Trains between The Hague and Rotterdam will run every five minutes from 2025 to meet rising commuter demand.
The government is spending €300 million on upgrading the line and stations between the two cities to allow eight intercity trains and six sprinters to make the journey in both directions every hour.
The biggest change is between Rijswijk-Zuid and Delft, where the number of lines will be increased from two to four. The change has been made possible by the completion of the new Delft tunnel.
The upgrade is part of the High Frequency Rail Travel Programme (PHS) which is designed to increase capacity on the busiest lines. Since December last year trains have run every 10 minutes between Amsterdam, Utrecht and Eindhoven.