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Less cars in central Paris, more pollution on the outskirts

Léa Bou Sleiman
Léa Bou Sleiman
Léa Bou Sleiman is a doctoral student in urban and environmental economics at the Centre de Recherche en Économie et Statistique (CREST) at École Polytechnique (IP Paris)
Key takeaways
  • Urban congestion causes problems, particularly air pollution, which according to the WHO is responsible for 4.2 million premature deaths per year worldwide.
  • In 2016, the City of Paris closed the “voie Georges-Pompidou” - also known as the “les voies sur Berges” - a road covering 3.3km and used by around 40,000 vehicles per day.
  • As a result of this policy, pollution shifted location resulting in an increase in NOconcentration in the air around the Eastern ring road to 70μg/mwhile in the centre, the pollution rate remains around 40μg/m3.
  • To curb this pollution and these problems, the reopening of the road at certain intervals (during rush hours for examples) or the introduction of an urban toll are possible solutions.

Traf­fic con­ges­tion in urban areas is noth­ing new. The city of Paris, known for its traf­fic jams, tried to improve urban flow by increas­ing the num­ber of lanes in the 1980s. But this attempt led to what is known as the Bræss para­dox. That is, adding or mod­i­fy­ing roads (and thus the num­ber of lanes) mod­i­fies the flow of traf­fic to the point that it actu­al­ly reduces over­all effi­cien­cy instead of reduc­ing con­ges­tion. In addi­tion, the prob­lem of con­ges­tion is also close­ly linked to the issue of pol­lu­tion, in par­tic­u­lar air pol­lu­tion. Accord­ing to the WHO, air pol­lu­tion is respon­si­ble for 4.2 mil­lion pre­ma­ture deaths per year world­wide1, caused in par­tic­u­lar by expo­sure to (ultra)fine par­ti­cles in cities. In response to this grow­ing pub­lic health cri­sis, sev­er­al lane clo­sure poli­cies have been intro­duced, although they are reg­u­lar­ly chal­lenged due to the lack of evi­dence regard­ing their sup­posed effect on air quality.

Greener centres, greyer suburbs

In 2016, the City of Paris closed a cen­tral road that runs along the riv­er, known as the “voie Georges-Pom­pi­dou” or “les voies sur Berges”. Used by around 40,000 vehi­cles per day over a dis­tance of 3.3 km, this stretch of road pro­vid­ed access to Paris and cer­tain sub­urbs for com­muters. While the clo­sure of this thor­ough­fare has had a num­ber of ben­e­fi­cial effects with­in the city – such as air qual­i­ty, need for more pub­lic space, and reduc­tion in noise pol­lu­tion – com­muters have tend­ed to divert jour­neys to oth­er routes rather than take pub­lic trans­port. As a result, the west to east-bound lanes of the south­ern ring road (“périphérique-sud”) have seen their con­ges­tion increase by 15%, adding two min­utes on aver­age to commuter’s car jour­neys over a dis­tance of 10km. 

The prob­lem of con­ges­tion has there­fore just been moved from the banks of the Seine to the sub­urbs, where cit­i­zens are already expe­ri­enc­ing an over­all increase in res­pi­ra­to­ry com­pli­ca­tions among their res­i­dents. Accord­ing to a study con­duct­ed by the Air­parif asso­ci­a­tion2, 5,040 pre­ma­ture deaths in the Greater Paris region and near­ly 7,920 in Ile-de-France were record­ed between 2017 and 2019. There is no indi­ca­tion that this increase is a direct result of the increase in con­ges­tion in the city, but it is cer­tain­ly not improv­ing the situation. 

Air pol­lu­tion has there­fore shift­ed, increas­ing the NO2 con­cen­tra­tion in the air to 70μg/m3 around the east­ern ring road (“périphérique-est”) in 2015. Where­as, in the cen­tre, the pol­lu­tion rate remains around 40μg/m3. This indi­cates that areas which were already heav­i­ly affect­ed by pol­lu­tion prob­lems are becom­ing even more so and that the impact on health, although dif­fi­cult to quan­ti­fy, could be sig­nif­i­cant in years to come. 

