Seattle police say a driver was crossing the bridge, but was going too fast when using the off-ramp to Michigan Street. Investigators say that's when she lost control, and plunged over a concrete barrier, falling 25 feet onto South River Street below.
The black Honda Accord was left a mangled mess at the 100 block of South River Street, near the Duwamish River.
Police taped off the area and shut down South River Street for several hours while investigating the scene.
The woman was rushed to Harborview with life-threatening head injuries.
No one else was in the car, and no other vehicles were involved.