A bit earlier, the LBJ Express Twitter feed alerted its followers to a "pedestrian incident" on 635.
Pedestrian incident on 635 WB @ Dallas North Tollway.Three lanes shut down.Expect major delays.
— LBJ Express Project (@lbjexpress) January 14, 2013
The details are still sketchy, but WFAA is reporting that witnesses saw a man pulled his car to the side of the Tollway, get out, and jump from the overpass onto LBJ.
According to the Morning News, the man's body remained in the westbound lanes as police investigated. Traffic is reportedly backed up to Central Expressway.
Update at 4 p.m.: According to DPD, the man was taken to Parkland in unknown condition. He was not struck by any vehicles and has not yet been identified.