Lower Thames Crossing uses Europe's largest tunnel boring machine

Construction has begun on the Lower Thames Crossing, a project that will feature the largest tunnel boring machine (TBM) ever used in Europe. This machine, with a diameter of 16.4 metres, is being built by Herrenknecht and is scheduled to commence operations in 2028. The £11bn project, which started enabling works in March, is set to create a new 23km route connecting Kent and Essex via twin tunnels beneath the River Thames.

The primary objectives of the Lower Thames Crossing are to improve connectivity throughout the South East of England. This includes increasing logistics capacity on the road network, doubling the road capacity across the Thames east of London, and eliminating the significant congestion at the Dartford Crossing. The project is described as transformational due to its scale and its ambitious environmental goals.

Read Next in London Travel News3 min read

A2 and M25 face overnight closures September 14-17

National Highways plans roadworks affecting both carriageways and slip roads during late evening and early morning hours.

Focus on Green Construction

National Highways designated the Lower Thames Crossing as a carbon pathfinder project in 2022, a move that has led to its description as "the UK’s greenest road." Key ambitions include reducing the construction carbon footprint by 70% compared to traditional methods and offsetting the remaining emissions to achieve carbon-neutral construction. This aligns with standards such as PAS 2080. The project has also successfully eliminated diesel from its worksites by utilising electric plant, green hydrogen, and biofuel.

Lower Thames Crossing chief executive officer Matt Palmer stated that the project aims to demonstrate that infrastructure can be delivered sustainably. He noted that in 2022, while other major projects like Hinkley Point C and HS2 were underway, the Lower Thames Crossing was a road project in Essex. To attract skilled contractors and talent, the project needed to adopt a distinctive approach.

Related Borough Coverage4 min read

Engineers Criticise National Highways' Drainage Design Rules

Firms say the Design Palette lacks guidance and contains factual errors, potentially compromising water quality.

The project was the first major UK scheme to have a legally binding carbon footprint limit as part of its Development Consent Order. Carbon considerations played a significant role in the tender evaluation for key delivery partners, including Bouygues Travaux Publics, Murphy Joint Venture (BMJV) for tunnels and approaches, Balfour Beatty for roads north of the Thames, and Skanska for roads in Kent.

Programme director Shaun Pidcock highlighted the importance of early design thinking in establishing green construction practices. Embedding sustainability principles from the project's inception helped to reduce embodied carbon before site activities commenced. The project set an industry target for carbon usage, then aimed to reduce it by 30% below a reference line, inviting delivery partners to bid on this basis.

Early design decisions included opting for a single TBM for the bored tunnels, which reduced the embodied carbon associated with manufacturing and transporting equipment. This also necessitated a smaller scale for associated facilities like the precast segment factory and wastewater treatment plant. Antoine Schwob, BMJV project director for tunnels and approaches, commented that the project had "no other choice than to really push boundaries into delivering low-carbon solutions."

Skanska senior design lead Max Cochrane explained that emphasis has been placed on integrating design choices since the contract began two and a half years ago. Construction methodology and design solutions are now fixed, with detailed design progressing rapidly. Low-carbon design principles have also been applied to key structures, such as a planned footbridge over the A127, with potential for wider application across the road network.

Low Carbon Materials and Plant

The selection of low-carbon materials and plant, including steel, concrete, and machinery, aligns with the project's green design principles. Heidelberg Materials is supplying evoBuild low-carbon concrete, which incorporates up to 70% cement replacement using ground granulated blast furnace slag, and evoZero near-zero cement. Ian Innes, Heidelberg Materials UK major project key account director, noted that reducing cement's carbon impact is a key industry driver.

The project team is collaborating with UK green hydrogen producer GeoPura. In October, a British-made JCB hydrogen-fuelled digger, the first used outside a test environment globally, was deployed for survey work in Kent. The scheme is on track to become the world's largest zero-emissions machinery site, with an estimated 150 zero-emissions machines planned, ranging from 20-tonne diggers to rollers and telehandlers.

Lower Thames Crossing is also working with electric construction machinery manufacturers such as Volvo Construction Equipment. Kent Sahlin, Volvo's global product manager for wheel loaders, confirmed the manufacturer has offered the scheme its A40 electric articulated haulers, capable of carrying 39 tonnes, for large-scale material movements. Volvo's electric range includes smaller articulated haulers, excavators, wheel loaders, material handlers, and trucks.