 mph should be the standard speed limit in the vicinity of schools. The actual route to school should also be considered for 20 mph speed limits / zones as very few pupils live on the street the school is located, broadening 20 mph zones or speed limits will enable a safer journey to and from school.

Point to note – Speed cushions / humps encourage the braking and acceleration of vehicles which can lead to an increase in noise nuisance, increased passenger discomfort and raise pollution levels, both exhaust and particulate.

The design of a 20 mph zone should ensure, as far as possible, that engineering measures take account of all road users, ensuring hazards are not created for vulnerable road users, particularly those people with a visual or mobility impairment.

Variable/Part Time Limits

Variable speed limits are those which lower the limit to 20 mph according to the time of day as specified in a speed limit order. The requirements for variable message signage are outlined in The Traffic Signs Regulations and General Directions 2016 (legislation.gov.uk).

Advisory 20 mph limits

SEDD Circular No. 6/2001 gave guidance on the situations in which it was appropriate to implement an advisory 20 mph maximum speed. Advisory maximum speeds were originally designed to be used in self-enclosed residential areas with little or no through traffic. Road authorities should be introducing mandatory limits or speed limit zones, as appropriate, in these areas rather than advisory ones.