First bridge completed at £500m M8 M73 M74 improvements project

Video footage showing the construction of the first major structure as part of the £500 million M8 M73 M74 Motorway Improvements Project has been released by Transport Scotland.

The time lapse footage reveals the new rail bridge, weighing in excess of 2,000 tonnes, sliding into its final position over what will become the new M8 motorway, to join the existing Cutty Sark rail bridge at Bargeddie, Glasgow.

The completion of the bridge slide marks a significant milestone in the progress of the project and has been the culmination of months of meticulous planning and preparation between Scottish Roads Partnership (SRP), the contractor responsible for delivering the project, and its construction joint venture, Ferrovial Lagan.

The three minute video footage shows the complex engineering challenge beginning with the onsite construction of the bridge, the possession of the railway line and the bridge slide, and concludes with footage of the first passenger train successfully crossing the new bridge as scheduled.

M8 scheme map
Map of the project

SRP, the consortium responsible for designing, building, financing and operation the project, took possession of the rail line on 11 July, and returned it to Network Rail on 26 July as programmed, with rail services resuming the following day.

The new bridge will carry the Rutherglen and Whifflet rail line over the new M8, which is currently being constructed to the south of the existing A8.

Graeme Reid, project sponsor for Transport Scotland, said: “The success of the bridge slide marks a significant milestone as part of the M8 M73 M74 Motorway Improvements Project and is the first tangible improvement to the transport infrastructure.

“The time lapse gives a real sense of the challenges involved in delivering a project of this scale and encourages a greater understanding of civil engineering schemes and the benefits they can bring.”

The first phase of works involved the closure of the railway line over four weekends in April 2015, allowing the construction team to lay the foundations by installing eight piles (each two metres in diameter) and reinforce the ground on either side of the bridge. The three-span steel bridge was then built adjacent to the existing railway prior to the slide.

Dario Saavedra, construction manager for Ferrovial Lagan Joint Venture, said: “The installation was complex due the strict limit on time as a result of the railway closure.

“The operation included the removal of the existing railway infrastructure including overhead lines, rail tracks and the embankment, before the steel and concrete bridge could be pushed into its final position over the pre-cast piers to carry the weight of the structure.”

The construction team used a Self-Propelled Modular Transporter (SPMT) system to slide the 2,000 tonne structure into place. Six SPMT platform vehicles, fitted with row upon row of rubber wheels were moved into position under the structure to carry the weight of the bridge to the ground.

A computer controller was used to simultaneously drive the six SPMT platforms carrying the bridge structure 50 metres north, in an operation that lasted approximately four hours.

Ewan Angus, major projects director at Amey added: “The project to complete the Central Scotland motorway network is an enormous civil engineering challenge with many different technical complexities, not least this bridge design. With more than 170 Amey designers and engineers developing almost 500 design packages, the project is providing invaluable opportunities for graduates and apprentices, creating Scotland’s engineers of the future.”

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