Le Figaro Nantes
"This Tuesday, it took me an hour and a half to get to the office. As often, it jammed on the ring road": this testimony of Paul, resident of the town of Cellier, collected by Le Figaro is not original. Driving on the road that surrounds the city of Nantes is often a challenge. Bison Futé's map used to turn red - or even black - on the 42 kilometers of this infrastructure contained on two times two lanes on the vast majority of its route.
On the ring road - covered by an average of 110,000 vehicles per day - traffic continues to increase, reflecting the demographic dynamism of the sixth largest city in France and its economic development. It is still necessary that the traffic jams do not slow it down too much. This is why a steering committee (Copil) that brings together several actors - prefecture, Nantes Métropole, Department and Region - is responsible for defining development projects. It met Tuesday morning to take stock of those in progress and present those to come. Overview.
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Bellevue Interchange: a three-lane bridge
The Cheviré bridge is not the only one to cause traffic jams for several kilometers on the Nantes ring road. In the eastern part of the route, the Bellevue Bridge has a rather bad reputation with motorists. The prefecture describes it as a "node of congestion" crossed by an average of 90,000 vehicles per day. As early as 2010, studies were launched to try to solve the problem. Several scenarios were submitted at the end of 2021 to a public consultation that was "a great success" according to the services of the State with "350 observations filed".
The main evolution of the solution chosen by the client - the Regional Directorate for the Environment, Planning and Housing (Dreal) - consists in the creation of a third lane to cross the Loire. Other improvements are planned: the installation of a two-lane ramp between the A811 and the inner ring road, an intersecting lane between the Carquefou and Sainte-Luce gates, a third traffic lane between the Sainte-Luce and Vignoble gates and a two-lane entrance to the RN249 (road linking Nantes and Cholet) to the outer ring road. "The cost is 117 million euros," say the authorities. A budget that could increase by another twenty million euros.
The reason: the Copil plans to propose "complementary developments", in particular in favor of "active mobility" (pedestrian-bike), and to create a lane reserved for public transport (VRTC) upstream and downstream of the one already planned at the Bellevue bridge. Before all this happens, motorists will have to continue to be patient. "Public inquiries are expected to be launched in 2025-2026. The start of work is scheduled from 2028," it is anticipated.
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Cheviré Bridge: a lane reserved for public transport
Another "bottleneck" frequently saturated of the ring road, the sector of the bridge of Cheviré, which culminates at 52 meters in height, will be reviewed in order to "promote public transport". Thus, south of this area (between the gates of Bouguenais and Grand-Lieu), in both directions of traffic, the emergency lane will be transformed at "rush hour" into VRTC to accommodate coaches and buses to play the role of "back line". Specific markings will be visible and the speed will be reduced to 50 km/h. This project must be the subject of prior consultation next October. The start of work is expected for the year 2025 with commissioning towards the end of 2026.
Noise pollution on the decline
In 2022, a new acoustic campaign - after those of 2001, 2007 and 2014 - was conducted by the Observatoire du bruit du périphérique nantais. "If at night, the averages remain equivalent (53 decibels, Editor's note), there is a significant decrease in nuisance during the day," notes the Departmental Directorate of Territories and the Sea. The average is now 56 decibels compared to 60 decibels eight years ago. According to French regulations, noise from the Nantes ring road is considered "moderate".
This device is similar to the one launched last August in the sector linking the A83 to the Nantes ring road, whose initial feedback is positive. On average, those who use the buses save six minutes on this section compared to other users. "Subscribers to the lines of the Aléop network now have almost the assurance of knowing what time they arrive whereas before there could be a differential of 30 minutes," says Julien Bainvel, regional councillor (LR) in charge of mobility in Loire-Atlantique. A phenomenon that would have attracted new passengers, forcing the Region to develop the bus offer.
Another development planned in the Cheviré Bridge sector is the creation of several intersecting lanes that extend an insertion ramp to the exit ramp of the next interchange. North of the bridge, four will be developed - two in each direction of traffic - between the gates of the Estuary, Saint-Herblain and Atlantis. They are expected to be commissioned in 2025. South of the bridge, an intersecting lane will be created in the interior direction between the gates of Retz, Grand-Lieu and Bouguenais. Its commissioning is scheduled for the end of 2026.
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A83: a lane reserved for carpooling
The experiment, which is due to begin next September for one year, is presented as "unique in France". If other cities in France have already set up lanes reserved for carpooling - like Lyon - the subtlety of Nantes lies in the fact that this development, named "VR2+", will be carried out on a two-lane section. This is the one where the A83 joins the Nantes ring road. Who will be able to circulate there? Public transport, which is already allowed with the new HRV, as well as all vehicles with at least two people on board. Important precision: the speed will be reduced to 50 km / h against 70 km / h today.
"The goal is to avoid autosolism [being alone in your vehicle, editor's note] and promote carpooling. This should allow more users an estimated time saving of four or five minutes," explains Arnaud Gauthier, deputy director of the Interdepartmental Directorate of Western Roads (Diro). To ensure compliance with this new rule, "an automated control system" to know the number of passengers on board will be implemented, warns Pascal Otheguy, secretary general of the prefecture of Loire-Atlantique. For the time being, its form remains unknown. "It will not be a portico," assures the Figaro Arnaud Gauthier, without saying more on the subject.
If the experiment is successful, the VR2+ device could extend to the south of the agglomeration on a frequently "congested" axis, according to Freddy Hervochon, vice-president of the Loire-Atlantique Department in charge of mobility, namely that of the RD178 to the Viais interchange, located in the municipality of Pont-Saint-Martin. This evolution is anticipated for the end of 2027 or the beginning of 2028. The implementation of a carpooling lane on the road to Pornic (RD723) is also planned during the year 2027.
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Porte de Gesvres: the construction site is "on schedule"
The vast road project carried out at the Porte de Gesvres, which connects the Nantes ring road to the A11 motorway - an axis that connects Paris to Nantes - on which Le Figaro visited last January, is "on time" according to Eric Bon, the site manager for Vinci Autoroutes, the main financier of the road project (75%) with local authorities (25%). A new exceptional operation is also scheduled for the night of June 13 to 14. The framework of the east viaduct - 106 meters long and weighing 750 tons - will be positioned in one piece on the supports of this extraordinary structure using large self-propelled modular trailers.
"The first effects of the construction site on traffic will be visible this summer," predicts Eric Bon, who cites the sector of the Pont de la Chapelle and that of the tracks of the northern ring road. Traffic will be opened "with a limited speed" because of the work in progress. The release of the entire redevelopment project is scheduled for the first quarter of 2024.