Week delay on Colne Valley Viaduct job after contractor spots misalignment

Work on HS2’s Colne Valley Viaduct has been set back a week after a misalignment was spotted within the most recently completed span. 

A recent letter from Align, the joint venture responsible for the 3.4km bridge in Hillingdon, warned local residents about night-time noise this week as concrete is broken out to allow engineers to fix the problem. 

Until these “urgent remedial works” are carried out, the launching girder which is constructing the viaduct chunk by chunk will be unable to make any progress over the Grand Union Canal. 

Colne Valley Viaduct launching girder at the Colne Valley Viaduct site.

The Align JV includes Bouygues and Sir Robert McAlpine

“We need to repeat cable tensioning work on the most recently completed span of the Colne Valley viaduct,” an HS2 spokesperson explained. 

“To do this, first we must drill out the span’s concrete join. Work began on 19 February.  

“We hope to complete it this week, and then construction work will continue as planned.” 

>> In pictures: how Align JV is building the UK’s longest rail bridge, one piece at a time

>> The longest job: Building the Colne Valley viaduct

More than 700 of the 1,000 precast deck segments required to complete the viaduct have so far been launched using HS2 Ltd’s 700-tonne launching girder. 

The cantilever is constructed using precast deck segments that are erected either side of the pier, with the final 20cm join that connects adjacent cantilevers being cast on site, and the adjacent cantilevers are then post tensioned together to form the viaduct.    

It is this 20cm join that will need to be broken out to carry out remediation inside the structure. 

Align JV, which includes Bouygues and Sir Robert Mcalpine, has offered to provide alternative accommodation to those affected by the night works this week.