Impact of speed control traffic signals on pollutant emissions

The paper uses experimental measurements to explain the interaction between the signal control settings and emissions and traffic variables. The data for validation were gathered on Highway N6, connecting the cities of Lisbon and Cascais, in Portugal. Emissions are computed based on a modal approach. Trade-offs between level of enforcement against added emissions are explored. One of the main conclusions of the research is that signal control schemes that result in stopping a larger fraction of speed violators also yield higher emissions. On the other hand, if the speed control traffic signals modify drivers' behaviour by inducing speed reduction, they will also result in a decrease in relative pollutant emissions.