HS2 Ltd has celebrated the installation of its final viaduct across the M6 as the second structure has been put in place near Chelmsley Wood.
The final section of the 4750-tonne structure was launched above the north and southbound carriageway (junction 4/4a) using giant hydraulic jacks while vehicles travelled below – a process which aimed to minimise disruption for motorists.
This milestone renders both M6 South viaducts structurally complete, with the east deck, which will carry high-speed trains towards HS2’s two London stations – Old Oak Common and Euston – having previously been completed in 2025, whilst the west deck – the structure near Chelsmley Wood that will carry trains towards Curzon Street Station in Birmingham city centre, as well as destinations in the north, including Manchester, Liverpool and Glasgow – having been completed this weekend (24 October).
Both parallel structures, which stand 100 millimetres apart, were constructed using weathering steel, and are supported by a series of concrete piers, as well as raised embankments, which will soon be formed on either side of the viaducts.
Whilst the structures are both 320 metres in length, they were assembled and launched differently due to constraints of the site. The west deck was launched in four incremental stages, and the east deck in three, and, for each launch, additional steel sections were added to the rear of the structure before the whole deck was propelled forward using strand jacks. By the final launch, the weight of the steel deck was fully supported on concrete piers at either side of the carriageway, allowing the ‘last push’ to be safely executed while maintaining traffic flows.
Ian Clarke, Senior Project Manager at HS2 Ltd said:These viaducts straddle some of the busiest sections of motorway in the country, which is why we adopt innovative techniques that allow construction to continue without closing the carriageway whenever we can.
We have made great progress this year and I thank motorists and local communities for their patience.
In 2027, HS2’s motorway construction programme will centre around the triple box – a rail-over-road structure that will carry four HS2 railway tracks over the M42 near Coleshill.
