The report will examine the environmental impact

Transport expert Professor Phil Goodwin will advise the government in the autumn on whether the �3bn proposed scheme would be cost effective.

Under the plans an extra lane would exist from junction 11 at Cannock, Staffs, to junction 19 at Knutsford.

The Group Against Motorway Expansion (GAME) has welcomed the inquiry.

It claims widening could have implications in terms of extra traffic, carbon emissions and local noise and air pollution.

Prof Goodwin's report will look at how widening would affect the amount of traffic and the impact on the local road network when cars come off the motorway.