Map of Paris show­ing expo­sure to pol­lu­tion3

Our analy­sis of the sub­ject4 seems to indi­cate that the rea­son why dri­vers do not change their mode of trans­port is because they are unable to do so. As the growth of pub­lic trans­port has not kept up with demand, pub­lic poli­cies penalise “trapped dri­vers” liv­ing in the sub­urbs who con­tin­ue to use their car due to the lack of alter­na­tives. It is there­fore cru­cial to inte­grate alter­na­tives into future mea­sures in order to have pos­i­tive long-term effects on the whole region and to avoid a per­pet­u­al shift in road congestion.

What are the alternatives?

Oth­er solu­tions have been con­sid­ered abroad. Some cities, such as Lon­don and Seoul, have intro­duced con­ges­tion charges, the cost of which is cal­cu­lat­ed accord­ing to the aver­age impact of a vehi­cle in terms of con­ges­tion (i.e. “con­ges­tion charge” in Lon­don). How­ev­er, it is dif­fi­cult to apply such a fee in France, where polit­i­cal ten­sions around envi­ron­men­tal tax­es are very high. The increase in the car­bon tax in 2018, which was final­ly can­celled fol­low­ing the “Gilets jaunes” move­ment, is one of the most bla­tant exam­ples of the oppo­si­tion by the peo­ple of France to this type of tax­a­tion. More­over, it would serve to increase social inequal­i­ties because in France, unlike in oth­er coun­tries such as the Unit­ed States, the least well-off part of the pop­u­la­tion lives in the suburbs. 

There are a num­ber of ideas which could be imple­ment­ed to reduce con­ges­tion on the roads with­out aggra­vat­ing exist­ing social divi­sions, in par­tic­u­lar the idea of clos­ing and open­ing the river­banks at dif­fer­ent times of the day. In order to do this, it is nec­es­sary to con­sid­er how to opti­mise the use of the river­banks in rela­tion to the ameni­ties they pro­vide. Because, when the lanes are closed, they are used for eco­nom­ic pur­pos­es. For exam­ple, it could be ben­e­fi­cial to close off the Berges to traf­fic out­side of rush hour on week­days (8am-6pm) to ease traf­fic for com­muters work­ing in the cap­i­tal and at the same time allow for the use of ameni­ties which are not nec­es­sar­i­ly required dur­ing peak hours. 

How­ev­er, these solu­tions all entail dif­fer­ent costs, par­tic­u­lar­ly for open­ing and clos­ing the banks, which would require staff. The right solu­tions are com­plex and need to be care­ful­ly con­sid­ered so that all sides can find a solu­tion that ben­e­fits them. 

Interview by Fabien Roches
1https://​our​worldin​da​ta​.org/​d​a​t​a​-​r​e​v​i​e​w​-​a​i​r​-​p​o​l​l​u​t​i​o​n​-​d​eaths
2https://www.airparif.asso.fr/actualite/2022/avec-les-recommandations-de-loms‑7–900-deces-pourraient-etre-evites-en-idf
3 https://​www​.ipp​.eu/​p​u​b​l​i​c​a​t​i​o​n​/​m​a​i​-​2​0​2​1​-​d​e​s​-​c​e​n​t​r​e​s​-​p​l​u​s​-​v​e​r​t​s​-​d​e​s​-​b​a​n​l​i​e​u​e​s​-​p​l​u​s​-​g​r​ises/
4Léa Bou Sleiman, 2021. Are car-free cen­ters detri­men­tal to the periph­ery? Evi­dence from the pedes­tri­an­iza­tion of the Parisian river­bankWork­ing Papers 2021-03, Cen­ter for Research in Eco­nom­ics and Sta­tis­tics.

Contributors

Léa Bou Sleiman

Léa Bou Sleiman

Léa Bou Sleiman is a doctoral student in urban and environmental economics at the Centre de Recherche en Économie et Statistique (CREST) at École Polytechnique (IP Paris)

Léa Bou Sleiman is a PhD student in urban and environmental economics at the Centre de Recherche en Économie et Statistique (CREST) at École Polytechnique, under the supervision of Benoît Schmutz and Patricia Crifo. His work focuses on public policies related to cities, with a particular emphasis on environmental and transport aspects. The main objective of his research is to study the central role of transport in today's cities, to estimate the optimal road capacity in cities and to assess how transport influences individual travel behaviour, both theoretically and empirically.