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London Underground 4LM Re-signalling Project

Farnham Re-Signalling The 4LM Re-signalling Scheme is a long term signalling scheme aimed at increasing capacity on the Circle, District, Hammersmith and Metropolitan lines. 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 project is expected to initially run for 6 -18 months with further options thereafter. Unique features of the project include five complex rail junctions, 113 stations and 191 trains, interfacing the system with 4 depots, six sidings (two of them major), and the integration and presentation of existing CCTV and PA systems with a central control centre. 

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.


Volker Rail

Project Value



October 2017 — Ongoing

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

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