S20 (RER Fribourg)

The S20 is a railway service of RER Fribourg that provides hourly service between Neuchâtel and Fribourg/Freiburg, in the Swiss cantons of Neuchâtel and Freiburg, respectively. The S20 is extended to Romont FR on weekdays. Transports publics Fribourgeois operates the service.

Operations
The S20 runs hourly between Neuchâtel and Fribourg/Freiburg. On weekdays it continues to Romont FR. It uses the western end of the Bern–Neuchâtel line, the entirety of the Fribourg–Ins line, and a portion of the Lausanne–Bern line. It is paired with the S21 between Ins and Romont FR, providing half-hourly service.

History
RER Fribourg introduced the S20 designation on 14 December 2014 for an hourly service between Fribourg/Freiburg and Neuchâtel. In December 2017, the S21, previously a rush-hour service between Fribourg and Kerzers, was re-routed to run between Fribourg and Ins and rescheduled for hourly service on weekdays, increasing the service level between Fribourg and Ins to half-hourly on weekdays. With the December 2021 timetable change, both the S20 and S21 were extended south from Fribourg to Romont, replacing the S40. The S21 began running on weekends with this change, while the S20 operated between Fribourg and Romont on weekdays only.