From Roader's Digest: The SABRE Wiki
|North Orbital Road|
|From:||Hunton Bridge (TQ097996)|
|To:||Park Street (TL144050)|
|Length:||4.8 miles (7.7 km)|
|Meets:||A41, A412, M1, M25, A414, A5183|
|Old route now:||A412, M25, A414|
|Route outline (key)|
Hunton Bridge - Park Street
Starting at a roundabout GSJ on the A41 Watford bypass, the A405 heads east then north to bypass Abbots Langley. Although the road is D2 the speed limit is 40mph owing to the large number of side roads and occasional roundabout.
The limit increases to 50 before the A405 reaches the M1 at the parclo J6. Now carrying traffic between central London via the M1 and the M25, the road then passes to the west of Bricket Wood and soon reaches a roundabout at M25 J21A.
On the far side of the motorway - and still D2 - the road bears right at the next roundabout to bypass Chiswell Green and presently reaches the Park Street Roundabout to the south of St Albans where it meets the former A5 (now A5183) and former M10 (now A414). The road ends here.
The A405 was originally planned as part of a London orbital.
When originally built in the 1930s the road ran from the A41 in Watford to the A555 (now A1) Barnet bypass, passing to the south of St Albans. By the 1970s the road had been extended west to bypass Rickmansworth and meet the A412 at Maple Cross.
The Rickmansworth bypass was later upgraded and incorporated into the M25 as the section between J17 and the spur at J19 (although the spur at J17 is now the A412). Later still the St Albans bypass was incorporated into a rerouted A414, giving the road its current length.