The Platte County Sheriff's Department says the 30-year-old man fell from the I-435 overpass onto the shoulder of southbound I-29 in Platte County.
The man's name has not been released.
He was taken to the hospital with severe injuries.
Deputies say the man's truck was found running on I-435.
The sheriff's department says it's unknown at this time of the fall was accidental or intentional.