The convergence of tracks between Stockholm Södra and Central Stations were upgraded by worried workers last summer, who told a local radio channel about their worries that the kilometre-long convergence area had become a security risk. Ulf Olofsson, professor at the Royal Institute of Technology, backed up their assessment.
"If you have to secure the tracks in over 500 places on a one kilometre stretch, that says you have lost control over the tracks," Olofsson told Sveriges Radio (SR).
At 6.30am Tuesday, a cargo train derailed. It left a commuter train full of passengers stranded in the tunnel and the big station closed off by security personnel. As well as putting a stop to capital region commuter traffic, long-haul passenger rail was affected.
While the cargo train was not loaded, a toxic or otherwise potentiall harmful cargo could have spelled disaster at the station. On Wednesday, as some traffic had picked up on the stretch, observers took turns analysing the cause of the accident.
"Either there's something wrong with the infrastructure," said Seko union negotiatior Jörgen Lundström."Or something has gone wrong with the engine or wagons. As we are behind schedule on maintenance, not least on this stretch of rail, it would not suprise me if it was due to infrastructure."
The accident came as litte surprise to opposition MP Anders Ygeman, who sits on the parliamentary committee on traffic.
"If you can move the rails with just one hand, it isn't difficult to see that a several-tonne train can move it. This is the stretch of rail with the most traffic in the country," he told the TT news agency. "Which means it should be the best maintained, but clearly it isn't."
Infrastructure Minister Catharina Elmsäter-Svärd agreed, said the government had assigned more funds to maintenance, but said a crucial problem in Wednesday accident was that engineers were awaiting the completion of the new Citybanan commuter rail line before a complete overhaul.
Despite the heavy traffic and congestion risk on the tracks, Elmsäter-Svärd said she believed there was a low risk of accidents in central Stockholm.
Public transit operator SL has warned commuters that it will likely take at least a week to repair track following the accident, meaning several days of reduced commuter rail service in Stockholm.