The accident happened just before 11am, as the driver went on the ramp from the Gulf Freeway to the South Loop. Police say the 18-wheeler was going too fast on the I-45 ramp when the truck slammed into the retaining wall, rolled and crashed down to the highway below.
Eyewitness Victor Gallegos said, "I saw a truck going over the bridge."
Gallegos, who was driving home alongside Gulf Freeway, says he is still in shock by what happened next.
"I saw the truck collapse," he said.
That 73,000 pound 18-wheeler and its 40-year-old driver went rolling and then crashing onto the I-610 ramp below. With the truck driver on his mind, Gallegos pulled over and ran to the mangled big rig, where he found the driver conscious.
"He was looking for the phone and I was like don't worry about the phone," Gallegos said. "It could be anywhere because the truck, it was actually like in two pieces. So I said there is no way you are going to find it."
The 18-wheeler had been ripped into pieces.
Houston Police Officer Francis DeVita said, "You've got the engine hit so hard it twisted out of its mount. You've got the transmission sitting in one spot the engine sitting in another."
With smoke coming from the wreckage, Gallegos was desperate to help pull the driver out of the truck. That's when the good Samaritan discovered what he and others are calling a miracle. The driver's only injury was a single scrape
"I told him to go to a safe zone and sit over there," Gallegos said. "He was bleeding from the elbow." Officer DeVita said, "Thankfully he was wearing a seatbelt because the only injury we saw was a scrapped elbow."
Gallegos says now he has a picture to remind him of what happened and he hopes one day he can share them with the truck driver.
"He thanked me. I said yeah, no problem," Gallegos said. "I'll keep in touch with him."
Crews worked for hours to clean up the truck's load of plywood and the wreckage of the truck.
The truck driver was treated at the hospital for minor injuries. No one else was hurt, as no other vehicles were on the road below.
The truck is owned by Houston company Gulf Winds International. They told Eyewitness News, "We are blessed the driver is in great condition."
The 40-year-old driver has been with the company for about two years, we're told, and this is his first accident. Police say he will be ticketed for failure to control speed.