Connect: keeping London moving under, and over, ground for 20 years

Two million people rely on London’s Underground to get to work, return home or make appointments on time and safely. They can take it for granted that trains can move and stations are open. But all of this is only made possible by a radio communications system which works behind the scenes day and night to connect key staff.

Underground connectivity

Every driver on every train and every station on the underground is connected by a communication network, aptly named Connect. If that connection is broken, then trains don’t leave platforms and stations have to close. Frustrating though this would be for passengers, anything less would put lives at risk.

Over the past 20 years London Underground has worked with global transport technology company Thales to build, install and run Connect, a robust, unified radio communication system that works above and below ground. Teams installed Connect, replacing base stations and controls throughout the nearly 250 miles of track and 270 stations on the network, without interrupting services.

Gary Groves is Thales’s Contract Performance Manager for the Connect Contract. Thales and Transport for London (TfL) staff work side by side at the Connect Network Management Centre.

“If the network fails, London Underground could stop the train running and close stations until it’s sorted out,” said Gary. “It’s crucial that Connect is kept running and we make sure it provides 100% coverage across every line, 100% of the time.”

However, the fact that most of the passengers making more than one billion tube journeys each year are unaware of Connect shows how successful the partnership has been.

Greater safety for Londoners and visitors

Connect offers a better service to passengers and a safer one. Not only are drivers, station staff, and line controllers constantly in communication, but the system is robust enough for Airwave, the national operator for emergency services radio communications, to piggyback on.

This allows emergency service personnel to use their radios underground and remain in contact with controllers on the surface, a capability which was frequently missing in the immediate aftermath of the 7/7 bombings.

How Connect works

Thales’s Connect system provides the radio, transmission and operational CCTV communications technology that TfL staff need to communicate on the London Underground.

Radio signals don’t travel far underground but Connect uses a secure, closed network of “leaky feeder” cables which run from Core Sites via base stations along every tunnel. These carry radio signals which are transmitted through tiny holes drilled along the length of its outer cover. Above ground the system operates over a combination of cables and antennae.


The various ageing systems replaced by Connect would not have coped with the pressures of increased night and weekend services, events such as the London Olympics and New Year’s Eve, or emergencies as maintenance windows have become squeezed and greater use puts more strain on equipment.

Thales operates a one-stop shop for Connect which responds quickly to repairs and maintenance needs. The joint venture also keeps the system on a roadmap for future developments.

“With a technology roadmap in place we are futureproofing Connect across the network,” said Gary.

“An ongoing upgrade is due finishing in 2020 and Connect can be easily upgradable by London Underground.”

All change?

Connect has been in service for more than 10 years, and the PFI agreement between London Underground and Thales’s Ground Transportation Systems business expired in November. However, a new four-year contract has been signed, with an option for an additional three years.

“The end of the contract was marked with a formal handover of the network to London Underground,” said Gary. “But the public should see no difference in service. Our work should go unnoticed.”

So long as trains run on time, stations can operate and millions of Londoners reach their destinations safely and on time, then London Underground’s partnership with Thales and the Connect network are indeed doing their job.

Read more about Thales in the UK’s work in ground transport here.