It happened around 12:30 a.m. on the US-59 exit that connects to the southbound lanes of the 610 West Loop.
The driver told officers that he was taking the ramp when his load shifted, causing him to lose control of the truck, according to Houston police.
Once it went over the barrier, it landed in a muddy area near Westpark Drive. It wasn't clear how far the truck fell, but bridges in the area are at least 14 feet above the road below. The exit ramp from southbound 59 to 610's southbound lanes is approximately 28 feet above the ground at its tallest point.
The trucker suffered minor injuries, police said.