Norwegian State Railways (NSB) promises that staffing levels will be at required levels for the summer, but personnel shortages have already made their impact felt before the usually complicated holiday season.

Michael Tung of the Train Drivers Union in Oslo and NSB information chief Preben Colstrup confirm that a lack of drivers is the problem.

Tung said that there is a general shortage of drivers and the ones working have been putting in long hours this spring. Once staff start taking summer holidays, these drivers know that periods of overtime and long shift will occur, and so they are not overdoing it now.

"Working extra shifts week after week makes people tired and sad. They know that they will be getting a lot to do again in a few weeks," Tung said. Tung didn't rule out that the fine spell of weather might have helped convince drivers to say no to overtime shifts now.

Additional factors for the shortage are private companies, such as the airport shuttle, and a generally open and active job market, that have tempted away drivers for the state railway.

Tung said that NSB is aware that there are not enough drivers to cover all routes, but instead of canceling trains in advance and announcing these stoppages, they try to tempt drivers to take on extra shifts and cancel when they fail to cover gaps.

"If we didn't do it this way there would be more cancelled trains. It is very regrettable, and I understand public frustration. But I want to say that our people are really working hard," Tung said.