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, Consult


Transport, Rail


UK and Europe

Project timeline

Start date

Project story

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

Alongside 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 communications-based train control (CBTC) signalling system, which will allow new rolling stock to run faster and more regularly, with up to 32 trains per hour for Londoners during peak times.

Our role spans the entire programme of works, with our team providing strategic advice on transformational change and task prioritisation. Through this role, we have been able to influence and improve discrete and challenging components of the programme which, combined, have over 4,000 interfaces with other works. Our approach has made the programme more integrated, driving better efficiency and value as a result.

Fundamental to this successful approach is our close working relationship with the Transport for London (TfL) client team. We are embedded into the team, working side-by-side with our TfL colleagues, sharing our programme management expertise with them, and taking joint responsibility for the implementation and delivery of complex projects that are essential to unlocking benefits for millions of Londoners. 

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

We hold key accountabilities for managing the 4LM Integrated Programme, providing senior leadership on maintaining programme momentum and addressing issues and opportunities with key stakeholders. We lead by example, driven by our commitment to quality service for our clients and delivering on our promises. 

Knowledge share

We run training sessions for the client, drawing on our wealth of programme management expertise to promote the adoption of best-practice methods across the entire 4LM team. In addition to targeted training sessions, being embedded with the client provides us with an environment that allows us to organically transfer knowledge on a daily basis.

Client. Mace. One team

Delivering challenging programmes of this scale requires a highly performing team, drawn from different specialisms but working together to achieve the same goal. From the very outset, we worked with our joint venture partner to embedded ourselves within the client organisation, establish the right behaviours, and create a collaborative environment to manage this major TfL programme. The Mace team is now a fully embedded and integrated part of the LUL 4LM programme team.