Once south-west of the Elephant and Castle in Southwark, the road follows a route roughly parallel to the
Portsmouth Direct line railway which goes through, rather than past, all of the towns which the road serves, with
Havant and
Woking and , respectively, off the road.
Greater London The A3 starts at
King William Street at its junction with
Gracechurch Street in the
City of London, crosses the
River Thames at
London Bridge while entering the
London Borough of Southwark, and goes south-west along
Borough High Street and
Newington Causeway to the
Elephant and Castle roundabout. It continues along
Newington Butts, and bounds then enters the
London Borough of Lambeth on
Kennington Park Road which becomes
Clapham Road and
Clapham High Street. The A3 then turns west (leaving as its straight continuation the
A24) as
Clapham Common North Side. Along this road, it enters the
London Borough of Wandsworth, after which it runs
concurrently with the A205 'South Circular' along
Battersea Rise,
Wandsworth Common North Side and
East Hill, and goes through
Wandsworth, and then the A205 carries on west towards Richmond. On
West Hill, just east of the Tibbets Corner junction with the
A219 near
Putney Heath, the road increases from one lane each way to a three-lanes-each-way
dual-carriageway and the speed limit increases from . The A3 then continues south-west between
Richmond Park and
Wimbledon Common, as
Kingston Road before beginning to bypass
Kingston upon Thames while going through
Roehampton Vale. The A3 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. For the first south of Richmond Park, the A3 runs within of the
Beverley Brook, crossing it three times. Although there is no point where the stream itself can be seen when driving along the road, the bridge
parapets are visible and, for , where the road runs along the edge of
Wimbledon Common, the trees flanking the stream can be glimpsed across playing fields, with the lightly managed "natural" woodland of the common rising beyond. Except for the playing fields, the whole of the common, including Beverley Brook, is both a
Site of Special Scientific Interest (SSSI) and a
Special Area of Conservation (SAC). The speed limit then increases to before going under the Coombe Flyover. The A3 then goes on a flyover at Shannon Corner located on the edges of
Motspur Park,
Raynes Park and
New Malden, before having an additional junction for
New Malden, then
Tolworth and
Hook along the
Kingston By-pass. Brief features of a section of road contribute to a traffic pinch-point during
peak hours around the Hook underpass. The road reduces from three lanes to two in the underpass. The speed limit at this point in the London-bound direction reduces from , with the first of a handful of
Gatso speed enforcement cameras. If returning to London, traffic from the A309 also joins just before the underpass.
Surrey The A3's Kingston By-pass now ends sooner leaving a spur junction the A309 to the Scilly Isles junction near
Sandown Park,
Esher, its route instead becoming the
Esher By-pass on the border of
Hook, London and
Long Ditton,
Surrey. Here the speed limit rises to 70 mph, with 3 lanes and a motorway-grade hard shoulder. After passing
Claygate, the motorway-standard section has junctions with the A244 between
Esher and
Oxshott, then the A245 between
Cobham and
Hersham. The road's
Wisley Interchange with the
M25 enables a flyover still with a speed limit. It bypasses
Wisley,
Ockham,
Ripley (and
Burpham which is a suburb of
Guildford) before cutting through the major town itself as a dual carriageway and changing to a speed limit. It returns to at the A31 and A246 junction before bypassing
Godalming and
Milford. It continues through a tunnel at
Hindhead (constructed in 2011 to improve capacity and bypass the
Devil's Punch Bowl) before leaving Surrey.
Hampshire The A3 enters Hampshire just after exiting the Hindhead Tunnel, passes
Liphook and
Bramshott, turns
SSW past
Liss, then passes
Petersfield. The A3's original route between Hindhead and Petersfield, passing through several villages, became the B2070. At Liss, there remains an
at-grade roundabout, the only such junction on the route. Over the
South Downs, it passes Clanfield and
Horndean. From just north of Horndean, (still heading towards Portsmouth) the A3 separates from the
A3(M) (below) and continues as
London Road as far as Hilsea, south of which it is Northern Parade. It runs along the west side of
Portsea Island which forms Portsmouth proper, roughly parallel with the
M275, into the nearly waterfront centre of the city where, after passing the
Catholic cathedral, it meets with the
A2030. Here, it reaches
Old Portsmouth, passing the
Anglican cathedral and the 15th century harbour where it comes to an end at
Broad Street and
Portsmouth Point. ==Hindhead tunnel==