Four Lines Modernisation

Making four lines fit for the future

We are transforming four of London’s oldest underground lines so that by 2023 passengers will experience a faster, more comfortable journey with more capacity and better reliability.

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Four Lines Modernisation Project summary


Transport for London

Project value

£5.4 bn

Key partners

CPC Project Services

Services provided

Project and programme management, Consultancy


Transport, Rail


UK and Europe

Project timeline

Start date
End date

Project story

With London’s population growing year on year and being set to hit 10 million by 2030, the demands placed on London’s ageing underground network continue to increase.

With our joint venture partner CPC Project Services, we are transforming four of the oldest sections of the London Underground network - the Circle, District, Hammersmith & City and Metropolitan lines. Works include the installation of 51 new signalling rooms and a variety of other upgrades along 161km of track to enable the introduction of new train rolling stock. At the heart of the programme is the installation of a brand new £800m CBTC signalling system, which will allow new rolling stock to run more frequently and faster.

Our role covers two areas, firstly we are reviewing and improving the existing major programme, which has over 4,000 interfaces with other works, to make it more integrated, efficient and value driven. Secondly, we are embedded with Transport for London’s (TfL) client team working on the implementation of the programme and delivering projects on their behalf.

Project stats

£5.4bn programme
1m passengers use these lines every day
4,000 interfaces with other projects
40% of the underground network

Points of note

Leading from the top

Our programme lead is integrated within the 4LM Leadership Team with key accountabilities for managing the 4LM Integrated Programme. We chair leadership hub meetings that aim to maintain the programme momentum by addressing key issues and opportunities with the projects three key stakeholders - London Underground (LUL), Thales and Bombardier Trains.

Simplifying complexity

Over time the control and management structure had grown in complexity in line with the complexity of the programme. Our team took a step back and aligned the control structure with the programme, while simplifying the governance structure. This has allowed the LUL management team to concentrate on managing emerging issues and risks driven by a simplified integrated programme.

Client. Mace. One team

To deliver challenging programmes of this scale requires one highly performing team to be established quickly. With our joint venture partner, from inception we embedded ourselves within the client organisation, to establish the right behaviours, environment and tools to manage this major TfL programme. The Mace team is now a fully embedded and integrated part of the LUL 4LM programme team.