Cancelled in Crawley? At least your train has free Wi-Fi now, right?

Why your connection is as slow as the service itself

Cargo train coupling photo via Shutterstock

Wi-Fi has been creeping its way on to UK trains over the last few years as the government seeks to deal with the issue of mobile dead-zones by getting the train companies to provide free connectivity.

However, very low caps and aggressively throttling can make what is an often already unpleasant train journey all the more frustrating

The project kicked off in December 2016, when the Department for Transport (DfT) agreed with Thameslink, Southern and Great Northern (aka the Triumvirate of Fail, as far as recent experience goes) to amend their franchises to provide train Wi-Fi.

The DfT lobbed the train companies some cash to fit the equipment and also pay for data in the hope that while the actual services wouldn't improve, passengers would at least be able to distract themselves with memes before being ejected from an abruptly cancelled train at Haywards Heath.

The DfT set a limit on the data allowance that it deemed sufficient for browsing and email purposes, and reckoned that 50MB would be more than sufficient. With much of the rail network staggering along on an infrastructure designed for the 19th century and earlier, capping based on web page sizes from the last century seems eminently sensible.

As of today, the median desktop page consumes 1709.4KB while it appears on your browser, and so-called mobile pages take 1565.8KB. It won't take long to burn through that 50MB.

And gosh, if you fail to tell Windows 10 you're on a metered connection and forget to limit what Store Apps and Windows features can do in the background, that 50MB could be gone in minutes.

The DfT then left it to the train operators to decide what should happen once that allowance has been burned through, and throttling is the name of the game. Passengers on Southern trains will see their bandwidth drop to a 1990s level of 0.5Mbps. Clearly, the roaming rules occasionally used by some mobile operators also apply to trains.

Demonstrating a misunderstanding of how load balancing works, a representative of Govia Thameslink Railway (GTR) told The Register that the 50MB limit was actually in place to ensure each user gets a fair amount of "bandwidth".

The technicals

While GTR may struggle a bit with how it all works, Icomera, which fits the gear, is more than happy to spill the beans. The Faraday-cage effect of a train carriage does not work well for devices inside, such as mobile phones (often leading to conversations punctuated with an occasional swear and "I'm on the train. The train!"), so Icomera sprays the top of the train with antennas. Adding 4G SIM cards from a variety of operators means the system should be relatively immune from the mobile not-spots that plague commuter lines.

Up until the train plunges into a tunnel built in the age of steam, of course.

Sweden-based Icomera told El Reg that train operators, such as Swedish Rail, were able to offer far more data due to keener pricing by the mobile operators. A commercial chat is needed between mobile operators, the DfT and the UK rail operators to see similar levels of service arriving in Blighty.

Icomera was also keen to jump on the 5G bandwagon, pointing out that it was also developing tech that would allow train companies to upgrade to the next generation of connectivity without having to refit an entire carriage. With 5G capable of shovelling prodigious amounts of data over the air, that 50MB limit should last, oh, a fraction of second.

Passengers excited by the prospect should keep in mind that things move slowly in the railway world. The venerable Class 421 trains were ferrying passengers around the Southern region some 40 years after they were introduced, while Northern passengers still get to enjoy the delights of 30-year-old trains that were converted from Leyland buses in the form of the unloved Pacer.

Even 5G won't take that long to move from vapour to reality. Right? Right?

For the time being, 50MB remains the limit (and Icomera reckon no more than 25 per cent of users hit it). Once throttling kicks in, passengers will be able to enjoy an internet experience that is as slow as the train on which they are stranded.

Hurrah for progress. ®




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