London Power Tunnels Phase 2: futureproofing the capital’s electricity supply   

Deep beneath London’s streets, a radical transformation is underway – one that will revolutionise how the city powers its future.  

National Grid’s London Power Tunnels Phase 2 (LPT2) is a £1 billion upgrade project helping renew the city’s electricity transmission system.

Designed to boost capacity, strengthen network resilience and meet future demand, this ambitious scheme is rewiring the capital via a network of underground tunnels to ensure a reliable and resilient electricity future for millions of Londoners. 

AECOM was appointed by the HOCHTIEF-MURPHY Joint Venture (HMJV) as lead designer for all civil infrastructure on this project, which involves building 32.5 kilometres of cable tunnels running from Wimbledon to Crayford across south London and incorporating eight deep access shafts and headhouse structures.  

Building an electricity superhighway deep beneath the capital  

As London’s population grows, so does its electricity demand. Coupled with the shift to renewable energy, a flexible, resilient and high-capacity transmission system is essential. 

LPT2 is addressing this by replacing aging circuits with new underground tunnels. These tunnels span seven boroughs and will house high-voltage transmission cables, ensuring the network is fit to meet future demand.  

By placing cables underground, LPT2 will not only boost capacity but also allow for future upgrades and maintenance with minimum disruption to traffic, residents and businesses. 

We are delivering most of the civil infrastructure on LPT2, including the design of tunnels and shafts as well as the full, detailed design of all headhouses including architecture, structures, civils and landscaping. 

As part of the project, eight new shafts – up to 50 metres deep – have been excavated along the 32.5-kilometre tunnel route. Our long-standing expertise in tunnelling and knowledge of local geography has enabled us to anticipate and mitigate challenges, including navigating challenging ground conditions and value-engineering the designs. 

One of the first schemes to be delivered to Project 13 principles 

To deliver this critically important infrastructure project at the scale and pace required, National Grid took an industry-leading approach.  

Instead of using traditional transactional contractual arrangements, National Grid was an early adopter of the Project 13 enterprise model, in which all parties – clients, designers and contractors – work as one team.  

This model incentivises collaboration by placing all partners on the same contracts. Key Performance Indicators (KPIs), Enterprise Performance Measures (EPMs) and Milestone Enterprise Performance Measures (MEPMs) drive the process, linking rewards and penalties directly to project performance.  

The performance of each partner impacts the entire enterprise, ensuring that everyone is fully invested in the project’s success from start to finish. It also embraced desired project outcomes around elements of delivery such as carbon reduction, use of local and trainee workforce, and community volunteering. 

LPT2 is one of the first large scale infrastructure projects to be delivered using Project 13 and has done so with demonstrable success. 

All design packages delivered on time 

Working as contractor’s designer, we delivered every single design package on or ahead of time. In addition, the HMJV completed all of their sectional completion handovers on or ahead of time.  This was despite the unprecedented challenge of working through the coronavirus pandemic.  

Our progressive assurance process – which was previously applied on the Thames Tideway Tunnel and tailored to LPT2 – was a key factor in making sure that HMJV hit the project milestones and that National Grid were taken on the design journey and were able to shape the outcomes they required. By involving all parties in regular interdisciplinary design reviews, we aligned design objectives, caught potential issues early, and reduced the risk of errors and rework.  

Timely delivery was also thanks to the longstanding positive working relationships between the contractor and designers, all of whom were invested in the project’s ultimate success, supplemented by the Project 13 enterprise model adopted by National Grid.  

Cutting carbon with the world’s largest single pour of Earth-Friendly Concrete  

Sustainability was an important aspect of LPT2, and one of its most notable innovations was the use of Earth Friendly Concrete (EFC) – a low-carbon, cement-free alternative to standard concrete.  

Although EFC has previously been used in Australia, its application in the UK required extensive testing to determine its suitability for this project.   

We played a crucial role in working with HMJV to specify testing criteria and analyse the results of these tests and field trials, helping to secure buy-in from the client and the supply chain. Following successful trials, EFC was approved for use in permanent works – marking a major milestone for its use in large-scale permanent construction.  

This culminated in world’s largest ever continuous pour of EFC in April 2023, cutting an estimated 82 tonnes of CO2 from the project’s embodied carbon.  

A model of collaboration and success that’s accelerating the energy transition  

LPT2 is a prime example of how collaboration and strong partnerships between the end-client, designers and contractors can help deliver critical infrastructure on time and within budget.   

But that’s not the London Power Tunnels’ only legacy. By increasing transmission capacity, the new tunnels will ensure that Londoners will be powered by a secure and reliable energy network for decades to come.