According to police, a pickup truck was eastbound on the South Loop feeder around 11pm when the driver swerved off the road for unknown reasons.
A witness told investigators it almost looked like the driver thought he was taking an entrance ramp to enter onto the freeway.
The truck drove into the trees between the freeway and feeder road, plowing down several small trees and hitting the guard rail at the top.
Authorities said the truck flipped and the driver was pinned inside. Firefighters had to cut him out of the vehicle and he was transported to Memorial Hermann Hospital. At last check, he was stable.
Police believe he may have been highly intoxicated. A blood test was performed at the hospital.