Editing Macadam (section)

===Pierre-Marie-Jérôme Trésaguet===
[[Pierre-Marie-Jérôme Trésaguet]] is sometimes considered the first person to bring post-Roman science to [[road]] building. A Frenchman from an engineering family, he worked paving roads in Paris from 1757 to 1764. As chief engineer of road construction of [[Limoges]], he had opportunity to develop a better and cheaper method of road construction. In 1775, Tresaguet became engineer-general and presented his answer for road improvement in France, which soon became standard practice there.<ref name=LayVance>{{citation |year=1992 |author=Lay, Maxwell G |title= Ways of the World: A History of the World's Roads and of the Vehicles That Used Them |place=New Brunswick, N.J. |publisher=Rutgers University Press |page= 73 |isbn=0-8135-1758-3 |url=https://books.google.com/books?id=flvS-nJga8QC&q=Tresaguet&pg=PA73 |access-date=18 June 2010}} Paperback {{ISBN|0-8135-2691-4}}</ref>

Trésaguet had recommended a roadway consisting of three layers of stones laid on a crowned [[subgrade]] with side ditches for drainage. The first two layers consisted of angular hand-broken [[Construction aggregate|aggregate]], maximum size {{convert|3|in|cm|1}}, to a depth of about {{convert|8|in|cm|0}}. The third layer was about {{convert|2|in|cm|0}} thick with a maximum aggregate size of {{convert|1|in|cm}}.<ref name="Lay1992p73">Lay (1992), p.73</ref> This top-level surface permitted a smoother shape and protected the larger stones in the road structure from iron wheels and horse hooves. To keep the running surface level with the countryside, this road was put in a trench, which created drainage problems. These problems were addressed by changes that included digging deep side ditches, making the surface as solid as possible, and constructing the road with a difference in elevation (height) between the two edges, that difference being referred to interchangeably as the road's [[Cant (road/rail)|camber]] or [[cross slope]].<ref name="Lay1992p73"/>