The bike park underneath Utrecht’s Jaarbeurs exhibition centre has been closed after cracks were found in the main construction.

“Further research is needed to find out the cause,” the city council said in a statement. “We have decided to close the bike park to guarantee the safety of users and to carry out the research carefully.”

Part of the bike park was already out of action because of water damage.

As yet, it is unclear how long the bike park, which has space for some 4,000 two-wheelers, will remain closed and the city has set up a temporary parking area above ground.

Bikes that are still in the bike park cannot be picked up and officials say they don’t know when this will be possible, leading frustrated commuters to wonder how they will complete their journeys.

“I live in Rotterdam and I have no idea when I will get my bike back. It is ridiculous,” one angry student told local broadcaster RTV Utrecht.

The problems do not affect the nearby bike park under Utrecht’s main railway station, which has space for over 12,000 bikes, making it the biggest underground garage for bikes in the world.