Houston Transtar cameras captured the flames ripping through the rig along the southbound lanes of I-45 North, just south of West Road, around 11:30 p.m. Tuesday.
The driver escaped the torched rig.
All southbound lanes were closed in the area at one point. Seven hours after the fire, all lanes are back open.
"We were driving down I-45 and heard a boom, boom, boom," said witness Jonathan Johnson.
Johnson told ABC13 he pulled in to a nearby hotel parking lot to see if anyone needed to be rescued.
"'Oh my God, is anybody in there, do I need to help? What do I need to go do?' But I found that nobody was in there," Johnson said.
It is not known what caused the fire or what the 18-wheeler was hauling at the time.
This incident comes less than 24 hours after three 18-wheelers were involved in accidents on different, major Houston roadways.
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