The pilot was landing at a private airport that is used to support fish cannery operations. A road runs parallel to the runway with multiple intersections where motor vehicles cross the runway. The airport is equipped with a pre-landing alert system to warn ground personnel that an aircraft is approaching. The pilot keys the aircraft radios push to talk switch multiple times, which activates a series of flashing lights and horns. The pilot reported that before landing he activated the pre-landing alert system, and proceeded to land to the North. After touchdown, but during the landing rollout, at approximately 30 miles per hour, a truck entered the runway and struck the left side of the airplane. The airplane sustained substantial damage to the left horizontal stabilizer and elevator. The pilot stated that there were no preaccident mechanical anomalies with the airplane that would have precluded normal operation. In the recommendation section of the NTSB Accident/Incident Reporting Form 6120.1, the pilot stated that the accident may have been avoided if the cannery provided initial and recurrent training for all employees on runway safety and aircraft operations. In addition, the pilot recommended better signage be incorporated at all runway intersection crossings, and brush and trees be cleared from the vicinity of the runway thereby increasing visibility.