Track-Laying Vehicles Prohibited Post Mount Sign- 622.4 R2/RA2 (Face Only)The regulatory sign with No track laying vehicles should mark where a road can not be used by a vehicle which lays its own tracks. A track laying vehicle is one that turns smaller cogs on its side that roll a length of track along the ground to push it forward with more grip. This can be seen on bulldozers, excavators, military vehicles and agricultural tractors which are damaging or too dangerous for some roads. The sign shares its diagram number