The A41 is a trunk road between London and Birkenhead, England. Now in parts replaced by motorways, it passes through or near Watford, Kings Langley, Hemel Hempstead, Aylesbury, Bicester, Solihull, Birmingham, West Bromwich, Wolverhampton, Newport, Whitchurch, Chester and Ellesmere Port.
With the opening of the M40 extension in 1990 from junction 8, much of the route was downgraded. The sections between Bicester and the M42 near Solihull in the Midlands have been re-classified B4100, A4177 and A4141.
Route
London to Kings Langley
The route begins at Marble Arch from its junction on the A40 road in London with Portman Street/Gloucester Place (northbound) and Baker Street/Orchard Street (southbound). Named the Finchley Road, the A41 is dual-carriageway through Swiss Cottage and Hendon Way and intersects with the North Circular Road near Brent Cross shopping centre. The road passes through Hendon and after the junction with the A5150, (close to the Metropolitan Police's police college and the RAF Museum). The A41 overlaps the A1 at Five Ways Corner with the section known as Watford Way. It passes through Mill Hill, separating with the A1 at Apex Corner roundabout After crossing the M1, near Elstree, it links the M1 at Junction 4, and then meets the A5 at a roundabout (where the A5 becomes the A5183). The A41 continues alongside the M1 into Hertfordshire. This section is known as Elton Way, as far as the roundabout with the B462.
Running parallel to the M1, it intersects with junction 5 (Berrygrove Interchange). The road continues north, passing over the River Colne, to the east of Watford, crossing the A412 near Garston at "the Dome roundabout". After passing under the junction with the A405, the A41 turns towards the west. At a roundabout, with the A411 to Watford to the south, and the M25 spur straight ahead to join the M25 westbound at junction 19, the A41 continues north through Hunton Bridge crossing the River Gade and the Grand Union Canal to meet the M25 at junction 20. The old route through Kings Langley is now classified A4251. It used to follow the route of the Roman road, Akeman Street, between Berkhamsted and Bicester. The London to Aylesbury section was a similar route to the Sparrows Herne Turnpike Road.
Kings Langley to Tring
North of the M25, the road is a near motorway standard "A" road with all junctions grade-separated via underpasses or flyovers, but curves and gradients a little steeper. There are no hard shoulders but frequent lay-bys. It climbs through the Chiltern Hills then descends into the valley of the River Bulbourne crossing water meadows just outside Hemel Hempstead at Boxmoor. There are grade-separated junctions with the A414, A4251 (the earlier route of the A41) and A416. The route returns to open country north of here, passing west of Berkhamsted. It passes the National Film Archive. Before Tring, near Wigginton, it crosses the Icknield Way Path and Chiltern Way. An arched footbridge spans the road just near the summit before it passes just east of Tring (for the Ridgeway footpath) and descends the Chiltern scarp into the Vale of Aylesbury.
The Tring bypass was built in 1973 as the first section of the Watford-Aylesbury A41(M) motorway. On 6 July 1987, this section was downgraded to A41. The Tring bypass ends with the junction with the B4635, B4009 (the former route through Aston Clinton) and B488.
The A41 from junction 20 of the M25 to the Tring bypass was built in the early 1990s and opened in two sections: the £23.9m Berkhamsted bypass opened September 1993 and the £32.7m Kings Langley bypass opened August 1993.