ExtensionSaint-Germain > Achères
Forest offsets related to protected species
The project was designed by integrating the avoid-reduce-compensate approach within the meaning of the Environmental Code. First of all, it is a question of avoiding impacts as much as possible: limitation of rights-of-way by reusing the Grande Ceinture, implementation of markings during the construction phase, etc.
If the impacts cannot be avoided, it is then a question of reducing them: creation of large wildlife passages in the forest, adapted lighting, differentiated habitat management plan, installation of roosts for avifauna, etc.
Finally, when the impacts could not be avoided or reduced, they must be compensated: Île-de-France Mobilités has defined a compensation programme for protected species ticket, which consists of the recreation of environments favourable to the protected species impacted by the project.
The compensation process for all the impacts of the project on protected species (birds, hedgehogs, bats, etc.) is carried out by Île-de-France Mobilités. It is mainly spread over four sites:
- the Île de Devant in Conflans-Sainte-Honorine, on 17.77 ha, which is a complementary and distinct project from the project of the City of Conflans-Ste-Honorine;
- the "Lisière Saint-Jean" in Achères in the immediate vicinity of the "Forêt domaniale de St-Germain-en-Laye" on 2.28 ha;
- the "Bois des Alluets" in Orgeval, on 22.28 ha;
- a 3.7-hectare section of the Grande Ceinture in the commune of Poissy, which no longer belongs to the national rail network following a procedure completed in 2024 for the decommissioning and closure of the line.
Complementary accompanying measure
Île-de-France Mobilités will also finance the implementation of senescence islands in the Saint-Germain forest, which will be implemented by the ONF. An island of senescence is a part of the forest that is removed from silvicultural exploitation: the trees develop, age and end up falling naturally, thus creating favourable environments for fauna and flora.