(Portland, OR)  --  A man is dead, after he was hit by a vehicle while trying to walk across Interstate 5 in Portland.  Police say the man was crossing southbound I-5 near Southwest Hood Avenue around 5:50 yesterday evening when he was hit.  The man, whose name hasn't been released, died at the scene.  The driver remained at the scene and cooperated with police.  Southbound I-5 was closed for several hours.