All Change for the Brighton Line … as O2 Joins Cellnex Train Connectivity Project

Telecoms infrastructure giant Cellnex has today signed O2 to the Brighton Main Line (BML) connectivity project. The collaboration will see the mobile operator access Cellnex UK’s neutral host infrastructure along the route. The BML Project is enabling the phased rollout of high-speed mobile connectivity, including 5G, to customers across the train line over the coming months.

Cellnex and O2 were keen to point out that the agreement also covers major train commuter hubs en route, including London Victoria, London Bridge, and Clapham Junction. Three years ago, Cellnex signed a similar collaboration agreement with Three UK.

Work on the BML project began in 2021 when Cellnex signed a 25-year contract with Network Rail. The mast supplier’s task is to bring seamless connectivity to the entirety of the 108km Brighton line. This has proven no easy feat as the route is notoriously tricky to cover, strewn as it is with deep cuttings and tunnels, as well as being blessed/cursed with many fine Victorian stations – great to look at but not great for coverage or mast-siting.

Once completed, Cellnex reports that the shared infrastructure will deliver high speed connectivity across 99% of the line. Thus as the company puts it “drastically reducing historical not-spots and ensuring passengers enjoy reliable calls, uninterrupted streaming and stable app performance throughout their journey.”

The Brighton Main Line is one of the UK’s highest-density rail routes linking London, Gatwick Airport and the South Coast and is used by Thameslink, Southern, Gatwick Express, Great Western Railway and London Overground Services. In total, it accounts for 1,700 daily train movements, serving over 300,000 passengers every weekday, including around 50,000 travelling to and from Gatwick Airport.

New indoor coverage solutions will also be deployed at three of the most important London stations, London Victoria, London Bridge, and Clapham Junction, which account for approximately 20% of railway passenger traffic to and from the capital.

The three-year build programme has, so far, seen more than 129,000 working hours delivered on the line side and at stations. The infrastructure deployed by Cellnex includes 130km of high-capacity fibre, four Base Station Hotels to host MNO equipment, 39 Distributed Antenna Systems (DAS) within tunnels and along trackside locations, a dedicated station DAS at London Bridge, London Victoria and Clapham Junction, and 16 macro sites along the railway route.

Students of the history of WiFi on Trains will, of course, recall that the Brighton Line was one of the very fast train tracks to be targeted by connectivity suppliers. Way back in 2005, a then-small, Newcastle-based company called Nomad began a pioneering trial system that combined pre-WiMAX protocols to deliver high-bandwidth connectivity to startled commuters.

The spread of on-board WiFi services, trackside wireless delivery and the increasing use of LEO satellites to boost connectivity will all be fully discussed at this year’s WiFi on Trains Conference, hosted by BWCS in London (www.Traincomms.com ).

The Main Sponsors for Traincomms 2026 are Icomera, Huber+Suhner and Nomad Digital. Westermo, Hughes Europe, CGI, Unwired and Eutelsat are also Sponsoring the Conference. Antonics is an Expo Sponsor.

Tickets to attend the Conference are available now via http://traincomms.com/book1.cfm

For more information on attending this year’s Conference please contact [email protected]

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