Question to the Department for Transport:

To ask the Secretary of State for Transport, what process National Highways uses to determine variable speed limits on smart motorways.

Smart motorways have variable mandatory speed limits to smooth traffic flow and reduce congestion and have electronic signs to warn drivers of incidents ahead.

Variable speed limits will often be triggered automatically when congestion is starting to build up ahead, or when the volume of traffic has reached a point where this is about to happen. Operators in National Highways’ regional control rooms are in overall control of this system and take a strategic regional view of the network. They can override speed limits or set them manually where needed; for example, to deal with a complex incident, help a vehicle leave an emergency area and re-join the carriageway, or provide a safe space to work for road workers as they set out or remove cones and temporary signing.