Pedestrian overpass. The site appears to have been, in better times, a recreation facility. Note the four tennis courts just north of the bridge? The area immediately east of the bridge appears to be either a college campus or perhaps a military barracks and the bridge was likely built to connect the tennis court area to some never-completed facilities south of the road.
This map has changed quite a bit since its posting in 2005. The bomb craters have been filled in and a base has sprung up in their place. The bomb craters in the nearby maps "Baghdad Bomb Craters" I & II have also been filled in.