UK: HS2 has launched the first 170 metres of the Duddeston Junction Viaduct over two freight tracks in Birmingham, beginning a multi-stage operation that will eventually cross six working railway lines.

Duddeston Junction Viaduct under construction beside the live railway in Birmingham
Duddeston Junction Viaduct under construction in Birmingham. Photo: Bradley Simmons / HS2 Ltd.

Seven of the viaduct’s 14 spans will be assembled and launched across three freight and three passenger lines, according to HS2. The remaining seven will be lifted into place by crane on the opposite side. Work over the passenger lines is scheduled to begin in December, with the full operation expected to conclude in summer 2027.

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Why the structure is built two ways

Incremental launching reduces the amount of crane work and temporary support required directly above an operational railway. Each completed span is added to the rear before the assembled section is pulled forward using a controlled slide system.

HS2 says seven spans must be launched to cross the six existing railway lines. Once that section has cleared the railway, the seven remaining spans will be lifted and lowered into position by crane on the opposite side. The release does not provide a cost comparison between the two methods.

Element Figure
Length About 700 m
Spans 14, each about 55 m
Cumulative weight of steel spans Up to 6,835 tonnes
Height above existing tracks 12 m
Gradient 3%
Substructure One abutment, two steel piers, four portals, eight concrete piers

Two features make this launch harder than a standard one. The alignment follows a varying horizontal curve rather than a straight line, requiring tighter alignment control as the structure is pushed. It also climbs at three percent from ground level to 12 metres above the tracks, making the launch an uphill operation.

Up to 90 engineers and operatives are working on the site, which is hemmed in between the live railway and Birmingham’s industrial fabric.

The last of five

Duddeston Junction is the first structure on the approach from the east and the last of the five Curzon Approaches viaducts to be launched. The others are Curzon 1, Curzon 2, Lawley Middleway and Curzon 3, together forming just under a mile of elevated railway into Birmingham Curzon Street.

Curzon 2, the tallest structure on the HS2 project, was slid 180 metres into position earlier this year in a three-stage operation that included a weekend closure of the Cross City line. The first 112-metre section of Lawley Middleway was launched over part of the city’s ring road in August 2025. Curzon 3 is where the alignment fans out from a single deck into four separate decks to reach the station’s seven platforms.

HS2 and Network Rail have asked passengers to check journeys over the August bank holiday weekend, when separate work near Duddeston will install the first section of the replacement Saltley Viaduct.

One figure that does not agree with itself

HS2’s own project page for the Curzon Street approach viaducts describes Duddeston Junction as a 375-metre structure. The release issued this week describes it as about 700 metres long, while the contractor quoted in it gives a figure of 705 metres. Construction Enquirer also reports about 700 metres across 14 spans of roughly 55 metres each.

Seven launched spans of roughly 55 metres would total about 385 metres, suggesting that the 375-metre figure may refer to the section crossing the operational railway rather than the complete 14-span viaduct. But HS2’s project page, updated on Aug. 19, describes 375 metres as the length of the structure itself, leaving the discrepancy unresolved.

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