Dimensioning practices structures of roadways in France

The theoretical methods of dimensioning are not accessible to all the originators who they are State or territorial collectivities. This is why of the standard catalogs of structures was elaborate in order to make it possible to choose very simply and in manner practices the structure of a roadway according to the supported traffic, of the type of way and the platform support. The catalog in force in France east that of 1998

History

The French method of pavement design was developed in the Sixties for the rebuilding of the network damaged by the exceptional winter of 1962-1963. The first catalog of the structures of semi-emprique roadways, semi-calculated was established in 1971. A new completely calculated version was produced in 1977.

The last version of the catalog of the structure-types of roadways goes back to 1998. The step employed is identical to that of the catalog of 1977 but comprises two additional stages:

determination of the category of the way,
the choice of the composition of the surfacing.

It will be noted that the determination of the category of the way always refers to the circular of December 9th, 1991 defining a typology of the roads in urban environment. However since 2004, decentralization and the transfer to the departments of the two-thirds of linear of trunk roads contributed to change this categorization notably. But there was reactualization of the terminology no yet.

Practical method

The catalog is appeared as a set of cards of definite structures starting from the category of the way, of the cumulated traffic which will have to support the roadway and of the platform support of roadway.

The synoptic one of the step followed by the originator is the following:

Determination of the category of the way

For the pavement design, one will differentiate two highway types:

ways of the structuring network (VRS) corresponding to types 1 and 2 of the typology of the roads in urban environment (highways and expressways),
ways of the network not structuring corresponding to types 3 and 4 of the typology of the roads in urban environment (interurban arteries and other roads),

Determination of the class of traffic

In the cards of structures, the data of traffic taken into account is a class of cumulated traffic.

See also: Class of road traffic in France

It is then advisable to distribute the traffic heavy trucks by lane and to calculate the number cumulated of heavy trucks on the way charged.

Determination of the platform support of roadway

Choice of the structure of roadway

The preceding parameters having been defined, it is enough to choose one or more structures starting from the cards to structures.

Choice of the surfacing

All the cards of structure, excluded those of the roadways concrete, reveal a surfacing, noted CS. This surfacing includes/understands a layer of roulemnt and possibly one even two binder courses. For the majority of the cards of structures, several combinations of surfacings are possible.

Checking with freezing-thawing

The checking with freezing consists in comparing:

the Frost index atmospheric of reference, noted IR, which characterizes the rigor of the winter opposite from which one wishes to protect the roadway,
with the Frost index acceptable of the roadway, noted IA, This index is evaluated according to the structure of roadway, the sensitivity to freezing and the frost-resistant thickness of its support.

associated Articles:

Gelivity

Transverse section of the roadway

See also: Establishment of a transverse section of roadway in France

associated Articles:

Competition of structures different thicknesses

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