High Quality Content by WIKIPEDIA articles! The A3, known as the Portsmouth Road for much of its length, is a major road connecting London and Portsmouth passing close to Kingston upon Thames, Guildford, Haslemere and Petersfield. For much of its 67-mile (108 km) length, it is classified as a trunk road and therefore managed by the Highways Agency. Much of the road has been upgraded to a dual carriageway standard. Close to its southerly end traffic for Portsmouth is signed via the A3(M), A27 and M275. However the designation A3 is still used to identify the old road.