The M3 motorway is one of the UK's motorways linking West London (junction 1 at Sunbury) to Southampton and the M27 (junction 14). It crosses the M25 at junction 2. There are 3 lanes in each direction for the majority of the length of the motorway.
The motorway was built to relieve traffic from the old A30 and A33, the congested single carriageway trunk roads that traffic between the cities previously used. The Motorway was originally only built between London and Winchester, a few miles north of Southampton, because the Ministry of Transport (MoT) had trouble purchasing the land required to bypass Winchester. The land they wanted, on Twyford Down, east of the city, was owned by Winchester College, who refused to sell the land to the government because it was an important chalk grassland habitat. The government did not wish to issue compulsary purchase because they were on good terms with the college and did not want to sever ties. Proposals were made for a tunnel through Twyford Down, but because the estimated cost for this was £75 million more than the estimated cost for a cutting the government dismissed the plans. In 1990 a link between Southampton and the southern end of Twyford Down was completed and soon after work began on clearing the route across the down. Environmentalists, including the Dongas, gathered on the down making a camp to hinder work. A coalition of locals, and envrionmental organisations including Greenpeace and Friends of the Earth took the MoT to the high court stating that the road was against the government's own environmental protection laws. The case failed, but European Union minister for the Environment, Carlo Ripa de Meana looked into the case and ordered the project to stop because it violated British and EU laws. The MoT ignored this order, and when it took over the EU chairmanship later that year Carlo Ripa de Meana lost his job. The project was held up further as scientists and archaeologists worked hard to minimise the destruction caused by the project. In 1994 the link was completed, cutting an average of 5 minutes off the London to Southampton journey time.