The Dutch safety board has begun an investigation into Monday’s collision between a car and a train on an unmanned level crossing in Friesland which left two people dead.

The driver of the car and his three-year-old son died in the accident when the car was dragged 250 metres down the track before the train stopped.

The crossing is one of some 300 on privately-owned access roads used purely by local traffic. Rail company Prorail has earmarked money to improve safety at unmanned level crossings on public land but no solution has yet been found for private landlords.

The car was in a convoy taking children from the Prins Johan Frisoschool to see newborn lambs on the farm itself.

It is the second accident in six weeks at the crossing, which has red lights but no bells or barriers to warn vehicles of oncoming trains. In February a driver was taken to hospital with injuries after colliding with a train.