The 10,000-hour airline transport pilot of a twin-engine tandem pusher-type experimental airplane collided with electrical power lines while attempting a landing on a highway. The pilot, sole occupant of the airplane, became concerned that items in his un-zipped flight bag, which was located in the airplane's rear seat, might blow out of the cockpit "and be sucked into the propellers" while on a local flight. The pilot stated that since there was not any vehicular traffic on the highway, he elected to make a precautionary landing on the highway to correct the problem; however, he failed to note that power lines were crossing the highway. The airplane collided with the power lines while on final approach to his intended point on the highway. After the collision with the powerlines, the pilot continued the approach and landing without incident. The collision with the power lines resulted in structural damage to the airframe. The pilot reported, that at the time of the accident, the weather was clear of clouds with the visibility in excess of 30 miles.