A3
Route information
Length	72 mi (116 km)
Major junctions
North-east end	City of London 51°30′39″N 0°05′12″W / 51.5108°N 0.0866°W / 51.5108; -0.0866 (A3 road (northern end))
Major intersections	A2 A23 A24 A205 M25 A31 A3(M) A27 M27 M275
South-west end	Portsmouth Harbour 50°47′30″N 1°06′31″W / 50.7918°N 1.1086°W / 50.7918; -1.1086 (A3 road (southern end))
Location
Country	United Kingdom
Primary destinations	Kingston upon Thames Guildford Petersfield
Road network
Roads in the United Kingdom Motorways A and B road zones
← A2 A4 →

The A3, also called the Portsmouth Road or London Road in some parts, is a major road that connects the City of London to Portsmouth. It passes near places like Kingston upon Thames, Guildford, Haslemere, and Petersfield. The road is 67 miles (108 km) long and is mostly a trunk road, which means it is managed by National Highways. Almost the entire road is a dual carriageway or wider. Except for some bypasses in London, the road generally heads southwest, and after Liss, it goes south-southwest.

The A3 road runs roughly parallel to the Portsmouth Direct Line railway. However, the railway goes directly through all the towns that the road passes by. The towns of Havant and Woking are located 2 miles (3.2 km) and 3 miles (4.8 km) away from the road, respectively.

The A3 begins at King William Street, where it meets Gracechurch Street in the City of London. It crosses the River Thames at London Bridge and enters the London Borough of Southwark, continuing southwest along Borough High Street and Newington Causeway to the Elephant and Castle roundabout. From there, it follows Newington Butts and enters the London Borough of Lambeth on Kennington Park Road, which turns into Clapham Road and Clapham High Street.

The A3 then turns west onto Clapham Common North Side, with the A24 continuing straight ahead. It enters the London Borough of Wandsworth and runs alongside the A205 'South Circular' along Battersea Rise, Wandsworth Common North Side, and East Hill, passing through Wandsworth. The A205 continues west toward Richmond.

On West Hill, just east of the Tibbets Corner junction with the A219 near Putney Heath, the road widens from one lane each way to a three-lane dual carriageway, and the speed limit increases from 30 to 40 mph (48 to 64 km/h). The A3 then continues southwest between Richmond Park and Wimbledon Common as Kingston Road, eventually bypassing Kingston upon Thames and passing through Roehampton Vale. It enters the Royal Borough of Kingston Upon Thames just before Kingston Vale, where there is a junction with the A308 for Kingston upon Thames and Richmond Park.

The A3's Kingston Bypass now ends earlier, leaving a spur junction with the A309 that leads to the Scilly Isles junction near Sandown Park in Esher. From there, the road becomes the Esher Bypass, on the border of Hook in London and Long Ditton in Surrey. At this point, the speed limit increases to 70 mph, with three lanes and a motorway-grade hard shoulder.

After passing Claygate, the motorway-standard section has junctions with the A244 between Esher and Oxshott, and the A245 between Cobham and Hersham. The road then reaches the Wisley Interchange with the M25, where a flyover maintains the 70 mph (110 km/h) speed limit. The A3 bypasses Wisley, Ockham, Ripley, and Burpham (a suburb of Guildford) before cutting through Guildford itself as a dual carriageway, where the speed limit drops to 50 mph (80 km/h).

The road returns to a 70 mph (110 km/h) speed limit at the junction with the A31 and A246 before bypassing Godalming and Milford. It continues through a tunnel at Hindhead, built in 2011 to increase capacity and bypass the Devil's Punch Bowl, before leaving Surrey.

A3(M)
The junction between the A3(M) and the A27
Route information
Maintained by National Highways
Length	5 mi (8.0 km)
Existed	1979–present
Major junctions
Northeast end	Horndean
Southwest end	Bedhampton
Location
Country	United Kingdom
Primary destinations	(London), (Portsmouth), (Chichester), (Petersfield), Waterlooville
Road network
Roads in the United Kingdom Motorways A and B road zones

This section of the road opened in 1979 and serves as an alternative route to the A3 in this part of Hampshire.