Michele turns hard to the left after crossing the bridge and seeing Madison's ghost and ends up in the river. She was coming from her house as she crossed the bridge and if you remember when Harrison Ford gives his address during the fake 911 call he said that it was a mile away from the bridge. When michelle comes up from the water you see a police car on the bridge coming from behind her. The police car was coming from the wrong direction... her house... he should have been crossing the bridge away from the scene and not towards it.