A4/history
1923 Route
Originally, no roads in the City of London were classified. Consequently, the A4 started at the boundary between the Cities of London and Westminster where Fleet Street meets Chancery Lane. In 1927, the route was extended into the City along Cannon Street to end on the A3 at Monument Tube Station.
Between Hyde Park and Gunnersbury, the A4 ran along Kensington High Street, Hammersmith Road and Chiswick High Road up to the junction with Gunnersbury Avenue (then the A4000, now the A406. The original draft route ran along the historic Roman Road though Brentford and Hounslow, and along Bath Road. However, between the draft and final classifications, the A4 was chosen instead to run on the then under construction Great West Road, with the old road becoming part of the A315 and the A3006. Consequently the Historic Route Map on this page shows a gap in the A4 route over this length.
The A4's original western terminus in Bath was at the junction where Milsom Street (the A367) ended on George Street here. The current route of the A4 to the west of this point was the A431 to Lower Weston, the B4044 to Newton St Loe, and the A36 to Avonmouth.
Since this left a 20 mile gap between the end of the A4 and the Bristol Channel, the zone boundary had to be determined by other roads. This appears to be as follows :
- A367 from its endpoint to the A36
- A36 to the junction of Anchor Road and College Green in Bristol
- A4018 to Avonmouth (originally proposed to be the A36 in draft allocations before construction of the Portway started)
- A36 along Avonmouth Road and St Andrews Road to its terminus
Later Improvements
Twyford Bypass opened around 1927. In December 1929, the Colnbrook By-Pass was the subject of a number of road surfacing experiments, causing it to be known as the "Colnbrook Experimental Road".
The extension of the A4 to Avonmouth was designated in April 1935 as part of the widespread 1935 changes to road numbering.
Stage 1 of the Cromwell Road Extension from Chiswick Lane to the new roundabout at the Hammersmith Flyover junction (Great West Road) was opened in 1956 but it is unclear if the A4 was diverted over this section at that stage or later. Cedars Road and Ellesmere Road at the western end completed the bypass of Chiswick. Stage 2 included the Hammersmith Gyratory which opened on 13 July 1958 and the dual carriageway to Gliddon Road (which may have opened earlier). It is likely that the final section between Gliddon Road and North End Road opened in 1959 (to join the railway bridge section to Warwick Road which had opened in 1942) and the OS one inch map of March 1959 has this section fully shown as an A class road. The 1961 1:25000 map confirms that it as the A4.
Keynsham Bypass opened in 1966.
The Batheaston Bypass opened in July 1996.
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