Work began at long last today on the £47.9 million scheme to create the Bingley relief road - more than 30 years after it was first mooted.

The first diggers were fired up early this morning as construction workers began preparing the site of the five-kilometre-long stretch of dual carriageway from Crossflatts roundabout to Cottingley Bar.

Over the coming months the Aire Valley will become a hive of activity as hundreds of workers divert streams, level land and start on the 26 technically-challenging structures along the route including a multi-million pound viaduct at Cottingley.

Campaigners have welcomed the road saying it will bring an end to decades of traffic congestion which has blighted the town centre.

All the work, being carried out by Amec Capital Projects - due to finish in late 2003 - will be managed from a main site compound set up on the Castlefields Industrial Estate and drivers travelling through the town have been warned to prepare for delays while it is being carried out.

Contractors have moved in - confident that the huge civil engineering project costing £47.9 million will open on schedule in late 2003.

Over the next two years, 500 workers will lay 25,000 cubic metres of concrete, install 2,000 tonnes of structural steel work and finally cover it all with 40,000 tonnes of black top surfacing as a new road is constructed to end the nightmare bottleneck that is Bingley town centre.

The whole project is estimated to take a million hours of manpower from design to completion of the road which will bypass the town centre.

For Highways Agency project manager Peter Scally today marks the culmination of a long involvement with the scheme.

He said: "I am very pleased it has come to fruition because I was involved in 1975 and attended the public inquiry into the Aire Valley Trunk Road which ended in disorder and was abandoned.

"I travel to work by train and each day I see traffic snarled up in Bingley and it will be good to see the congestion which has blighted Bingley for such a long time removed."

Phil Girling, construction director for Amec, said using the design and construct programme would enable the new road to open by the end of 2003 as work would be carried on simultaneously at different sections on route.

He said: "We are confident it is a realistic programme and the Highways Agency is confident the costings presented to them are realistic or they would not have contracted it out to us.

"In terms of construction traffic, people will only notice a difference when we start moving into major spoil shifting and that will not be until next Easter. You won't see the black going down until the early part of 2003."

The first works will enable the contractors to start on 26 major structures on route. Streams will be diverted, land will be levelled and preparation work will start to build a bridge near Crossflatts station. Later this year workers will start to construct a multi-million pound viaduct over the River Aire at Cottingley which will be a major feature of the route.

Eric Pickering, site representative for agents Bapti, said: "One of the first areas we will tackle is to culvert a stream at Morton Beck and create a tunnel which will allow vehicles to run over the beck but all the work we are doing initially is enabling work along the route."

Mark Rand, president of Bingley Civic Trust, which has supported the relief road since the idea was first aired publicly, said he was delighted that the first sods were being lifted.

"It will enable the regeneration of the town and particularly the town centre where it's quite obvious that business is blighted by traffic. I look forward to the relief, quite literally, the new road will bring."

Pat Rand, chairman of the Better Bingley Campaign, established to fight for the road a decade ago, said it was wonderful to finally see the signs declaring work was starting.

Shipley Labour MP Chris Leslie, who pressed ministers to agree the scheme, said: "There will be disruption but in the long run it will prove worth it because people will realise it is better to have a bit of disruption for the sake of a better transport system in the long term."

A control centre for the work has been set up on the Castlefields estate.

Mr Girling said they would be trying to reuse most of the spoil generated at the point of excavation. Any remaining material would be deposited locally.

Protesters today condemned the start of work on the relief road, claiming it would increase traffic by more than 60 per cent.

Transport 2000, the national environmental transport pressure group, believes a package of sustainable transport measures with a park and ride scheme at the town station would better ease congestion.

Lynn Sloman, assistant director of the campaign, said it would increase peak hour car commuting into Bradford.

Bingley Environmental Transport Association yesterday held a protest march and picnic along the route of the road from Crossflatts to Bingley South Bog.

The group fears the road will damage the bog, a Site of Special Scientific Interest.