Balfour Beatty VINCI has reached a significant milestone in the construction of HS2, completing the first of several major viaducts at the Delta Junction in North Warwickshire.

This achievement marks a major step forward as work on the high-speed rail line ramps up in the region.

A dedicated team of 40 workers from Balfour Beatty VINCI used an innovative cantilever structure to construct the 472-metre single-track River Tame West Viaduct. The project is notable for being the first time this advanced technique has been used in the UK. The method involves moving concrete segments into place, span-by-span, offering an efficient and flexible approach to construction.

Construction on the viaduct's piers began in 2023, with work on the concrete deck following in early 2024. Over the course of the project, 190 pre-cast concrete segments have been successfully lifted into place using the specialist cantilever system.

The River Tame West Viaduct is part of a larger scheme to create three rail tracks across the region, including a single-track viaduct and a double-track viaduct. Construction is already underway on the double-track viaduct.

Located at the northern end of Delta Junction, these viaducts are an essential part of the HS2 project, which aims to connect London, Birmingham, and the North. The junction will consist of 13 viaducts and more than 10 kilometres of track, designed to carry HS2 over rivers, existing rail lines, local roads and motorways.

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In this location HS2 is also building the single-track River Tame East Viaduct. In addition, two Water Orton Viaducts are being built on either side of the River Tame West Viaducts, making it one of the most complex sections of the HS2 railway.

Used in the UK for the first time, the specialist cantilever method is being used to build nine of the 13 viaducts in Delta Junction, totalling 6,500 metres in length. The process installs pre-cast concrete segments produced at HS2’s nearby factory at Lea Marston.

The two River Tame West Viaducts cross the River Tame near Water Orton and join the Curdworth Box, which will take high speed trains over the existing Birmingham to Derby railway.

Construction of the 20 piers to support the two viaducts started in 2023, with the first spans of the three-track section completed in Spring 2024. This initial phase involved placing the segments onto two 42 metre truss beams, moving them into place with a skidding trolley, and securing them by post-tensioning techniques.

Since then, the giant cantilever structure was built, using a 22-metre-high mast, including temporary post-tensioning cable stays and a 14-metre-high swivel crane.

The crane lifts and installs one concrete segment into place at a time, eventually completing each 45-metre span length. The permanent post-tensioning tendons are then stressed to allow the removal of the temporary cable stays, leaving the permanent structure securely in place. The same process is repeated between each pier until all the spans are complete.

The process was initially developed by Campenon Bernard, later becoming part of VINCI Construction. The mast and the swivel crane deployed on the River Tame West Viaducts are designed and manufactured by the company BERD.

A team of 40 people are currently involved in the operation, and a total of 2,742 concrete segments in total will be moved into place for all nine viaducts using this specialist technique. All the deck segments are due to be in place by late 2026.