At the University of Barcelona we have analyzed the impact on air pollution of thevariable speed policies – limits change depending on the road and weather conditions – and maximum limitation at 80 km / hon the access roads to the city of Barcelona. The result is that although the variable speed policy achievesreduce pollutants such as PM₁₀ (suspended particles less than 10 microns)and nitrogen oxides (NOₓ), limiting the maximum speed from 120 or 100 km / h to 80 km / h has no effect or is even counterproductive. The research, published inTransportation Research Part D: Transport and Environment, concludes that homogenization in the flow of traffic, avoiding stops and starts, would play an important role in reducing pollution.
An extension of the research work in the same journal analyzes the effect of the two options according to the degree of contamination. The days of maximum pollution,the measurement of the variable speed manages to reduce NO contaminación pollution by 9.4%; while for PM₁₀ this reduction is 5.1%. On the contrary, activating the speed limit at 80 km / h would have no effect on pollutants when the pollution is maximum. On days when the pollution is average or well below, the variable speed manages to reduce the pollution of both pollutants, while 80 km / h still has no effect.
Finally, a general consideration. During these years of economic crisis, the lower number of trips in private transport has hidden pollution problems from us; the rebound in economic activity is already implying a greatertraffic and congestion in big cities. Thus, it must be taken into account that the variable speed policy, although effective, ends up having only a limited impact when it comes to solving the problem of air pollution.
Jordi Rosell, researcher at the Institute of Applied Economics Research (IREA), Faculty of Economics and Business of the University of Barcelona. This article has been written in collaboration with the Communication Unit of the University of Barcelona.
