The infrastructure ministry’s roads department closed a busy tunnel on the A4 motorway for a time on Monday morning because no one was available to monitor traffic.

The Kethel tunnel near Schiedam was shut because the operator who monitors traffic flows had called in sick, as did his replacement, the ministry said.

‘If there is no one to keep an eye on what is happening, or to close the tunnel if there is an accident, then we have to shut it anyway,’ a spokesman told NOS radio.

Motorists travelling between The Hague and Rotterdam were diverted via the A13 and A20 motorways.

The tunnel was reopened shortly before 9am, motoring organisation ANWB reported.