We were driving south from Phetchaburi today during a rainstorm. Some 15k before Cha-Am The traffic slowed down. Except the 10 wheeler in front of our car. Suddenly it's brakeligths lit, it slipped sideways and hit the concrete mid wall. After that it crashed other truck, that was stopped. I managed to steer away from them and switched on my hazards.
The whole road was on standstill in front of us. Basic Thai congestion. Cars were only changing lanes. No forward movement. Some smart*sses made u-turns and headed back north on left roadshoulder. Then came BiB, who picked random cars, and led them through along the shoulder. We luckily among them.
Finally we saw the reason for this mayhem. There was a two line wide slab of tin roof lying on the road. I guess the storm has ripped it off from one of the roadside buildings.