“We are running two trains every 10 minutes between Odenplan and Alvik. But the transports are working – and that is a relief,” said Jesper Petersson at local transport operator SL.

Starting at 4.11am Thursday morning, problems arose with the electrical systems serving the green and blue metro lines in the Swedish capital, leaving many routes at a complete standstill.

The malfunction halted traffic between Alvik and Odenplan on the green line, as well as between Kungsträdgården and Västra Skogen on the blue line.

Replacement buses were deployed, but most of the 100,000 commuters affected by the outage were forced to find alternate routes to work.

“It is never possible with such a major disruption to replace all metro departures with buses. One bus takes around 100 passengers, ten buses are needed to replace a full train. So there are a large number of morning travellers who are affected,” Pettersson said on Thursday morning.

Some transit hubs became so crowded during the morning rush hour that SL was forced to call in security guards to ensure commuters didn’t fall down on the tracks, according to the Dagens Nyheter (DN) newspaper.

A problem was traced to a switchboard in Kristineberg and technicians were finally able to solve the problem shortly before 12pm.

“It is from there that the power is transmitted along the tracks and it is there that something has gone wrong,” Pettersson said.

Delays along the green line are expected to continue the rest of the day, according to SL’s website. And while trains continue to function on other parts of the Stockholm metro, trains normally serving those sections have also been delayed due to the green and blue line malfunctions.

On Wednesday the Stockholm metro’s red line was also halted due to a power failure.