National Grid London Cable Replacement Programme Phase 1 (c) Thomas Graham; National Grid London Cable Replacement Programme Phase 1 (c) Thomas Graham;

London Power Tunnels, London

How do you upgrade 180km of power cables without disrupting the busy city above?

The London Power Tunnels (LPT) Programme is the biggest upgrade to the national electricity transmission system since its construction in the 1960s. This £1bn National Grid-led project aims to rewire the capital in order to meet increasing electricity demand. Over an eight-year period, 32km of tunnels will be constructed, 180km of 400kv cables installed, two new substations will be built and major upgrades to a further four substations will be completed.

During the project’s development, we undertook a validation review. Our findings recognised that without a central guiding and coordinating function, there was significant risk to the LPT’s success. There was also a danger that decisions would be made in the interests of the individual projects, rather than the programme as a whole.

We recommended establishing a Programme Management Office (PMO) that would act as a central hub for the programme, with the thirteen individual projects being coordinated through it.

Project Summary


32km of tunnels

8-year programme of works

£1bnbudget

An integrated team

The primary function of the PMO was to provide strategic advice to the National Grid’s senior management team, whilst aligning the individual project deliverables to meet programme requirements. 

From the outset, the creation and setup of the PMO was sponsored by the NG Programme Director. In order to avoid building up a sense of antipathy, the PMO aimed to get buy-in and acceptance from all stakeholders. This was the biggest challenge as the PMO we had to overcome. We helped NG develop its delivery model for large multi-disciplinary programmes. This required close levels of integration so we encouraged contractors to familiarise themselves with the tools and processes, to enable them to work in unison.

National Grid London Cable Replacement Programme Phase 1 (c) Thomas Graham National Grid London Cable Replacement Programme Phase 1 (c) Thomas Graham
The programme included constructing 12 shafts and head houses.

I value the best practice approach Arup has applied to establish the PMO for the £1bn London Power Tunnel Programme. The processes are being actively and successfully used on this major capital programme ” David Luetchford

Resolving issues

We built close relationships with all the key contractor personnel and local operations. This was achieved through providing improved interaction between parties in resolving issues and the development of the PMO Charter, systems and maintenance teams. We also instigated a client-only “site leads” meeting, bringing together all decision-makers for the purpose of resolving higher level issues. This approach allowed the PMO to implement robust controls, with appropriate support, analysis and recommendations, without taking away accountability from the Project Managers.

A strategic service

Our goal was for all stakeholders in the PMO to view it as a strategic, value adding service, and not an administration function adding an unnecessary layer of process and bureaucracy. 

The programme is now complete, having been delivered approximately six months early and over £50m below the budget approved by the NG board. As a result of this success, many of the tools and processes established on London Power Tunnels are now included in the way NG delivers projects.