2,000 Tonne Rail Bridge Slide ensures M8 M73 M74 upgrade is on track

The Cabinet Secretary for Infrastructure, Investment and Cities, Keith Brown, visited the site to view construction progress ahead of the significant milestone in the major infrastructure project.

The new rail bridge, weighing in excess of 2,000 tonnes, slid into its final position next to the existing Cutty Sark rail bridge over the A8 at Bargeddie.

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

Mr Brown, said: “This impressive structure is the first to be completed as part of the Scottish Government’s £500m investment in Scotland’s Motorway network.

“The M8 is a main artery of the Scottish economy and the Scottish Government is committed to improving connectivity between our two biggest cities, cutting congestion, attracting inward investment and stimulating continued growth of our business communities. Now the bridge is in place, I look forward to seeing the new M8 take shape in the months ahead.”

Scottish Roads Partnership, the consortium responsible for designing, building, financing and operation the project, took possession of the rail line on 11 July and will return it to Network Rail on 26 July.

The bridge slide was the culmination of many months of meticulous preparation in consultation with Network Rail.

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 Savvedra, 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 which will carry the weight of the structure.”

A Self-Propelled Modular Transporter (SPMT) system was used 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 eight hours (tbc).

Now the bridge has been successfully installed, the construction team will use the remainder time to excavate the earth below it, creating the bridge opening for the new M8 motorway as well as lay the ballast, track and return the overhead lines to the new railway bridge allowing rail services to recommence on the 27^th July.

The M8 M73 M74 Motorway Improvements Project is upgrading the core of Scotland’s motorway network and will boost Scotland’s economy by improving connections between the commercial centres of Glasgow and Edinburgh and beyond.

The project marks a £500m investment in Scotland’s trunk road network and aims to tackle congestion problems on the A8/M8, M73, M74 and at key junctions including Raith (M74/A725) and Shawhead (A725/A8).

The benefits of the investment will improve journey times during peak periods, improve connectivity, journey time reliability and road safety across the Central Scotland motorway network. The project will also help promote sustainable economic growth by improving access to facilities and employment areas.