Yes, P'lok is half way down, so N Sawan will be 60%, but Bkk to P'lok is only 50%. More complicated than British Rail.. Leaves at 08.50 arriving 14.30. All sorted, thanks.
Driving Bkk to P'lok isn't too bad, only about 4 hours as most of it is 120. But P'lok to Ch Mai is a PITA but a lovely view most of the way.