Madison police said a man drove into a concrete barrier on the bridge over Interstate 90/94 on Monday afternoon.
Madison police responded to a one-car crash in the 5100 block of High Crossing Boulevard at about 3 p.m.
Paramedics administered Narcan, a drug used to revive people who overdose on heroin, and the man regained consciousness, according to a Madison Police Department incident report.
Police said the crash is being investigated as a possible heroin overdose.
The driver appeared to have suffered non-life-threatening injuries, according to the incident report.
Crews were sent to inspect damage on the bridge, according to a Dane County dispatcher.