Cars are bad. More cars mean more accidents, pollution, climate change and congestion. Less cars are the way to go, whatever it takes. Or so the story goes. In 1999 Chantal Duchène, a green elected official, then Director of transports at the Ile the France Regional Directorate of the Equipment stated: “It will be necessary (…) to reduce the space available for the automobile. With lanes reserved for buses, bike paths and widening of sidewalks, car travel times will lengthen and other modes will become more interesting” (Journal du Dimanche, September 5). Following policies have been coherent with this statement. The length of the reserved lanes for buses doubled and that of cycles paths is now five times what it was in 2000, going from 292 to 1.442 km.
Since 2003 to 2022, the average speed of vehicles decreased from 16.4 to 12.4 km/h while traffic has been halved. In terms of mobility by car this is obviously a bad result, and is what you can expect by withholding some of the supply and creating an artificial scarcity. In fact, the efficient policy to deal with excessive congestion (some congestion is desirable) is to lower the demand with road pricing.
Let’s consider the situation in terms of externalities.
Safety first: in Paris, there were 54 people killed in road accidents in 2003 and 38 in 2022. A large improvement, no doubt. The trend is even better for France as a whole (see Figure 1), especially if one considers that road traffic in France, unlike what happened in Paris, increased by 9%.
Figure 1:
It is a fifty-year-long trend. 1972 was the worst year for road safety. Since then, road traffic almost tripled, mortality rate fell by 92% and the number of people killed decreased by 80% (Figure 2).
Figure 2:
The main factors explaining this progress are the improvement of vehicle technology, better roads, stricter and more strongly enforced traffic rules. Instead, it is at least doubtful that promoting a shift from cars to bicycles can have a positive impact on safety.
A 2012 analysis referring to the Dutch situation assessed the effect on safety if ten percent of all car trips shorter than 7.5 km were replaced by bicycles. The result is a (small) net increase in the number of fatalities.
A similar argument can be made for air pollution.
In Paris, as in all the other western cities, air quality has been improving since half of the past century. The main pollutant today are particles with a diameter of less than 2.5 micrometres (also known as PM2.5). Measurements of this pollutant started around the ‘90s.
Historically, fines particles were measured using the “black smoke” method. This measurement takes into account the black (carbonaceous) particles with diameter less than 5 micrometres.
The average concentration of this pollutant has been reduced twenty times since the ‘50s.
The average concentration of the NO2, the second main pollutant, decreased by around 40% from the 90’s. The major reason for the improvement is linked to the renewal of the road fleet. The emissions of a Euro6 car are about 95% lower than those of a Euro0 vehicle.
It has also been showed that a specific project, the closure of the Voie Georges Pompidou, an expressway crossing downtown Paris, led to an increase of NO2 concentration because of the displacement of some commuters to the ring road and to the nearby central streets.
What about CO2 and climate change? Are bikes really better than cars? Bikes are indeed (quasi) carbon free, but a shift from cars to cycling is both ineffective and inefficient. It is ineffective because only a small share of a nation’s car traffic can be replaced. In 2019, the Dutch made 3 km of cycling per day per person while the average distance travelled by car was 25 km (Figure 3).
Figure 3:
Moreover, for every litre of gasoline not used, 2.35 kg of CO2 are avoided. But, at the same time, treasuries (in Europe) lose around 70 cents or 300€ per ton of CO2 with which they could finance a much larger reduction in other sectors (for example the present price of emissions allowances in the EU Emissions Trading Scheme is 70€).
To sum up: policies devoted to lower traffic have today only a rather limited effect on air quality and safety and tomorrow it will be even lower than today. Which kind of cars are on the road is much more relevant than their number. The only realistic way to lower CO2 emissions is, again, technology.
One may argue that with fewer cars on the streets the quality of life in Paris has improved. But that is not probably true for people who have chosen a different mode of transport or place to live after the worsening of traffic conditions.
Of course, mobility is not the only factor on which people choose their residence, but it is not irrelevant. In a 2005 article French economist Rémy Prud’Homme wrote about the “temptation of Venice” for Paris. Venice as a model of city without cars and where trips are very difficult. A beautiful city where population and employment were – and still are – rapidly decreasing in favor of the mainland.
If we look at the demographic figures, we discover that from 2011 Paris lost 150 thousand inhabitants while the rest of the Ile de France gained 500.000 residents. In other words, the unintended consequence of a car free city may paradoxically be more people and more cars just outside its borders.
