While on an orientation flight with the CO, this FAC was pointing out the border areas between Laos and North-Vietnam. Recent Presidential decree ceased the use of strikes in that section of NVM.  While looking at a mountainous area of the border, it became clear that a new road was being built from NVM to Laos.  A little more orbiting found a large bulldozer working on a new section of the road.  The bulldozer was clearly inside of Laotian territory, but still too close to the border to work air on it.  Now, it must be remembered that all FACs who flew the trail salivated at the sight of any bulldozer; knocking off one in hilly or swampy terrain areas generally created a choke point where supplies would pile up for several days thus enabling future strikes in the area to be more productive.  So, here was a rather large bulldozer, very visible, in a mountainous terrain area, making it a very tempting target.  A quick check with the CO and it was decided because of the proximity to the NVM border and the mountainous terrain, the couldn't put air on that piece of equipment.  It was also obvious that the Dozer driver had been eyeballing the FAC but did not seek cover or stop working on the road.  The decision was made "NO AIR"; the FAC looked over the area again and turned away from the target.  Then, after briefly wrestling with the situation, the FAC abruptly turned the OSCAR-DEUCE around and fired a WP at the bulldozer.  The Dozer driver, still eyeballing the FAC, bailed out of the bulldozer as the rocket was fired.  Both pilots watched the Dozer driver run for cover and the bulldozer continue to run.  The WP impacted close to the road, but missed the bulldozer.  However, they watched as the bulldozer continued its driverless run and left the road, rolled over a steep embankment, and crashed into the deep ravine below.  Neither the FAC nor the CO made eye contact or commented on the course of events.  A large bulldozer would be denied the road crews for awhile, thanks to one resourceful FAC.