The reach and control of the Roman Empire relied on an ever-expanding system of roads . The Roman road building engineers left nothing to chance. Based on usage and location , the roads were assigned a level of importance – which in turn determined the construction details . They were designated as public , military, local and private .
There are many common elements used across the roadbuilding spectrum . A crown ( high point in road middle ) , ditch , foundation built with various aggregate sizes and very thick stones – some placed long axis down – were all basic formulae . The most important roads had a very deep foundation (1 – 1.5 Metres ) with a multi-layered aggregate complex of diminishing size. In addition to the usual crown and ditching, curbing was an additional refinement . By building on a platform the water drainage improved and the Roman Army gained a better view of the area . In traversing wet ground , the entire road was elevated above the high water mark .
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