A main road linking the capital with the southern region was cleared for traffic on Sunday after it was submerged by floodwater on Saturday.
The Highway Department declared Highway 41 in Thung Tako district of Chumphon safe for all vehicles and reopened the road after the high water level blocked traffic on Saturday.
Land transport between the central and southern regions was blocked on Saturday due to floods in the district.
The State Railway of Thailand on Sunday also resumed southern services after the track in Sawi district of Chumphon was inundated on Saturday.
Repairmen worked through the night to make repairs and reinstall the traffic signal system before giving the green light for stranded trains to move on.
Train passengers could not continue their trips by bus because of the floods on Highway 41 that prevented the railway agency from dispatching buses to take them to their destinations.
Bangkok-bound trains were ordered to stop at Tha Chana station in Surat Thani and Lang Suan station in Chumphon, while southern-bound trains were parked at Chumphon and Sa Phli stations in Chumphon.
Flash floods began to hit Chumphon on Friday and Sawi district was one of the hardest-hit areas.
The Meteorological Department on Sunday warned of heavy rain and flash floods in nine southern provinces, including Chumphon, until Monday.