NS said it plans to double the service frequency between Alphen aan den Rijn and Gouda from September.
Four trains an hour will run in both directions from September 4. This higher frequency service will operate until 7pm on weekdays.
NS said the extended timetable had been developed in collaboration with the province of South Holland, ProRail and the municipalities of Alphen aan den Rijn, Waddinxveen and Gouda.
NS has operated R-net services on the route since December 2016. Upgrades made to the signalling and track infrastructure by ProRail have created the additional capacity to run the extra services.
Two new stations are also due to open on the line as part of an ongoing investment programme for the route. A new station in Boskoop Snijdelwijk is due to open in December this year followed by Waddinxveen Triangel in spring 2018.