On our way to Tequila, a semi lost its trailer. It careened across the road in front of us and clobbered another truck on the other side. If we had been 5 seconds further along it would have wiped us ...
Rarely happens on a highway. If the 5th wheel did not lock the trailer will usually drop at the first turn. But being this is Mexico one does not know if the 5 th wheel or the king pin was 40 years old and metal fatigued. They would never think of checking these items!