Contractor BSB Staalbouw said on Thursday it made mistakes during preparations for the failed attempt to lift a bridge part into place in Alphen aan den Rijn.

The accident happened on August 3 during extensive renovation of the Juliana bridge.

Two cranes standing on pontoons in the river which were lifting part of the new bridge into position toppled over, destroying or damaging around 50 properties. No one was hurt.

BSB Staalbouw director Jan Pesie told Dutch media the plan to lift the bridge part should have been shown to a specialist company.

‘We do not have the expertise ourselves to work out the stability and ballast requirements for putting the cranes on pontoons,’ he said. ‘I failed there. I must do better in the future.’

Since the accident, Alphen aan den Rijn council has said it is holding BSB Staalbouw and a second contractor, Mourik, liable for the damage.

Alphen mayor Liesbeth Spies said last week it could take weeks before the cranes and the bridge section are removed and months before the rubble is cleared.

In the meantime, people evacuated from their homes have been found temporary housing.