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Four Lines Modernisation

Services: Planning & Controls

Value: 5.54 Billion

Sector: Rail

Transforming the Circle, District, Hammersmith & City and Metropolitan lines. When the work is completed in 2023, increased capacity and boosted reliability will make journeys faster and more comfortable.

New trains

A fleet of 192 modern, air-conditioned, walk-through S-stock trains are now in operation across the Circle, Hammersmith & City, District and Metropolitan lines.

These trains are longer and more spacious than the old trains they replaced. The train doors are also bigger, creating extra space for more people to get on and off at stations. This speeds up journeys.

The new trains are walk-through with air conditioning, as well as improved audio and visual information, dedicated wheelchair spaces and colour contrasting interiors.

New track and drainage

By replacing old and worn out track and points your journeys will be quieter and smoother. Coupled with brand new drainage systems, they will be more reliable during bad weather.

Better drainage means that the track is much less likely to flood, reducing delays to journeys because of signal failures, as well as fewer closures for maintenance and repair works.

New signalling system

Work to install a new signalling and control system began in summer 2016. This will eventually allow the trains to be driven automatically, with a train operator in the cab to open and close the doors. The train operator will be responsible for managing customer information and safety.

Similar technology introduced in recent years on the Jubilee and Northern lines improved performance. The new signalling system allows trains to be run closer together, meaning a more frequent service and shorter waiting times, allowing more people to be carried. This new technology will enable us to reduce delays and improve reliability.

The programme will allow us to operate 32 trains per hour, a 33% increase in peak-hour capacity. Installation work will require some line closures.


  • A new fleet of air-conditioned trains, with brighter more spacious interiors, low floors and dedicated spaces for wheelchair users, CCTV and other improved features
  • Space for more customers
  • Faster journeys and reduced waiting times
  • Fewer delays as safe but obsolete equipment – dating back to the 1920s in some places – is replaced with modern, computerised signalling and control systems
  • Better live customer information on platforms and to smart devices


  • 2017: new signalling starts to be installed on the first section. Trains begin to be fitted with new on-board signalling equipment
  • 2018: new Hammersmith Service Control Centre ready for staff training. First section of new signalling is complete. Improved reliability and customer information on sections of Circle and Hammersmith & City lines
  • 2019: Hammersmith Service Control Centre opens
  • 2020: new signalling complete across central London
  • 2021: initial improvements to journey times in central London and to Barking – up to 30 trains per hour during the peak
  • 2022: final section of new signalling system completed. Trains increased to 32 per hour in central London and to Barking during peak times
  • 2023: more trains on the Metropolitan line at peak times. Increased services on the busiest sections and better customer information

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