Balfour Beatty VINCI Completes 2.4km HS2 Coleshill Viaduct Decks UK

Balfour Beatty VINCI Completes Deck Assembly on HS2 Coleshill Viaducts

Balfour Beatty VINCI (BBV), the main works contractor for HS2 Ltd in the Midlands, has completed the deck assembly for the 2.4km Coleshill viaducts in Warwickshire, United Kingdom. The milestone, achieved over a two-and-a-half-year period, involved the installation of 1,024 pre-cast concrete segments. These structures form a key component of the new high-speed railway’s Delta Junction east of Birmingham.

Engineering and Construction Details

The Coleshill East and West viaducts constitute the southern part of the Delta Junction, an interchange designed to route high-speed trains over the M6 and M42 motorways, local roads, existing railways, and the floodplain of the River Cole. The junction’s design includes four separate viaducts. Two parallel viaduct spans will carry the four-track mainline, while two narrower viaducts will carry single tracks for services connecting to the new Birmingham Curzon Street station.

The structures are supported by 54 reinforced concrete piers, each built to a height of up to 12m. The decks were assembled using 1,024 individual concrete segments manufactured at a purpose-built facility in Kingsbury. The central, 22m wide mainline deck is composed of two rows of 11m wide segments, each weighing 60 tonnes. The two single-track viaducts for the Birmingham branch are made from single rows of smaller, 44-tonne segments.

BBV employed a cantilever construction process for the installation. Each segment was lifted into position and supported by temporary steel cables until a full span between piers was formed. Following the completion of each span, permanent post-tensioned cables were installed within the hollow core of the viaduct to provide structural strength.

Project Management and Market Context

The completion of the viaduct decks is a structural milestone for the HS2 project, which aims to increase rail capacity between London and Birmingham and free up space on the existing West Coast Main Line for more freight and local passenger services. This segment of the project connects the main north-south route with the spur into central Birmingham, making the Delta Junction strategically critical for the operational design of the network.

The project is proceeding amid difficult conditions for the UK construction sector. Data indicates economic volatility and financial pressure on contractors, with some firms reporting reduced profitability. Furthermore, other public infrastructure projects are facing scrutiny over cost escalation; for example, the planned North West Relief Road in Shropshire is considered unaffordable after its projected cost increased from £74.2m to £162.4m over six years. This broader industry pressure on budgets aligns with the management approach now being implemented on HS2.

HS2 Ltd Chief Executive Mark Wild is leading a reset of the entire project to ensure the remaining sections of the 140-mile route are delivered with a focus on efficiency and cost control. The successful application of off-site manufacturing and modular assembly on the Coleshill viaducts provides a model for standardised construction that can support this objective.

Next Steps

With the deck segments now installed, construction teams will focus on finishing works, including the installation of kerbs and parapets along the 2.4km length of the viaducts. Work continues across the entire London to Birmingham route under the revised project management framework.