SPIJKENISSE (AFP).- Cranes safely lifted a Dutch metro carriage off a huge sculpture of a whale's tail on Tuesday, a day after the artwork stopped the runaway train from crashing to the ground.

The train smashed through buffers at the end of the line at Spijkenisse near Rotterdam early on Monday and was left suspended 10 metres above the ground, propped up only by the huge silver monument.

In a painstaking, dawn-to-dusk operation, emergency services cut the 22-tonne front carriage from the rest of the train on Tuesday before two enormous yellow cranes lifted it to the ground.

"It took some more time than we actually wanted to," Carly Gorter, spokesperson for the Rotterdam-Rijnmond safety region, told AFP at the scene.

"It is because we couldn't really see what was under there (the carriage) and we found some things that we didn't calculate so that was a safety risk."

Some superficial damage could be seen on the 20-year-old sculpture, which stands in a local park and is coincidentally named "Saved by the Whale's Tail".

The driver of the train was unhurt in the incident and there were no passengers on board at the time.

Gorter said the cause of the crash remains "really unclear" but that Dutch authorities were hoping that the train's "black box" data recorder, located in the front carriage, would provide more clues.

© Agence France-Presse