The helicopter was flying to the west, into the sun, at 250 feet above ground level. The pilot heard a loud "bang" and observed a black object go by the left side of his helicopter. The passenger side windshield was struck by the object. The pilot performed a forced landing to the highway. During the forced landing, both landing skids separated and the helicopter slid to a stop. The lower fuselage was buckled and wrinkled in several locations. The pilot reported no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.