Surface Tension: Underground London’s impact on the world above

On 26th November, Future of London held the third event in our London 2050 series, Surface Tension: Underground London’s impact on the world above. This half-day conference was kindly sponsored by Arup, and brought together public- and private-sector planners, transport experts, engineers and archaeologists to discuss best practice in managing underground infrastructure projects.

With some of the oldest tunnels, sewers and underground railways in the world, London’s subsurface infrastructure presents a minefield for new developments, both above- and below-ground. The Lee Tunnel drops down 80 metres to avoid existing infrastructure, while Crossrail’s tunnels have to weave through 42 earlier tunnels and pipes; future projects will be even more complex.

Building and upgrading London’s physical infrastructure is not just an engineering challenge; the social impact of works is a crucial concern for local authorities: communities around project sites often suffer from noise and disruption for months at a time, and the eventual benefits might not be readily apparent to those affected since they are often intangible or spread across a wide population.

surface tension plenary

These physical and social considerations were discussed in relation to London’s long-term infrastructure needs and ongoing projects. Throughout the afternoon, speakers addressed three key questions:

  • What’s the greatest threat lurking underground?
  • How do we balance the greater good with local impact?
  • What will it take to make above/belowground projects run better?

Many common themes emerged from speakers’ experiences on projects such as Nine Elms, TfL station upgrades and Crossrail, which are summarised below.

Planning and governance

Infrastructure planning and delivery is a slow process, often taking decades for large projects, and far longer than the traditional four- or five-year electoral cycle. Speakers expressed frustration that projects could not be delivered faster, and said the infrastructure planning process needs updating. However, many saw London as setting a good example of long-term infrastructure planning (compared to national policy), for example through the development of the London Infrastructure Plan 2050.

Current processes can also impede projects at delivery level – for example, on large sites it can be difficult to strategically provide utilities in a way that is fair (e.g. early developments pay for infrastructure costs while later ones get a free ride). Nine Elms on the South Bank has set up a special purpose vehicle to act as a single client representing ten developers, so it can work strategically with utilities providers.

Several speakers expressed the need for infrastructure projects to be linked to the broader needs and priorities of their areas, such as through urban realm improvements or integration into local regeneration plans. These should be individual to each area and project – in Whitechapel, a supplementary planning document was drawn up to help guide change accelerated by Crossrail.

Consultation and community engagement

With infrastructure projects getting ever larger, disruption for local residents and business can last months or even years. Proactive consultation at an early stage can inform mitigation strategies and reduce complaints further down the line.

Ongoing efforts to inform those affected by disruption about what is being done – and why – often go a long way towards reducing complaints. In Whitechapel, LB Tower Hamlets employed community liaison officers for each worksite to mediate between locals and Crossrail.

Sharing information internally can also help to reduce disruption through better planning. LB Southwark moved responsibility for all public consultations to a single specialist team. This has allowed for relevant information gathered on one project to inform other projects and carry over lessons learned.

All agreed that consultation methods have improved significantly in recent projects. Still, Duncan Brown of LB Tower Hamlets called for greater efforts to seek views from those who traditionally don’t respond to consultations or engage in the political process, especially as these groups are often among the worst affected.

Project management

With large projects often involving multiple sites and contractors, clear communication was highlighted as an essential feature of successful projects. Tower Hamlets council appointed a project director to act as the single point of contact for Crossrail works in Whitechapel. In the Vauxhall, Nine Elms and Battersea Opportunity Area (VNEB), project organisation Nine Elms on the South Bank set up working groups involving local planning and transport authorities, developers and utilities providers to produce strategic plans and avoid duplication of effort.

Engineering and construction challenges

Knowledge of much existing infrastructure can often be vague or incomplete, especially for pipes and cables laid up to 150 years ago. Surveys are therefore essential to establish exactly what lies below ground and to prevent any damage and delays.

While unexpected disruption to the surrounding area can never be fully avoided, having plans in place can help mitigate the effects.

At the same time, data sharing between projects can reduce the need for invasive surveys, providing a pool of data on what exists belowground for subsequent developments to draw on.


With relatively little of London’s ancient heritage visible, it’s important to record archaeological finds discovered while excavating. While archaeological finds often cause some delay, they represent a one-off chance to record historical knowledge that would otherwise be lost (one example is 19th century goods yards uncovered by Crossrail excavations in the Royal Docks). Clear policies on how to treat finds and good communications with site and project managers can reduce delays and costs incurred.

Listed buildings can also be put at risk by nearby construction. At Bank station, Alan Baxter & Associates have made plans for protecting nearby heritage buildings whilst works are carried out, with provisions to accommodate day-to-day use of the buildings. As with archaeological finds, assigning responsibility for risk in advance can reduce delays should any problems occur down the line.

surface tension tim chapman 2

Speaking at the conference were:

  • Bob Bennett, Crossrail Project Director, LB Tower Hamlets
  • Duncan Brown, Strategic Project Manager, Whitechapel Vision Delivery Team, LB Tower Hamlets
  • Jay Carver, Project Archaeologist for Crossrail and MD, 4AD Consulting
  • Tim Chapman, Director, Infrastructure Design Group, Arup
  • James Eagles, Strategic Project Manager, Nine Elms on the South Bank
  • Gareth Epps, Community Relations Policy Manager, Crossrail
  • William Filmer-Sankey, Partner, Conservation, Alan Baxter & Associates
  • Mel Gardner, Technical Director, Rails & Tunnels
  • Liane Hartley, Director, Mend
  • Eleanor Kelly, Chief Executive, LB Southwark
  • Chris Porter, Transport Planning Manager, Transport for London
  • Joanna Rowelle, Associate Director, Planning, Arup
  • Daniel Zwetsloot, Structural Engineer, Alan Baxter & Associates

Podcasts and slides:



Bank station upgrade case study


Planning breakout session


Mitigation breakout session


Future of London’s work in the London 2050 series also includes the following:

We would like to thank Arup for sponsoring this event:

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