The four lines make up 40% of the tube network with around 1 million journeys each day, with the new signalling works allowing the operation of 32 trains per hour with a 33% increase in peak hour capacity.

The 4LM Re-signalling Scheme is a long term signalling scheme aimed at increasing capacity on the Circle, District, Hammersmith and Metropolitan lines.

The aging infrastructure presents additional challenges: parts of it are 150 years old, the cabling is ancient by modern standards, and one-of-a-kind legacy systems take time to understand. Some of the technology due for replacement is around 50 years old. It all presents a challenging task that needs to be done quickly and accurately. The network has been divided into 14 ‘Migration Areas’ for a carefully phased rollout. The first five of these are centred on the Circle line, which is the track which carries the most passengers. The improvements to the Circle line will go live at the end of 2019, bringing faster, more frequent trains to the travelling public years ahead of the final completion date.


To date RTIS has supported Volker Rail on this project with IRSE signalling teams with zero reported accidents or RIDDORS. Installation works have been conducted during day and night time shift patterns installing 4ft equipment, signalling survey works, fabrication of signalling assets, SER installations and various other signalling works.



Activities Undertaken

  • Installation of Axle Counters
  • Installation and Termination in SER’s
  • Installation of new Anchor posts
  • Cable Diversion works and modifications to new location cabinets & REBs
  • Installation & Termination of new disconnection boxes
  • Installation & Termination of earth cables
  • Installation of TAG equipment
  • Signalling surveying


Volker Rail

Project value



October 2017 — November 2018