They wanted to go fast. Faster than a car at rush hour on the Rennes ring road (Ille-et-Vilaine). The technicians of the Interdepartmental Directorate of Western Roads will finally have to temporize. Engaged in a study to reduce congestion on the Rennes ring road, the DIRO had proposed the creation of intersecting lanes. Already used in Nantes or in a scale model near Roazhon Park, this device creates a third lane solely dedicated to vehicles entering or leaving the ring road. Two are planned in Rennes but it will be necessary to go through a more in-depth impact study than what had been envisaged. Explanations.
The news was announced in November 2021, two months after the publication of a disputed ranking which made Rennes the most congested city in France. Two intersecting lanes were going to be created to improve traffic flow on the ring road. One 1,300 meters long would connect the Porte de Saint-Brieuc to the Porte de Saint-Malo, the other would link the Portes de Bréquigny and Nantes outside. Installed in place of the hard shoulder, these lanes do not require colossal work and the DIRO hoped to launch the first project at the end of 2022 for commissioning at the start of 2023. This was without counting on the Ministry of Ecological Transition, which called for an environmental assessment.
The appeal filed by the DIRO to oppose it was rejected by the Environmental Authority, which maintained its request for an impact study this summer. “It does not call into question the project but it postpones the start of work by a little more than six months, probably in the fall of 2023”, explains Alain Carmouët, head of the maintenance and modernization department of the DIRO network.
The environmental investigation will oblige the DIRO to go through a public inquiry, which will lead to the opinion of an investigating commissioner. The impact on biodiversity and wetlands will have to be studied. But what the Environmental Authority fears is that these new lanes will attract even more vehicles, generating noise and air pollution. “We don’t want to attract more vehicles, just make the entrances and exits on the ring road more fluid. In Nantes, it works well. Especially since by limiting congestion, we also reduce pollution and noise,” assures Alain Carmouët.
The construction of the first intersection lane planned in Beauregard was estimated at 3.4 million euros in 2021, but the bill should increase due to the surge in certain materials. As for the project planned in Bréquigny, shorter but more complex, it is estimated at 2.3 million. It could be held on the same schedule.