Pierre-Marie-Jérôme Trésaguet
Encyclopedia
Pierre-Marie-Jérôme Trésaguet (1716, Nevers
– 1796) was a French
engineer
. He is widely credited with establishing the first scientific approach
to road building about the year 1764. Among his innovations was the use of a base layer of large stone
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
.
Trésaguet was 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
. He later moved to Limoges
, Haute-Vienne
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.
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
method.
Nevers
Nevers is a commune in – and the administrative capital of – the Nièvre department in the Bourgogne region in central France...
– 1796) was a French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
. He is widely credited with establishing the first scientific approach
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering empirical and measurable evidence subject to specific principles of...
to road building about the year 1764. Among his innovations was the use of a base layer of large stone
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
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
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...
.
Trésaguet was 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
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
. He later moved to Limoges
Limoges
Limoges |Limousin]] dialect of Occitan) is a city and commune, the capital of the Haute-Vienne department and the administrative capital of the Limousin région in west-central France....
, Haute-Vienne
Haute-Vienne
Haute-Vienne is a French department named after the Vienne River. It is one of three departments that together constitute the French region of Limousin.The chief and largest city is Limoges...
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 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
Macadam is a type of road construction pioneered by the Scotsman John Loudon McAdam in around 1820. The method simplified what had been considered state-of-the-art at that point...
method.