Elizabeth Stuart, Queen of Bohemia

A308(M)
A308(M) highlighted in blue
Route information
Maintained by National Highways
Length	0.6 mi (970 m)
Existed	1971–present
Major junctions
East end	M4 Junction 8/9
Major intersections	M4 motorway A404(M) motorway
West end	Maidenhead (Braywick)
Location
Country	United Kingdom
Primary destinations	Maidenhead, Windsor, Bracknell
Road network
Roads in the United Kingdom Motorways A and B road zones
← A194(M) → A329(M)

The A308(M) is a motorway in Berkshire, England. It is 0.6 miles (0.97 km) long. It forms part of the Maidenhead bypass and runs from the M4 at junction 8/9 to the A308 south of Maidenhead town centre. The A308(M) is generally considered to be Britain's second shortest motorway, after the A635(M) on the Mancunian Way.^[1]

In 1961^[2] the A4(M) was opened and ran from the existing junction 7, through a junction with the A308 and ending at a junction with the A4. In 1963, the Slough bypass was opened^[2] to junction 7 and the A4(M) was renumbered M4, junction 8 being with the A308 and junction 9 with the A4.

The proposed route of the M4 was then changed to go south of Reading, instead of north of it. When the M4 was extended in 1971,^[2] a new junction was provided to connect with what would become a spur. This new interchange was built too close to the original junction 8, so this had to be closed. A new junction (numbered 8/9 so as not to confuse motorists) was built. The original M4 north of this was renumbered as the A423(M) and in the 1990s this was again reclassified as the A404(M). A new spur, the A308(M), was built to maintain access to the A308 and connected with the A404(M) and the M4 at the same grade separated roundabout.

Note: motorway has no junction numbers

Information above gathered from Advanced Direction Signs April 2011

• List of motorways in the United Kingdom
• A404(M) motorway