The current 1.5kV railway traction power supply system is reaching its limits in the Netherlands and therefore, ProRail is investigating the replacement of this system by the 3kV railway traction power supply system. This study will investigate how effective the 3kV traction power supply system can increase the capacity of the rail infrastructure in the Netherlands. It will also investigate if this system can avoid other capacity investments in the infrastructure. Several study cases will be executed in order to evaluate the capacity effects of the 3kV traction power supply system.