I think electrification of each rail line will be needed before doubling of conventional lines. For example, North Main Line of the State Railway already has more than 80km of double tracks extended from Bangkok. So, doubling won't be necessary for the time being.
But, there is no electrified section on the lines of State Railway of Thailand, which prevents the railway company from increasing train service. In this situation, electrification should precede doubling tracks or construction of 250 km/h standard gauge lines.
And, what made me wonder is that one of 250 km/h standard gauge lines would be extended to Malaysia, though conventional line which had connected Thailand and Malaysia was disconnected at Sungai Kolok.
Anyway, improvement of conventional lines should precede constructing new tracks.
