As the train accelerated away from Sassemheim station between Leiden and Schiphol, the coupling between the final intermediate vehicle and the driving trailer at the rear of the train failed, severing the brake pipes and bringing both sections to a halt.

The train has been taken to NedTrain's depot in Haarlem for inspection and NS has withdrawn all 11 sets available at the time of the incident as a precaution. The Dutch Environmental and Transport Inspectorate (ILT) has also launched an inquiry into the split.

The NID sets are being rebuilt from DD-AR regional trains for intercity use in a €235m programme involving 190 coaches and 50 power cars. The first completed train was unveiled in February and the refurbishment programme, which is being carried out by NedTrain, is now in full swing.