Regional planning and resource management of aggregates – AGREGA

The supply of natural aggregates in France will become an important issue over the coming decades due to the expected increase in market consumption. This is true for the building sector (inter alia due to the “Grand Paris” project and its 70,000 housing units/year by 2030) as well as for public works (inter alia due to the construction of 4,500 km of new high speed rail lines by 2030). However, faced with this expected growth, estimates made by the aggregates profession, in terms of production, seem alarmist since they announce a supply shortage. This is due to the existence of at least the following constraints: de facto constraints (urbanization, etc.), environmental constraints (decrease in alluvial production) and societal constraints (low acceptance of production activities near to residential areas due to the noise generated).

In light of this increasingly critical situation, the French aggregates profession, in association with governmental and regional authorities, has invested in a policy aimed at meeting the following challenges: (1) intensifying recycling and assessing the eventuality where existing norms may evolve to make feasible the incorporation of recycled materials into concretes (which is not currently permitted), while also assessing the limits of this initiative (control of use, extra cost of the handling, etc.), (2) in order to meet the market needs not covered by the above recycling intensification process, increasing the use of natural aggregates with a low environmental impact; and (3) continuing the work aimed at making the activity as acceptable as possible to politicians and local residents.

The successful implementation of the above policy requires a suitable planning tool. However, existing tools, often GIS-based, only provide decision makers with a static view of the situation, whereas management policies of the aggregates market are determined in the long term. Simulation-based tools are in this case more efficient, especially with regard to spatial decision making. The present project aims to carry out the methodological and operational implementation of this type of tool for the aggregates sector at a regional scale. The regional scale was chosen because of the current progressive transition in France from departmental quarry schemes to regional quarry schemes.

The AGREGA project aims to develop a methodology and an operational simulation tool for prospective analysis of the aggregates market at the regional scale over a 30 year period. The tool aims to guide and visualize, in a spatial-temporal manner, the combination of the actions of recycling intensification (and its limitations) and that of gradual closing of alluvial quarries. The result will consist in an assessment of the prospective evolution of the market variables with integrated economic (costs, etc.), environmental (recycled quantities, etc.), geographical (location of future primary and secondary productions areas, constraint areas, etc.), geological (available substance volume, etc.) and social (activity acceptance) dimensions.

The prospective simulation will be based on the multi-agent system (MAS) approach in order to represent the heterogeneity of French regions. Regarding the socio-economic analysis related to the acceptability issues, the MAS simulation will be integrated in a more global assessment based on a modelling and participatory approach, called INTEGRAAL, which aims to engage experts and stakeholders in the dialogue and decision making process.

The work will firstly be applied to the Ile-de-France region and all the surrounding regions that supply it (because it is structurally deficient and must therefore import a high proportion of its consumption). The choice of Ile-de-France is also due (1) to the “Grand Paris” project (2) to the potential of marine aggregates, transportable via the river Seine, and (3) to the current status of this region as the second largest producer of recycled aggregates in France.