The document discusses highway construction methods for road bases. It describes that road bases are constructed from durable aggregates or hot mix asphalt to distribute loads and provide drainage and frost resistance under the road surface. Aggregates used must be crushed rock, free of impurities, and meet impact value and shape requirements. Bases can be single sized or multiple course, with thicker bases using larger aggregates. Proper preparation and compaction of base materials in multiple lifts is needed to support traffic loads on the road surface. Quality control testing monitors aggregate properties and construction specifications.