3. In this Schedule—
“linking carriageway” means the carriageway in the vicinity of junction 3A of the M42 northbound commencing where it diverges from the M40 northbound carriageway and ending where it merges with the M42 northbound carriageway;
“northbound slip road” means the road for entering the M40 northbound in the vicinity of junction 16 of that motorway, from the A3400, commencing at the zone sign and ending where it merges with the M40 northbound carriageway; and
“zone sign” means a sign authorised by the Secretary of State under section 64 of the Road Traffic Regulation Act 1984 for the purpose of indicating that vehicles are entering a specified road.