If you're coming from Papendrecht or Alblasserdam, buses stop at the Sliedrecht Baanhoek station. From there, you can easily transfer to the train to Dordrecht

Trains on the MerwedeLingelijn run between Gorinchem and Dordrecht Monday through Saturday every 15
minutes from 6:40 a.m. to 8:00 p.m., including during school vacations.

On weekdays, extra buses run four times an hour between Dordrecht Stadspolders Station, Leerpark, Gezondheidspark, and Dordtse Kil II and III. In the evening, there are extra trips for hospital staff.

With a special Qbuzz subscription, you can continue to travel at the regular rate. Discount offers are available for new passengers via the link.