By Ben Jeffrey BBC News Online in Birmingham

A road to relieve congestion around the M6 was first suggested in 1980

The need to relieve traffic congestion around the M6 in the UK's industrial heartland was first identified by the Conservatives as far back as 1980.

But it was 1990 before the government invited private firms to bid for the contract to build the route, the year it was confirmed the development would be a private toll road.

Two public inquiries and a series of protests against the proposed route helped to push back the start of building work until 2001, 10 years after Midland Expressway Ltd (MEL) was appointed to run the project.

Campaigners have raised financial, environmental and practical objections to the route, which was known as the Birmingham Northern Relief Road (BNNR) until it was renamed as the M6 Toll in 2001.

A timeline of the M6 Toll 1980 - Government proposes a new Midlands motorway 1986 - Preferred route announced 1988 - First public inquiry 1991 - MEL announced as the bid winner to build the road 1994-5 - Second public inquiry 1999 - Alliance Against the BNNR's challenge defeated 2001 - Main construction work begins 2003 - M6 Toll opens

The first public inquiry into the scheme was held in 1988 and was followed by another which lasted more than a year, from June 1994 to October 1995.

An informal coalition opposing the project, initially set up by West Midlands Friends of the Earth, evolved into the Alliance Against the BNRR.

It brought together more than 30 organisations, including environmental groups, and residents who lived in villages and communities along the length of the route.

Groups opposed to the BNRR had hoped Labour's defeat of the Conservatives in 1997 would signal the end of the controversial project.

But the courts upheld the new government's decision to build the road, in what protestors claimed was a revision of its position before the election.

A number of protest camps were set up along the route between November 1997 and January 1999, when the last one was cleared.

Many of the objections to the project were on environmental grounds.

The road is the UK's only toll motorway

The road runs through four Sites of Special Scientific Interest (SSSI) and protestors say the work to build it has severely damaged one of them, Chasewater Heath.

MEL said it spent several months examining the impact of the project on all kinds of wildlife.

The firm had to apply for compulsory purchase orders for properties along some of the route, although it said only 40 buildings needed to be demolished and about six businesses closed during the road's construction.

The company also brought in specialists to carry out archaeological digs at several points along the 27-mile route between 2000 and spring 2001, when construction work was finally able to begin.