On 21 April 2012 at 18:30 local time (16:30 UTC), two trains were involved in a head-on collision at Westerpark, near Sloterdijk, in the west of Amsterdam, Netherlands.

While initial reports varied, 117 people were injured, 13 critically, 43 or 44 seriously, and dozens more had minor injuries.

[4] The VIRM unit received moderate damage, with deformation at the rear of the first and front of the second carriage.

[2][3] By Sunday afternoon, traffic was partially restored with a full service expected by that evening.

[14] A reporter from de Volkskrant travelled on board the SLT train, immediately behind the cab.

The director of Nederlandse Spoorwegen, Bert Meerstadt, said it was still too early to guess the actual cause of the incident and it was necessary to await the conclusions of the investigation.

[7] The Dutch Safety Board (DSB, in Dutch: Onderzoeksraad Voor Veiligheid, OVV) conducted one of the investigations,[15] whilst the other was being conducted by the Human Environment and Transport Inspectorate (Inspectie Leefomgeving en Transport, ILT).

[17] De Telegraaf reports that the driver may not face prosecution however as a report submitted by ProRail, the operator of the line, to the ILT, showed the signal in question was part of an older system and it is guessed that if it had been one of the more modern signals, fitted with upgraded safety equipment, the train would have stopped in time.

In particular, they investigated why the trains collided, and why the accident caused over 100 injuries and one fatality considering the marginal speed at the crash site.

The driver fairly expected a stopping signal, but she could have been distracted by a freight train passing nearby.

Shortly after passing the signal at danger the safety system allowed the local train to accelerate to 60 km/h (37 mph).

Three minutes is the minimum time interval for passages over single track sections allowed by regulation.

After the collision, people were catapulted through the train and hit objects such as panels, seats and tables, causing severe injuries, and a single fatality.