London’s transport authority detailed a plan to roll out 4G across the city’s underground rail network by the end of 2024, allowing operators to deliver uninterrupted mobile services on the mass transit system for the first time.

In a statement Transport for London announced a 20-year contract had been awarded to BAI Communications to deliver the neutral host network on its London Underground system.

Once complete the network will be 5G-ready and requires 2,000km of cabling to deliver. It will provide a signal in tunnels, on platforms and within stations.

The vast majority of the city-wide underground system has no mobile connectivity, with only segments above ground and parts of the Jubilee Line currently offering 4G, the latter as the result of a trial deployment started in 2020.

A number of stations also offer Wi-Fi on platforms for customers of specific operators following a deployment by Virgin Media started in 2012.

Alongside in-train mobile connectivity, the infrastructure installed in tunnels will be used to improve fibre connectivity above ground accessible to residential areas, businesses and for IoT deployments.

BAI Communications UK CEO Billy D’Arcy estimated the company would spend more than £1 billion on this, and related projects in London during the 20-year contract.