The area does not require to be closed to the traffic. The movement of traffic will improve the compaction of the surface. In fact, no additional compaction is required after the unpaved surface has been treated. This is not uncommon in the case of untreated surfaces, as the fines are easily removed by wind and by the moving vehicles. Preferably, there should be no material larger than 1 in.
Material primarily composed of sand also needs to be avoided.
Ditches filled with gravel and vegetation would impede the water flow during rain, which could flood the road surface. The road surface thus flooded with water, with time, could wash away the fines in the roadbed, rendering it unstable. For better drainage of water, it is also important that road surface is graded, leaving a Crown in the center of the road. The ditches need to be pulled during pre-application process to gather lost aggregates and to allow the free flow of the drained rain water. Yes, as it will reduce the dust level.