Read the linked article!
https://www.thaipbsworld.com/is-the-massive-land-bridge-project-worth-the-trillion-baht-investment/
There will be two deep-sea ports, in Ranong and Chumphon, with cargo terminals and oil depots to receive oil from tankers from the Andaman Sea. The oil will be pumped through a pipeline to depots in Chumphon, on the other coast, for shipment to destinations beyond Thailand.