Restriction includes turn restrictions, restriction for vehicles, and access restrictions.
Turn restrictions are a restriction based upon a vehicle manoeuvre. This type of restriction includes prohibitive driving instructions, mandatory driving instruction and implicit restrictions. Prohibited instructions are indicated by road signs within a red circle, examples include No U Turn, No Right Turn or No Left Turn. These can include exceptions to the instruction and are typically elements like Except for Buses. Mandatory driving instructions indicated by road signs within a blue circle or painted on the roadway such as Turn Right, Ahead Only and Left Turn. Implicit restrictions occur where a turn is not signed as prohibited but would not be a normal manoeuvre. For example, where a road splits around a traffic island or at complex junctions where additional geometry has been captured to reflect the traffic flow. These are not differentiated from actual signed restrictions.
Restriction for vehicles are constraints that apply to the vehicles based on their physical characteristics: height, weight, width and length. These are required to protect structures such as bridges and tunnels from damage, or to restrict/prohibit use by vehicle that exceed specific dimensions, usually for environmental reasons.
Restriction for vehicles has been extended to support the full definition of height, weight, width and length restrictions as defined in the UK to ensure that they can:
Apply to specific vehicle types only
Relate to a structure for which the restriction is designed to protect (for example, a Bridge)