Hellfire Pass in the Tenasserim Hills was a particularly difficult section of the line to build : it was the largest rock cutting on the railway , it was in a remote area .
The workers lacked proper construction tools during building .
Hellfire Pass in the Tenasserim Hills was a particularly difficult section of the line to build : it was the largest rock cutting on the railway , it was in a remote area and the workers lacked proper construction tools during building .