|Length:||129.8 miles (208.9 km)|
|Meets:||M4, M5, M25, M49|
|Route outline (key)|
The A4 was the main road from the west of England to London before the coming of the M4. Its route from Avonmouth to London passes through the cities of Bristol and Bath, and the towns of Chippenham, Calne, Marlborough, Hungerford, Newbury, Reading, Maidenhead and Slough. It partly follows the route of the Great Western Main Line.
For more detail on the western end of the route, see A4/Avonmouth - Bath and A4/Bath - Chippenham. For more detail at the London end, see A4/Great West Road. Other sections are awaiting expansion as below.
A4 individual sections
- A4/Avonmouth - Bath
- A4/Bath - Chippenham
- A4/Chippenham - Marlborough (awaiting expansion)
- A4/Marlborough - Newbury (awaiting expansion)
- A4/Newbury - Reading (awaiting expansion)
- A4/Reading - Slough (awaiting expansion)
- A4/Slough - London (awaiting expansion)
- A4/Great West Road
Unlike fellow single digit Ax roads, the A4 has fewer changes. This is mostly due to the fact that the M4 follows closely to the route of the A4. Also of the other single digit Ax Roads, it is the only one to be extended since classification.
Notable locations and improvements
Hyde Park Corner
At Hyde Park Corner, the A4 takes the main line and it goes under it. This was built in the early sixies.
The Chiswick Roundabout is where the A4 become M4. It is also the meeting point of the North & South Circular roads.
The Maidenhead Bridge is the A4's crossing of the River Thames. It is in the town of the same name.
The Newbridge in Bath is one of the oldest bridges in Bath. It was opened in 1736.
|1959||Chiswick Flyover||Dual carriageway realignment and new junction.|