Balfour Beatty Vinci has just pushed the first 170m section of the 700m-long Duddeston Junction Viaduct over two busy freight lines.

The move marks the start of a major engineering operation to span six live tracks, including three freight and three passenger lines.

Work to complete the crossing is due to run until next summer, with the next launch phase over the passenger railway scheduled to begin in December.

Duddeston Junction is the longest of five interconnected viaducts making up the Curzon Approaches into the city centre.

The weathering steel structure is made up of 14 spans of around 55m and will weigh up to 6,835 tonnes when complete.

Seven spans will be assembled behind the launch point and progressively slid forward across the existing railway.

The remaining seven spans will then be lifted into place by crane once the structure has cleared the live tracks.

The engineering challenge is made tougher by the viaduct’s changing horizontal curve and 3% gradient, which sees it climb to around 12m above the existing railway.

Up to 90 engineers and operatives are working on the heavily constrained site.

HS2 senior project manager Tony Zakaria said: “Launching the fifth and final viaduct on the Curzon Approaches is a clear sign of the progress we are making to bring high speed rail to Birmingham.”

BBV section manager Ross Rendell said: “Duddeston Junction Viaduct is hugely complex and a key section of the HS2 route that will take trains in and out of Curzon Street Station.”

The viaduct will be supported by one abutment, two steel piers, four portals and eight concrete piers.