From Roader's Digest: The SABRE Wiki
Route
For much of its length, this road is known as Watling Street, reflecting its historical roots as a Roman Road. Formerly known as the A5, the road was re-designated as A5183 because it is bypassed by the M1 Motorway.
Elstree - St. Albans
The A5183 begins at Elstree at a roundabout with the A41 Watford Bypass and the A5 Brockley Hill. It runs northwards through the village of Elstree, continuing through Radlett and Park Street to the Park Street roundabout where it intersects with the A414, the A405 and the former M10.
Peahen Crossroads, St Albans
The A5183 continues northwards into St Albans, to the Peahen junction where it 'cannons' with the A1081 (former A6). (A cannon occurs where two roads meet at a junction but do not cross each other.) It then bypasses Redbourn on its way to M1 junction 9 at Friars Wash where the A5 number resumes.
Trivia
The A5183 forms the boundary between the 4-zone and 5-zone for A road numbering. At the Peahen junction in St Albans it meets the A1081 which forms the boundary between the 5-zone and the 6-zone. The 5-zone is therefore split into two sections by this junction, and it is possible to use the diagonal crossings at the traffic signals to cross directly from the 4- to 6-zone
Original Author(s): M4 Simon
