Another DJV-designed HS2 viaduct successfully slides into place

The 320-metre-long east deck was moved into position over the M6 near Birmingham Airport at the end of September, with both carriageways re-opened to traffic ahead of schedule.

It was the second phase of a multi-phase operation that will see two parallel viaducts installed, and for the first time on this project in the West Midlands the team used a ‘fully restrained’ sliding technique.

This meant the viaduct could be launched over the M6 Junction 4 slip road on the Friday before the weekend closure, maintaining traffic on the carriageway below. This new approach was introduced in collaboration with National Highways, to reduce the time of the operation and further minimise the impact on road users.

The team moved the viaduct using a series of winches, known as strand jacks, at an average speed of 10 metres per hour. To reduce friction, the structure was slid across non-stick pads, using a material usually found on the surface of a household frying pan. The viaduct was guided by a number of rollers placed on the piers, which ensured the deck remained on course for the full duration of the operation. 

The commitment and collaborative approach demonstrated by the Mott MacDonald SYSTRA DJV and the wider Integrated Project Team is inspiring.

Rob Owen, Project Manager, SYSTRA Ltd

Rob Owen, Project Manager at SYSTRA, said: “Once again the design team is extremely proud to see their design brought to life as part of what is a complex and innovative launch phase.

“The commitment and collaborative approach demonstrated by the Mott MacDonald SYSTRA DJV and the wider Integrated Project Team is inspiring, and we look forward to seeing the final section of the east deck being completed later this year, followed by the west deck launches throughout next year.”

Each viaduct is formed of a hollow double-box structure made of weathering steel. The steel boasts a natural protective layer of oxidisation which gives it a characteristic ‘rusty’ appearance and reduces maintenance by eliminating the need for regular repainting. 

Four pairs of concrete piers support the viaducts with the tallest one measuring 9.9m in height. A 4.5m-high parapet will be installed on the side facing Chelmsley Wood to reduce noise and disturbance from passing trains. 

The viaduct was launched with 51 precast slabs already installed on top of the steel structure. This will further reduce the number of road closures in the future, to complete the viaduct deck works. 

Find out more about our work on HS2.