Work on Scotland’s largest civil engineering project started today as a specialist team launched a 750m length of the M74 over roads and rail tracks in Glasgow’s Southside.

More than 4,000 tonnes of steel are being inched painstakingly over the West Coast Mainline, edging towards their eventual destination on the other side of Eglinton Street.

Because of the sheer scale of the construction they are dealing with, engineers have opted to pull the westbound carriageway on to its concrete supports rather than lifting it with cranes. The 4,200 tonne, 135m preliminary structure – equivalent to the weight of 100 articulated lorries – will be edged from west to east at a rate of just 10m per hour, or less than nine inches per minute.

Work will be carried out in two-hour bursts in the dead of night, so as to avoid disruption to traffic and trains passing below, and it is due for completion in mid-February. Later sections will be added in the coming months, bringing the total length of the Port Eglinton viaduct, as it will be known, to more than 750m.

Until it meets its dock, however, the sheered off edge of the M74 will jut out awkwardly above the road and rail lines below, creating an eerie spectacle for passers by and drivers.

Floodlit against the night sky before work began around 1.30 this morning, the disconnected motorway made for an odd sight.

Even those onlookers who disagreed with the motorway project in principle agreed that they were impressed by the scale of the viaduct.

Ruth Elder, 39, from Govanhill, said she was concerned about extra traffic noise from the M74, and the fact she would have to walk through a lengthy underpass to get home every evening.

But despite her misgivings, she admitted she “liked the engineering”, and would be interested to see the finished motorway after its completion in 2011.

Dom Doyle, passing by as construction equipment was moved into place late last night, described the project as “amazing”.

“It looks impressive. I feel sorry for the people who stay here, but it’ll be good for travel,” said Mr Doyle, 42.

Taxi driver Robert Robertson, 55, said he hoped the new M74, in conjunction with improved bus and taxi lanes, would ease rush hours traffic congestion.

Authorities are confident the extension, which will close the gap between the M8 south of Kingston Bridge and the existing M74 at Fullarton Road, will be completed on time and on budget with a total cost of under £458 million.

Transport Minister Stewart Stevenson said work had been “moving on apace” since the first beams were lowered into place near the Kingston Bridge in July 2009.

“The M74 project is providing vital jobs and investment to the hard pressed construction industry,” he added. “Once complete, the M74 missing link will provide improved access to economic, employment and education opportunities for the people of Scotland.”

Project director David Welsh, overseeing work for the Interlink M74 joint venture, said the Port Eglinton viaduct represented “a major technical challenge” which required “innovative solutions” such as the pulley mechanism which will be used to drag the link into place over the coming weeks.

Councillor George Ryan, Glasgow City Council’s Executive Member for Business and the Economy, said the building work was a major jobs boost for the area, and the work would swell the city’s coffers once the motorway is completed.

The project is a partnership between the Transport Scotland, the principal funder, and Glasgow City, South Lanarkshire and Renfrewshire Councils.

The contractor is Interlink M74 JV, a joint venture comprising Balfour Beatty, Morgan Est, Morrison Construction and Sir Robert McAlpine.

There is a fixed construction cost of just under £445m, plus an allowance of £12m for possible treatment of old mine workings along the line of the route.

It is anticipated the motorway link will open in 2011.

TIMES FILE

• The new motorway section is one of Scotland’s biggest civil engineering projects.
• The launch section weighed 4,200 tonnes – the same as 100 articulated lorries.
• It is 147 yards (135metres) long, and will form part of a bridge totalling 820yds (750m), split into 12 spans on concrete supports.
• It is being pulled over the West Coast Mainline and Eglinton Road at a rate of about nine inches a minute.
• Work on the Eglinton Viaduct will be carried out in two-hour overnight bursts, and is due to be completed in 8-12 days.
• The £450m five-mile M74 extension is due to open in 2011.