Pierre-Marie-Jérôme Trésaguet (15 January 1716 – 1796) was a French

engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considerin ...

. He is widely credited with establishing the first

scientific approach The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific me ...

to road building about the year 1764. Among his innovations was the use of a base layer of large

stone In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition, and the way in which it is formed. Rocks ...

covered with a thin layer of smaller stone. The advantage of this two-layer configuration was that when rammed or rolled by traffic the stones jammed into one another forming a strong wear resistant surface which offered less obstruction to

traffic Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads) for travel and transportation. Traffic laws govern and regulate traffic, while rules of the road include traffic ...

. Trésaguet was born in

Nevers Nevers ( , ; la, Noviodunum, later ''Nevirnum'' and ''Nebirnum'') is the prefecture of the Nièvre Departments of France, department in the Bourgogne-Franche-Comté Regions of France, region in central France. It was the principal city of the ...

, the youngest son from a family of engineers. He began his career as a sub inspector in the Corps des Ponts et Chaussées (Bridges and Highways Corps), in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...

. He later moved to

Limoges Limoges (, , ; oc, Lemòtges, locally ) is a city and Communes of France, commune, and the prefecture of the Haute-Vienne Departments of France, department in west-central France. It was the administrative capital of the former Limousin region ...

Haute-Vienne Haute-Vienne (; oc, Nauta Vinhana, ; English: Upper Vienne) is a department in the Nouvelle-Aquitaine region in southwest-central France. Named after the Vienne River, it is one of the twelve departments that together constitute Nouvelle-Aquitai ...

as chief engineer in 1764. In 1775 he was appointed inspector general of roads and bridges for all of France. He published a paper describing his road building methods.

Method of road building

First of all an earth foundation was excavated parallel with but about ten inches below the finished surface of the new road. This was

convex Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytop ...

in cross section to encourage water to drain off the finished surface. Next, large stones were laid on edge and any protruding pieces on their upper edges broken off to leave an even surface. This stone foundation was covered with a second course of smaller rounded stones. Finally a third layer of hard broken stone, (about the size of walnuts) was spread by a shovel to produce the surface layer. This system was used continuously in France from 1775 until 1820 when the country changed to the cheaper

Macadam Macadam is a type of road construction, pioneered by Scottish engineer John Loudon McAdam around 1820, in which crushed stone is placed in shallow, convex layers and compacted thoroughly. A binding layer of stone dust (crushed stone from the ...

method.

References

*Arthur G. Bruce, ''Highway Design and Construction'', International Textbook Company,

Scranton, Pennsylvania Scranton is a city in the Commonwealth of Pennsylvania, United States, and the county seat of Lackawanna County. With a population of 76,328 as of the 2020 U.S. census, Scranton is the largest city in Northeastern Pennsylvania, the Wyoming V ...

(1934) 1716 births 1796 deaths People from Nevers 18th-century French engineers 18th-century French people French civil engineers Transport pioneers {{france-engineer-stub

Method of road building

See also

References