HS2 – N1 N2 – Delta Junction

HS2 is a new high-speed rail line that will be the backbone of the UK’s rail network.

In April 2020 BBV JV (comprising Balfour Beatty Group Ltd, VINCI Construction Grands Projets, VINCI Construction UK Ltd, VINCI Construction Terrassement) was awarded Contracts N1 and N2 of the High Speed II project.

The Delta Junction section is situated to the east of Birmingham and surrounds the major highway junction between the M6 and the M42 and includes a mainline section, the North Chord and the Birmingham Spur, approximately 15km in length.

More than 50% of the structures within ‘Area North’, are located here and comprise 13 earthworks assets including retaining walls, 17 viaducts, 8 structures and a tunnel portal as well as composite viaducts similar to the M42/M6 link motorway, low viaducts and box structures spanning motorways, roads and Network Rail lines as well as overbridges, underbridges, flyovers, diveunders and a footbridges.

This section of HS2 will enable trains to travel between London, an Interchange Station in Solihull, and Birmingham Curzon Street Station. More than 8.7 miles (14km) of track will be built in this area, crossing over highways, streets, conventional rail lines and rivers. The M42/M6 link viaducts – the two parallel viaducts that cross these roads – were the first Delta Junction structures to be installed, with the final of four viaduct deck pushes completed in September 2024. 

Given the volume of structures, earthworks form a substantial element of works, including more than five million cubic metres of material to be moved with significant ground improvement works.

Understandably, such a large project, with multiple interfaces and the risk of impacting the operation of existing adjacent infrastructure, would require a complex instrumentation and monitoring solution to manage construction related risk.

In 2022, Sixense, in joint venture with Murphy Geospatial Services, were awarded the construction monitoring package for the project. The scope included the supply, installation and monitoring of manual & automatic instrumentation and monitoring across several assets.

The significant quantity of instrumentation installed on site necessitated the attendance of a dedicated Maintenance Team, ensuring the numerous instruments (just some of which are listed below) remain operational and within calibration throughout the construction process.

At the start of 2025 we are approximately half way through delivering the project. The main challenge on the Delta section of the project is the significant distance between different assets and the necessity to coordinate with numerous site teams to ensure installation and data delivery to the client on time and in accordance with the HS2 specification.

All data is stored and visualised within Sixense’s Beyond Monitoring Software, a system capable of accomodating and managing the more than 1,000,000 data values receieved each day from the site instrumentation.