|Portsmouth (Broad Street) (SZ629996)
|78 miles (125.5 km)
| A10, A2, A23, A24, A205, M25, A31, A272,
A3(M), A27, M27,M275
|Route outline (key)
At the time of classification, no roads in the City of London itself were classified, and so the A3 started at the southern end of London Bridge. However, by 1927, it had been extended northwards along King William Street to start at Bank.
Construction of the Kingston Bypass started in 1923 and opened to traffic on 28th October, 1927 as a joint project with the A298 Merton Spur. The original road became an extension of the A308 into Kingston itself, and then an extension of the A307 to the bypass' original ending point at Littleworth Common.
The Esher Bypass joined onto the southern end of the Kingston Bypass, and opened to traffic on 15th December 1976. This left a short stub of Kingston Bypass west of Hook, which was renumbered as an extension of the A309.
The Ripley bypass opened in February 1976. The original A3 was downgraded to the B2215.
Construction of the original Guildford and Godalming Bypass started in 1929 and opened to traffic in June 1934. The bypass left the original A3 alignment at Stoke Park, and ran west along Woodbridge Road and Midleton Road, to rejoin the old road at Milford. The pre-bypass route was renumbered as the A3100. In August 1981, a second bypass opened, diverting the A3 away from the eastern section of the original bypass beyond the A322, which had numerous at-grade junctions and urban development. This old section of bypass became a western extension of the A25.The Godalming bypass was upgraded to full grade separated dual carriageway between the Hogs Back and Milford by the Compton to Shackleford Improvement Scheme, opening in 1989-90.
In December 1984 the A3 was dualled between Witley junction and Rodborough Hill. Following public consultation in 1985 and a preferred route announcement in 1986, the orders for the Milford Bypass were published in 1990 and the road opened in 1993. This created a continuous dual carriageway between Robin Hood Gate and Gibbet Hill.
A bypass for Liphook and Petersfield had been proposed since the early 1960s, but only opened to traffic in 1992 - the old road being downgraded to the B2070. In the intervening years between proposal and construction, several portions of the old A3 had been dualled online - most of these have now had one lane hatched out.
Between Petersfield and Horndean the road used to climb to the top of Butser Hill (not quite to the summit), and then snake down in a section known locally as 'Cannonball Corner'. At the bottom it would then climb Gravel Hill. Canonball Corner was replaced by a flat dual carriageway in the 1960s. Some of the old road is still visible by Queen Elizabeth Country Park, while most of it was demolished when the cutting was built.
In the 1960s a new southbound carriageway was provided on a much smoother alignment between Gravel Hill and Clanfield. Space was provided for both carriageways, but it was another 30 years before a new northbound carriageway joined it, making it look like any other dual carriageway. The old road became today's London Road, and a flyover replaced the crossroads.
South of here, a new southbound carriageway had been built between Clanfield and Horndean in the 1950s, ending at what's now the start of the A3(M). Again space was left for a wider road to be built. When the A3(M) opened in 1979, this section gained another new southbound carriageway, with the old southbound becoming the new northbound and the old northbound becoming a local access road.
The start of the A3(M) represents the point from which it would have been too difficult to widen the road online.
Through Cosham, the A3 originally ran through along the High Street and across the level crossing, before being by-passed by Northern Road by 1930. Northern Road was renumbered as the A397 when the M27 and M275 opened in the area in 1976.
After the opening of the Liphook and Petersfield Bypass, the A3 was a completely dual carriageway route from the M25 to the A27, except for the single carriageway route through Hindhead. After decades of negotiation and planning, the Hindhead Tunnel finally opened to traffic on 29 July 2011.