A Turn Restriction is a restriction based upon a vehicle manoeuvre. The types of restriction include a prohibitive driving instruction, a mandatory driving instruction and implicit restrictions. Prohibited instructions are indicated by road signs within a red circle, and examples include No U-turns, No Right Turn and No Left Turn. These can include exceptions to the instruction and are typically elements like Except for Buses. Mandatory driving instructions are indicated by road signs within a blue circle or are painted on the roadway, and examples include Turn Right and Ahead Only. 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.
