Impact of the Madrid M-40 ring road on emission from road traffic

Madrid is a city with a high population density and 4.6 million inhabitants. The structure of the city and its location at the hub of the Spanish road network means it has high traffic densities which have a negative effect on the environment. The atmospheric pollution is particularly serious as a result of the difficulty of dispersing the pollutants owing to long periods of atmospheric stability, inversion, etc. One strategy to improve the situation has been to build orbital motorways to reduce the traffic pressure in the most densely populated central zones and to stop heavy traffic passing through the center. In view of the opposition of certain collectives to the completion of the northern section of the M-40 Ring Road, an environmental impact study was made on the distribution of global emissions with and without its construction. After designing models for the traffic behaviour under the two scenarios for 1995, traffic speed and density loads were obtained for each stretch of the network. Based on the results, pollutant emission was determined for each zone involved. The results show that the new infrastructure will improve traffic conditions, providing significant reductions in journey times and will also reduce the global emission of pollutants in the short term.