50 Hz track circuits parallel to a 25 kV 50 Hz railway line

In the port of Rotterdam a new freight line, the so-called ‘Havenspoorlijn’, is built partly alongside an existing DC subway line (‘Erasmuslijn’). This freight line will be equipped with a 25 kV 50 Hz power supply. The signalling system of the subway uses 50 Hz track circuits for train detection.