Nederlandse Spoorwegen (Dutch Railways), or NS, is the principal passenger railway operating company in the Netherlands. Its trains operate over the tracks of the Dutch national rail infrastructure company ProRail, which was split off from NS in 2003.

The Dutch railway system is said to be the most crowded network in Europe. In fact, the Dutch railway system is said to be the 3rd most crowded network in the world. The NS therefore announced that all railway traffic will be rerouted in a more efficient way starting in December 2006 to prevent the network from becoming dangerously overcrowded and to increase punctuality.