Transport Scotland has outlined its plans to progress major infrastructure projects by 2011, amid calls by a coalition of environmental groups to deliver ‘healthy, low carbon transport’.

The three-year corporate plan due to run from 2008-11 sets out the role the agency will play in delivering the Scottish Government’s strategic priorities – wealthier and fairer; smarter; healthier; safer and stronger; and greener.

By the end of 2011 Transport Scotland pledges to have started projects, including the M74 extension and other major road upgrades in the Glasgow area, to be completed for the Commonwealth Games in 2014, as well as the Aberdeen western peripheral route.

The Forth replacement crossing will be ready for construction, and construction of the new rail link to the borders will have started, the agency said.

Chief executive Dr Malcolm Reed said: ‘We have significant challenges ahead, not least in recognising and adapting to the changing climate, which includes, where appropriate, promoting more sustainable means of transport and public transport alternatives.’

But a coalition of six environmental and transport groups have written to transport minister, Stewart Stevenson, challenging the Scottish Government to deliver action on sustainable transport.

It is calling for a national programme of investment in walking and cycling; priority for buses and multi-occupancy vehicles on main roads; an inter-city rail network to match the best in Europe; and a strong focus on smarter-choice measures aimed at tackling peak-hour congestion.

The six groups are Friends of the Earth Scotland, Scottish Association for Public Transport, Spokes, Sustrans Scotland, Transform Scotland and WWF Scotland Colin Howden, director of Transform Scotland, said: ‘Unless action is taken, rising traffic levels will rule out the prospects of the Government's climate change targets being met.’ Up to 2011, the Scottish Government has allocated £6.5bn to Transport Scotland for investment in transport infrastructure.