HS2 engineers have completed the first major phase of launching the Duddeston Junction Viaduct over existing railway lines in Birmingham, beginning a complex operation that will eventually take the structure across six live tracks.
The engineering team has successfully launched the first 170 metres of the viaduct over two freight lines, marking a significant milestone for the Curzon Approaches into Birmingham Curzon Street Station.
Duddeston Junction is the first and longest of five interconnected viaducts forming the Curzon Approaches, which will carry HS2 through Birmingham’s industrial heartlands on the final approach to the city centre terminus.
The 700-metre structure presents a particularly challenging engineering programme because of its location and geometry. It follows a varying horizontal curve while climbing at a three per cent gradient, eventually taking HS2 approximately 12 metres above the existing railway.
Tony Zakaria, HS2’s Senior Project Manager for the Curzon Approaches, 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.
“This final mile stretch of the HS2 route into the city centre is extremely challenging and we’ve worked exceptionally hard, in conjunction with Network Rail, to plan the whole operation with minimum disruption to both passenger and rail freight services.”
Complex operation across six railway lines
The first launch represents the beginning of an operation expected to continue into next summer as the viaduct crosses three freight and three passenger lines.
More than 200 passenger and freight services use the existing railway corridor each day, requiring HS2, Balfour Beatty VINCI (BBV) and Network Rail to carefully coordinate construction around the operational railway.
Preparatory work began in 2023 and included relocating major utilities and dealing with significant ground contamination.
BBV also constructed the Duddeston Mill Road Underbridge, enabling two of the three freight lines to be diverted onto a new bridge and embankment.
Working with Network Rail, the tracks were realigned to create a 20-metre-wide construction corridor between the existing railway lines. This provided the space required to assemble the HS2 viaduct and construct its supporting piers and portals.
Up to 90 engineers and operatives are working within the constrained site, positioned between six live railway lines and a busy industrial estate.
Ross Rendell, Section Manager at Balfour Beatty VINCI, 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 705-metre-long structure is being built inside a narrow space next to a live railway, where it curves above Birmingham’s industrial heartland at an incline. The viaduct also crosses over six railway lines, adding further challenges to its construction. I’m incredibly proud of the way my team has overcome these hurdles, as this huge viaduct continues to take shape.”
Seven spans to be launched across railway
The weathering steel viaduct consists of 14 spans, typically around 55 metres long, with the complete structure weighing up to 6,835 tonnes.
Seven spans will be assembled and progressively launched across the existing railway.
As each span is completed, it is connected to the rear of the structure before the viaduct is pulled forward using a sliding technique. Once the railway has been crossed, the remaining seven spans will be installed by crane on the opposite side.
The completed viaduct will be supported by one abutment, two steel piers, four portals and eight concrete piers.
At more than 700 metres, Duddeston Junction is comfortably the longest structure within the Curzon Approaches, exceeding the approximately 300-metre Curzon 1 viaduct by more than 400 metres.
HS2 and BBV are now working with Network Rail on the next stage, which will involve launching the structure across the passenger railway from December.
John Emery, Senior Sponsor at Network Rail, said: “We’re proud to play our part in enabling the impressive yet complex installation of the Duddeston Junction Viaduct across one of the region’s busiest rail corridors which is needed for our partners at HS2 to construct Britain’s new high-speed railway.
“The striking new structure will eventually span all six lines of the existing railway which carries a mixture of over 200 passenger and freight services daily.
“By working closely with HS2 and adopting innovative engineering solutions where construction affects the existing railway, we’re continuing to minimise disruption to passengers and freight as much as possible.”
Birmingham approaches taking shape
The milestone is the latest sign of progress on HS2 infrastructure across Birmingham.
Once operational, high-speed trains will emerge from Bromford Tunnel before travelling through a cutting at Washwood Heath. The railway will then begin climbing through Saltley on a retaining wall connecting into Duddeston Junction Viaduct.
From there, trains will continue across the Curzon Approaches towards the new Curzon Street Station.
Further work is scheduled around Duddeston over the August bank holiday weekend, when engineers will install the first section of the new Saltley viaduct.
The work will take place between Saturday 29 and Monday 31 August and will affect some existing services through Birmingham, with passengers being advised to check their journeys before travelling.
With the first 170 metres of Duddeston Junction now successfully launched, the focus turns to navigating the most operationally sensitive stages of the programme as the structure advances across one of Birmingham’s busiest railway corridors.
