When you get on the Berlin U-Bahn in the morning, you are often met by a curious sight. The train is full, but it's quiet. People's heads are tilted down, their eyes are on their smartphones.
When the train enters the tunnel, something changes. A few heads go up. Annoyance is written on their faces – the internet is gone. A passenger looks suspiciously at his neighbour. He’s still connected to the internet. How can that be?
Just like above ground, the connection in the underground tunnel often depends on the provider. In most subway systems in Germany, only customers of certain mobile companies enjoy complete 4G coverage.
The fourth generation of 4G (or LTE) mobile phones is currently the most modern data transmission standard.
“We currently have 21 LTE base stations in the Berlin underground,” says Alexander Hausmann. The 51-year-old works as a network planner for special projects for the Spanish operator Telefónica – best known in Germany for its core brand O2. That makes Hausmann responsible for the expansion of the LTE network in the 120-kilometer-long Berlin subway system.
“O2 customers already have full LTE coverage,” says Hausmann. Smartphone owners with Deutsche Telekom or Vodafone though, will have to wait a few more months. By the first quarter of 2019, the entire inner city area is scheduled to be completed for all three mobile network operators. But much still depends on the negotiations with the Berlin Transport Company (BVG).
Unsurprisingly, some parts of Germany are already further developed than the capital.
Of the thirteen cities with an U-Bahn network, four have full LTE coverage. In Hamburg, Munich and Frankfurt, Vodafone have taken responsibility for expanding the network. In Hanover the company also cooperates with Deutsche Telekom. Which operator bears the responsibility usually depends on who started the supply in the city.
It is the passengers' hunger for data that has made underground development a “life's work” for Hausmann. “It never ends,” he says. “As time goes by, there are more and more stations.”
According to O2 figures, data traffic in the Berlin U-Bahn network has increased twelve-fold in the last three years. This means that more than four terabytes of data are sucked through the shafts every day – as much as about 800 films in HD resolution.
While 5G is already on the doorstep, Vodafone spokesman Volker Petendorf says it will not play a major role in the subway system. “You don't really need it to use smartphones,” he says.
And what about Wifi? This has been available free of charge at many Berlin subway stations since 2016. According to BVG, the connection is usually best in the middle of the platform. By the end of the year, the company wants all 173 stations to be equipped with WiFi.
Some people also want it on the trains. “I regret that this has not yet been implemented,” says Oliver Friederici, MEP and transport spokesman. “This is already happening in other cities like Seoul or Moscow. It wouldn't be bad if we had that, too.”
But others don’t consider the expansion of free WiFi to be necessary, as they expect that 4G will become cheaper to use.
“Within the next few years, mobile reception in Germany will continue to improve and prices for large volumes of data will continue to fall,” says Tim Grams, who works in the social media team of Deutsche Bahn.
Hausmann is responsible in Berlin for making this happen. The challenges are manifold: “You only have two to three hours a night,” he says. “The transport to and from the expansion site must also be taken into account. And besides, the BVG work trains also drive through the tunnels at night.”
Work in the capital is complicated by the marshy soil. So-called slotted cables, which are otherwise frequently used in subway systems for radio transmission, would be out of the question here. Instead, Hausmann has to install antennas.
Has it ever become to tricky? Hausmann smiles. “You always find a solution – sometimes it just takes a little longer.”