Among the 14 killed were drivers of the ten-wheel truck and the passenger truck.
Police said the ten wheel truck was returning to Bangkok after having delivered zinc sheets to customers in Mae Sot district of Tak province before noon Wednesday.
As the ten wheel truck was making a curve near Kilometer marker 67/400 on the Tak-Mae Sot highway, it developed braking failure. The truck lost control, hit a pickup truck running on the same direction, and collided head-on with an oncoming passenger truck.
Fourteen people died and two others were injured, many of them were hill tribe people.
All the injured and bodies of the victims were sent to Taksin Maharaj hospital.
The crash scene was 500 meters off the scene where a double-deck bus crashed and plunged into a ravine on the same highway killing 31 people last month.