We publish guidance for highway authorities on the design of traffic calming measures, including road humps, in Local Transport Note (LTN) 01/07 ‘Traffic Calming’. This can be viewed via the following link:
In terms of the use of traffic calming measures including road humps, DfT circular 01/2013 ‘Setting local speed limits’ states that whilst the vast majority of traffic calming measures in use are speed humps, tables, cushions or rumble devices, traffic authorities will want to consider the full set of available measures.
It should also be noted that the revised Traffic Signs Regulations and General Directions 2016 add upright speed limit repeaters and road markings to the prescribed list of traffic calming features. These may now be used in addition to the self-enforcing features within signed 20 mph zones, and will enable local authorities to reduce the number of physical traffic calming features where vehicle speed is already around 20 mph due to the nature of the road.
The requirement is now for at least one physical traffic calming feature within a 20 mph zone. Beyond that traffic authorities may, at their discretion, place any combination upright signs, speed limit road markings or additional physical traffic calming features at 100 metre (maximum) intervals. In doing so they will need to carefully consider the implications for the self-enforcing nature of a 20 mph zone.
It is however ultimately for local authorities to decide whether they wish to install or remove road humps.