The day without car in Paris this Sunday offers to the people of the capital a preview of what might look like in their city if there was less car traffic. The mayor Anne Hidalgo, at the origin of this event, has made the fight against the traffic in paris one of its spearheads. In the same vein, she has advocated fiercely for the piétonnisation of the road on the banks right bank. The project, voted on tomorrow, Monday at the council of Paris, is approved by Frédéric Héran, mobility specialist.
You are defending the project of closure of road on the banks of the rive droite in Paris. How do you respond to those who are worried about a thrombosis of traffic?
This is not the first project of the City reducing car traffic. It all started with… the right and Jacques Chirac ! Of course, this mayor (1977-1995) has created a couple of “red axes” to facilitate the flow of traffic, but it also has installed hundreds of thousands of posts to protect the sidewalks from the parking lot wilderness. With Jean Tiberi (1995-2001), tens of kilometres of cycling facilities have been made by deleting of files, entire cars, and it is he who has built the first zones 30 (referred to as “districts alone”). The left was then protected bus lanes with benches, refurbished arteries “axes” civilized”, expanded some of the pavements, increased cycle facilities and the zones 30, turned hubs oversized in public places…
READ more >>Pedestrianization of the road on the banks of Paris: green light for six months to test
All these measures have of course had the effect of limiting the automobile traffic which has been reduced by 28% between 2001 and today. We do not know the decline that preceded it. Yet, the left would be well inspired to remember the reduction for this case is not considered as a partisan issue. Each time, for 30 years, it has not been observed to increase sustainable and insurmountable plugs in Paris. Why would it be suddenly different with the latest instalment of this saga? Many large cities have a downtown that is impossible to cross by car. Paris is behind in this field.
Can you explain the phenomenon of evaporation? On what examples to support your observation? Can we really transpose the case to a capital city like Paris?
every time that it reduces the capacity of the road, there is only a small part of the traffic disappears: about 10% in the short term and a little more-about 20%- in the long term. The “traffic patterns” to identify very well how motorists seek first to find alternative routes in parallel. They have already more difficult to measure how many users are changing their mode of travel. And they fail to identify those who decide to go less far, which organize otherwise their movements, which waive the right to move or end up living or working elsewhere. A move or a job change is rarely the sole pressure of the plugs, but on the occasion of a change in the family’s life or a desire to evolve on a professional level.
This phenomenon of evaporation is observed always and has been measured in dozens of cases around the world, including the centre of large cities such as New York, San Francisco, Seoul, London… We have in France a very pure and perfectly-documented: the closure of the pont Mathilde in Rouen. On 29 October 2012, a tanker truck and pours it into a turn and ignite. Under heat, the bridge structure is distorted and it must be closed. Brutally, 92 000 vehicles per day can no longer use this motorway bridge (43 000 vehicles per day on the voie Georges Pompidou). In seeking to know, with a great wealth of resources, what has become of this traffic, the technicians have never found 10 % of this traffic.
How long will it take before drivers change their behavior? What fraction of them shift to other modes of transport?
It takes a few weeks for users to adapt. It is impossible to be more precise. The trip analysis is not an exact science. We cannot say precisely what will be the modal shift: this depends on the attractiveness of other means of transport. And it is not necessarily to renounce the movement. For example, an artisan may decide to organize better: to move its construction site by starting earlier, better forecasting tools and materials to use to avoid the back-and-forth, or even use a scooter rather than a light truck, etc, The adjustments possible are countless. In fact, these are not the ones who have the most stress that fit, but those who have margins of manoeuvre. And it is through these latter that the former can continue to circulate.
Valérie Pécresse, president of the regional council of Île-de-France, proposes on the contrary to invest in the road to “pop the corks” on the roads of île-de-france. How do you feel?
This type of solution seems to be logical and full of common sense. Everyone, or almost everyone believes that it is enough to invest in highway improvements to reduce traffic congestion. It is an idea very easy to sell to voters. Alas, the reality is more complex. Since the time we invested heavily in the road and as traffic jams persist, it may be necessary to ask yourself a few questions.
When one increases the capacity of the system, it responds not only to the application, but it also encourages people to use the car. Indeed, we observed that the traffic increases by about 10% in the short term and even more long-term, relative to what was provided in the traffic patterns. We speak of the “generated traffic” and this concept is the exact symmetric of the “traffic evaporated’ mentioned above. Again, it is very well populated by a multitude of case studies conducted throughout the world.
in Short, to be clear, the new regional policy will increase car traffic and all the nuisance associated with it, including pollution and greenhouse gas emissions. All the efforts of the parisians will therefore be cancelled, and beyond, through regional policy, electioneering and irresponsible. If you need evidence of what I advance, then I request that this policy be rigorously evaluated, just as will be that of the mayor of Paris at the request of the Prefect of police.