Annoyed commuters Tunnel frustration for thousands of SBB customers - what's behind it all

Cell phone reception in the important rail tunnel through the Heitersberg failed for weeks. The reason was a defective fiber optic line.

Anyone who regularly travels by train between Zurich and Aarau has probably already noticed: cell phone reception is not working reliably in the approximately 4.9-kilometre-long Heitersberg Tunnel between Killwangen-Spreitenbach and Mellingen Heitersberg.

In April in particular, there were repeated scenes during commuter times: As soon as the train entered the tunnel, the first "Can you hear me?" calls were reliably heard from travelers in video calls. Hello?" shouts could be heard. Train attendants were also aware of the disruption - but there was initially no official notification from SBB.

SBB only provided information about the cause when blue News asked: "It was a break in a fiber optic cable that supplies the mobile phone providers' tunnel radio system with signals," explained a media spokeswoman. The repair was delayed because access to the tunnel is restricted and the fault could not be repaired until now.

The fault meant that Internet data packets from cell phones took up to two seconds to find their destination. This is too long for video calls and complex web applications: the connection freezes and error messages appear.

Repair delayed

At least: at the request of blue News, SBB apologized to passengers "for the inconvenience caused" and thanked them for their understanding.

And another ray of hope: After intensive planning, a date has now been set. Technicians will be able to enter the tunnel during the night from Thursday to Friday. Mobile phone reception should be working perfectly again from Friday morning.

Anyone who wants to test the reception can visit the Networktest.ch website. It is provided by the Swiss network operators so that customers can test the quality of internet access. The service is required by law.