The Nakhon Ratchasima Highway Office announced on Thursday that it would open three checkpoints on Motorway No 6 that runs from Bang Pa-in district in Ayutthaya to Kham Thale So district in Nakhon Ratchasima (Korat) on April 11, in time for Songkran, when more motorists are expected to use the highway to travel to their hometowns in the Northeast.