The M3 is the road south-west from London, serving the densely populated towns in the west of Surrey, the north of Hampshire and the south of Berkshire. It also carries traffic heading for the busy destinations of Southampton, Bournemouth and Poole via the A31, and the south west via the A303. All of these places have considerable demand for travel to and from London. As a result, the M3 is not especially long as major inter-urban motorways go, but it certainly isn't quiet.

For much of its existence, the M3 ran from the outer edges of London to Popham, west of Basingstoke, where it split to feed traffic into the A30 and A33. In the mid-1980s work started to extend it south, along the line of the A33, to reach Southampton, with the work progressing in sections until it ran both north and south of Winchester. The A33 Winchester Bypass had been built in the 1920s, making it one of the oldest sections of dual carriageway in the UK, and had intermediate junctions controlled by traffic lights. It was left to deal with all the M3's through traffic.

In the way of the M3's completion was St Catherine's Hill - a very ancient and very important hill fort, which the Winchester Bypass avoided by squeezing between the hillside and the river on a twisting path that was unsuitable for a motorway. There was no easy way around the obstacle.

The final section of the M3, which eventually opened in 1995, was built by carving an exceptionally deep cutting through high ground to the south east of St Catherine's Hill, leaving the ancient monument intact but destroying a picturesque and scientifically interesting bit of countryside. Its name stays in the popular conscience even today, such were the monumental protests that the construction of the road caused. Twyford Down is sometimes regarded as the beginning of the backlash against road building that saw construction of new roads in the UK fall out of favour with politicians of all colours for many years, and to this day the word 'motorway' tends to be avoided on new road schemes.

At its southern end, the M3 is fortunate enough to have its traffic effectively distributed by the M27, which kindly prevents all six lanes from piling into the northern suburbs of Southampton and is the sort of effective terminus that many other motorways probably ought to have.

Start
London
End
Southampton
Passes
Staines, Bracknell, Basingstoke, Winchester
Connects to
Length
61 miles
Open Junctions Section
Jun 1971 J3-8 Lightwater → Popham
Jul 1974 J1-3 Sunbury → Lightwater
Aug 1985 J8-10 Popham → Bar End
Dec 1991 J12-14 Pitmore → Chilworth
Jun 1995 J10-12 Bar End → Pitmore

Exit list

Junction   Northbound               Southbound  
1
24.8 km
Sunbury
Kingston
A308
Central London
A316




A308
NORTH
A316




A308
N/A
LanesLanesLanesLanesLanes SignsSigns LanesLanesLanesLanesLanes SignsSigns
6 miles, 3 lanes 6 miles, 3 lanes
2
34 km
Gatwick Airport (M23 Link)
Heathrow Airport (M4 Link)
The NORTH (M1 Link)
Dartford & (M20 Link)
Chertsey (A320)
Staines (A30)
M25 Link
M25
(M1)
(M4)
(A30)
M25
(M20)
(M23)
(A320)
Gatwick Airport (M23 Link)
Heathrow Airport (M4 Link)
Chertsey (A320)
Staines (A30)
M25 Link
LanesLanesLanesLanesLanesLanes Signs LanesLanesLanesLanesLanesLanesLanes Signs
7 miles, 3 lanes + HSR 7 miles, 3 lanes + HSR
3
45.5 km
Woking
Bracknell
Lightwater
A322
A322 A322 Woking
Bracknell
Lightwater
A322
LanesLanesLanesLanesLanesLanes Signs LanesLanesLanesLanesLanesLanes Signs
5 miles, 3 lanes + HSR 5 miles, 3 lanes + HSR
4
52.5 km
Guildford
Farnham
Camberley
Farnborough
Aldershot
A331
A331 A331
(A325)
Guildford
Farnham
Camberley
Farnborough
Aldershot
A331
LanesLanesLanesLanesLanesLanes Signs LanesLanesLanesLanesLanesLanes Signs
2 miles, 3 lanes + HSR 2 miles, 3 lanes + HSR
4A
55.5 km
Farnborough (W)
A327
Fleet
(A3013)
A327 A327
(A3013)
Farnborough (W)
A327
Fleet
(A3013)
LanesLanesLanesLanesLanesLanes Signs LanesLanesLanesLanesLanesLanes Signs
3 miles, 3 lanes 3 miles, 3 lanes
59.5 km Services Fleet Services Fleet
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
4 miles, 3 lanes 4 miles, 3 lanes
5
68 km
Hook
B3349
A287
B3349

A287
A287 Hook
B3349
A287
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
5 miles, 3 lanes 5 miles, 3 lanes
6
75 km
Basingstoke
Newbury
Alton
A339
Reading (A33)
(A33)
(A339)
Basingstoke
Newbury
Alton
A339
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
5 miles, 3 lanes 5 miles, 3 lanes
7
83 km
Basingstoke
A30
(A30) Basingstoke
A30
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
2 miles, 3 lanes 2 miles, 3 lanes
8
85 km
(A303) The SOUTH WEST
Andover
Salisbury
A303 Link
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
6 miles, 2 lanes 6 miles, 2 lanes
96.5 km Services Winchester Services Winchester
LanesLanesLanesLanes LanesLanesLanesLanes
4 miles, 2 lanes 4 miles, 2 lanes
9
102 km
The MIDLANDS
Newbury
A34
A34 A272 Winchester
A272
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
2 miles, 3 lanes  
10
105.5 km
Winchester (City)
B3330
Alton
A31
B3330 A31
LanesLanesLanesLanesLanes
2 miles, 3 lanes 4 miles, 3 lanes
11
107 km
Winchester (S & W)
A3090
A3090


(A3090)

B3335




Winchester
A3090
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
4 miles, 3 lanes 4 miles, 3 lanes
12
112.5 km
Eastleigh (N)
A335
A335 Eastleigh (N)
Chandler'
s Ford
A335
LanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
2 miles, 3 lanes 2 miles, 3 lanes
13
115.6 km
Eastleigh
Chandler'
s Ford
A335





A335





A335
Eastleigh
A335
Southampton Vehicle Ferry
Bournemouth
M27 (W) Link
LanesLanesLanesLanesLanesLanes LanesLanesLanesLanesLanes
LanesLanesLanesLanesLanesLanesLanesLanes
1 mile, 4 lanes 1 mile, 2+2 lanes
14
117 km
N/A A27

M27






A33
SOUTH
M27



Southampton Airport
Fareham
Portsmouth
M27 (E) Link
Southampton
A33
LanesLanesLanesLanesLanesLanes LanesLanesLanesLanesLanesLanesLanesLanes
Routes

Picture credits

  • Photograph of the cutting at Twyford Down by Jim Champion.

With thanks to Ritchie Swann, Sam Borro, Ross Henderson, Johnny and James Denson for information on this page.