M3 motorway

The M3 is a major motorway running 95 kilometres from Sunbury-on-Thames in Surrey to Eastleigh in Hampshire. It passes through towns such as Aldershot, Basingstoke, Winchester and Southampton. The road was built in stages between 1971 and 1995, with the final section through Twyford Down meeting strong opposition from environmental campaigners. A two-lane stretch remains between junctions 8 and 9, while the rest is mostly dual three-lane carriageways. Smart motorway upgrades have added permanent running lanes in places, turning former hard shoulders into traffic lanes. The motorway was planned to relieve congestion on two older trunk roads that could no longer cope with rising traffic. The first section opened in 1971 at a cost of £46 million, extending the A316 Country Way from London. Later phases faced public inquiries and legal challenges, especially around Winchester where the route cut through water meadows near St Catherine’s Hill. The busiest section, near Chandler’s Ford, now carries about 130,000 vehicles daily. A notable feature is the Spitfire Bridge over the M3, named after a wartime aircraft mistakenly thought to have flown beneath it. The road crosses the River Thames at Chertsey and runs through heathland near Bagshot. It passes close to Basingstoke and skirts the northern edge of Winchester, where it cuts deeply through Twyford Down. Near Winchester the M3 meets the A303 towards Exeter and the South West. The motorway ends at Chilworth Roundabout on the edge of Southampton, where the M27 provides alternative routes to the city centre and waterfront. A private exit serves the site of the former Sun Microsystems headquarters, now a housing estate called Helios Park.