Lowering the maximum speed limit on the ring road to 80 or even 70 km/hour, the idea caused a lot of ink to flow a few years ago, like that of a second ring road by the east of Toulouse, and she too was eventually discarded. The prefecture had let it be known some time ago. Last week, the publication of a series of studies on projects which aim to decongest Toulouse showed that this decision had been ratified. Above all, this work revealed the reasons for this choice by showing that the reduction in speed on the ring road would have no effect on the fluidity of traffic or on atmospheric pollution.

In June 2018, the prefect of Haute-Garonne announced that a broader reflection was underway on the reduction of the maximum speed on the ring road, a device which, eleven years earlier, in 2007 had gone from 110 km / hour to 90 – who remembers? The idea of ​​a new reduction is then in tune with the times: Lille, Rennes, Paris and others have reported the speed on their city expressways or conducted experiments. 2018 is also the year when the departmental roads go to 80 km / hour in Haute-Garonne and in the other departments. A decision taken a few months earlier by the government and which is not for nothing in the outbreak of the movement of yellow vests.

No effect on traffic

The reduction in the maximum speed is one of the fifteen studies that the State, the Region, the Department, the Metropolis and Tisséo were launched in 2017 to fight against traffic jams in an agglomeration in perpetual growth. The state services, which are responsible for this work, have worked on a drop to 80 or 70 km / hour on the ring road and all the expressways to the airport and to Colomiers, excluding motorways.

Their conclusion is final, can we read in the document that has just been released. “The project does not have a positive effect on the flow of traffic and on traffic conditions during rush hour”. Which is linked to the configuration of the ring road with its close interchanges.

On pollution, the reduction “in pollutant emissions and fuel consumption is limited relative to the 2030 horizon.” In detail, nitrogen oxides are falling slightly, like greenhouse gases, but fine particles grow. “This is explained in particular by the fact that, for heavy goods vehicles, the drop in speed leads to an increase in pollutant emissions”, it is written.

Moreover, this conclusion is also based on an analysis of speed reductions adapted to Rennes, Paris, Lyon, on a motorway between Thionville and Luxembourg, but also in the Netherlands, London and Barcelona. These experiments are, it seems, more or less conclusive on traffic.

In May 2019, Jean-Luc Moudenc took a position “at this stage” against a drop in speed to 80 or 70 km / hour. Driving experiences elsewhere did not seem conclusive to the mayor of Toulouse who had expressed his preference for “the development of the public transport offer and the implementation of new road infrastructures”.