Connected Cities, flooding, green infrastructure, London, Water, WSUD

Over the next 35 years, London’s population is estimated to grow by over one third to 11.27 million people in 2050. Not only does this present huge challenges for housing delivery – an additional 16,000 completions per annum to meet the Greater London Authority’s (GLA) target of 42,000 homes a year – but it also raises critical questions about how to deliver the supporting infrastructure that will ensure London remains a great place to live and work.

To inform their response to the mayor’s consultation on the Draft London Infrastructure Plan 2050, the London Assembly Planning Committee convened an expert panel on which I joined Lord Andrew Adonis MP, shadow minister for infrastructure, Jerome Frost of Arup, former head of the Olympic Delivery Authority, and Dr. Dominic Hogg, Chairman of Eunomia Consultants. Chaired by Nicky Gavron AM, the public session provided an opportunity for the committee to quiz the panel on London’s long-term infrastructure needs.

The discussion covered a wide range of infrastructure needs, from low-carbon energy through to enabling digital technologies and supporting the development of a circular economy. I was specifically asked to provide input around future water management and the delivery of green infrastructure. Today, we are faced with a number of challenges, including:

  • An expected shortfall in water supply of 10% by 2025;
  • Demand for an additional 9,000 hectares of accessible green space needed to keep pace with existing standards;
  • A need to support strategic investment in sewer capacity with measures that reduce peak surface flows.

Given this context, a strategic planning approach that integrates water cycle management with green infrastructure delivery is essential.

AECOM developed the UK Water Sensitive Urban Design (WSUD) Scoping Study for not-for-profit CIRIA. We have also undertaken an innovative cost-benefit analysis using green infrastructure as a major component of water management for regeneration areas in Birmingham and Coventry. This work, The Ripple Effect, showed that WSUD can deliver benefits calculated at 7.5 times the value invested.

Recognising the long lead-in time and lifespan of infrastructure, the extended horizon of the Draft Infrastructure Plan to 2050 provides an unprecedented opportunity to set a vision of what infrastructure is needed to maintain London as a leading global city. This long-term thinking allows for critical appraisal of the shorter-term planning, political and regulatory cycles that can constrain the long-term sustainable vision our communities require.

At £1.4tn, the predicted cost of delivering the required infrastructure upgrades is significant. The challenge is to translate the proposed infrastructure plan into a narrative with meaningful outcomes that both the London and wider electorate can connect with. Similarly, there is a need to align thinking around infrastructure delivery with a spatial plan that takes an equally long view and links with the surrounding London Region.

In support of such a vision, AECOM have analysed not only growth in the capital’s 33 boroughs, but also the 94 local authorities within a 90km radius of Central London. Andrew Jones, AECOM’s managing director for Design, Planning + Economics in Europe, Middle East, and Africa, commented: “Limiting the conversation about the housing shortage to the GLA’s borders ignores the 700,000 people commuting into the city every day and the acknowledgment that London is the number one economic driver for the entire South East. To properly manage London’s future growth, we must start looking at London as a metropolis of 20 million people that is economically, socially and culturally connected to the capital. A considered and comprehensive programme of integrated growth strategies from the inner-city through the region will create thriving places and balanced communities, tied together by high-quality environments and efficient, quick transport.”

Along with traditional grey infrastructure, green infrastructure will be a critical thread in this overall fabric. More on the vision for the London Region to come.


Mike HendersonMichael Henderson ( is associate director, sustainability, with AECOM’s Design, Planning + Economics practice in London.

Originally published Nov 12, 2014

Author: Michael Henderson