A3 road

The A3 starts at King William Street at its junction with Gracechurch Street in the City of London, crosses 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 30 mph (48 km/h) to 40 mph (64 km/h). 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. The speed limit then increases to 50 mph (80 km/h) before going under the Coombe Flyover. The A3 then goes on a flyover by Shannon Corner in Raynes Park, before having junctions for New Malden, 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 reduces from 70 miles per hour (110 km/h) to 50 miles per hour (80 km/h), 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.[n 2]

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.

After passing Claygate, the motorway-standard section has junctions with the A244 between Esher and Oxshott, then the A245 between Cobham and Hersham.[n 3] The road's Wisley Interchange with the M25 enables a flyover still with a 70 mph (112 km/h) speed limit.[n 4] 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 50 mph (80 km/h) speed limit.[5] It returns to 70 mph (112 km/h) 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.

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[n 5]. 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[6] and Portsmouth Point.

Since the 2013 opening of the Hindhead Tunnel, the modern route (or, in the case of the southernmost section, its associated motorway section) is at least dual-carriageway, but at Liss is the sole at-grade roundabout. Widely considered the main traffic pinch-point and an accident hotspot (due to its unusual egg-shape and camber angle which can cause lorries at excess speed to tip over), there have been wide calls for its removal,[11] the projected increase in traffic with the completion of the tunnel supporting the proposal. In November 2010, the Highways Agency announced it would discuss three options for the roundabout's future, but in December it announced that no change would be commenced before 2015:[12][13]

• full-time signalling,
• removing the roundabout entirely (and thereby removing the A3/B3006 connection completely),
• keeping the existing system.

The slip road exiting the A3 leading to the Royal Surrey County Hospital and the Surrey Research Park regularly creates congestion on the main A3 during peak times, when the traffic queue reaches onto the main carriageway. In May 2011, it was announced that this is to be resolved with new improvements to the traffic system directly adjacent to the A3, with work funded jointly by the University of Surrey and Surrey County Council.[14]

Various schemes exist to manage urban traffic and economise land use, and include running park and ride services. The main such scheme along the route is in Guildford. In February 2015, the Mayor of London Boris Johnson announced plans to build over a short section at Tolworth, after visiting a similar site in Boston, Massachusetts; the Mayor said "rebuilding some of our complex and ageing road network underneath our city would not only provide additional capacity for traffic, but it would also unlock surface space and reduce the impact of noise and pollution." Similar plans have been proposed for other areas of London but proven cost-prohibitive.[15]

Cycle Superhighway 7 (CS7)
Queen Street towards Moorgate CS3 tow. Blackfriars CS3 tow. Tower of London Southwark Bridge/River Thames Southwark Cycleway 4 tow. Waterloo Cycleway 4 tow. London Bridge and Bermondsey A3 tow. London Bridge Tow. Elephant and Castle Cycleway 6 tow. Southwark Tow. Elephant and Castle ( ) A3/Ring Road tow. Elephant and Castle Ring Road tow. Vauxhall Kennington Road tow. Lambeth CS5 tow. Vauxhall A202 tow. Camberwell Oval A23 tow. Brixton Stockwell Clapham North ( Clapham High Street) Clapham Common station A3 tow. Wandsworth Clapham Common South Circular tow. Wandsworth South Circular tow. Streatham Hill Clapham South Balham Tooting Bec Tooting Broadway River Graveney Colliers Wood A24 tow. Mitcham and Sutton River Wandle Wandle Trail tow. Earlsfield Wandle Trail tow. Morden and Carshalton Merton High Street tow. South Wimbledon

In London, Cycle Superhighway 7 (CS7) runs either side of the A3 from Elephant and Castle to Clapham Common. The route is signposted and marked using painted blue cycle logos, carrying cyclists through Kennington, Stockwell, and Clapham. North from Elephant and Castle, CS7 runs along the A300/Southwark Bridge Road towards the City. South of Clapham Common, CS7 runs along the A24 to Colliers Wood, via Balham and Tooting.[18]

Between Wandsworth and Kingston Vale, a shared-use path runs alongside the A3 for cyclists and pedestrians. The path is segregated from other road traffic and links to cycle paths which run alongside the A308/Kingston Hill. This provides Norbiton with a traffic-free route to Wandsworth, which is also the terminus of Cycle Superhighway 8 (CS8 to Millbank).[19][20]

Shared-use paths and cycle lanes run alongside the A3 at points between the Greater London boundary and Portsmouth.

Between Thursley and Milford in Surrey, cycle crossings of the slip roads exist for cyclists travelling along the cycle lanes.

There is a cycle path between Liss and Petersfield which runs along the Portsmouth-bound (southbound) side of the A3. The route joins the A3 south of West Liss and leaves the dual-carriageway to the north of Petersfield (at Farnham Road). The route between Liss town centre and Farnham Road is part of National Cycle Route 22 (NCR 22).[21]

South of Petersfield, National Cycle Route 222 (NCR 222) follows the route of the A3 until the route reaches Waterlooville. The route passes through the Queen Elizabeth Country Park and passes along the eastern rim of Clanfield. The main cycle route between Petersfield and the Country Park follows NCR 22 through Buriton.[22]