Evaluation of traffic polluting gases emissions using OR techniques: the case of the city of Tunis

The purpose of this paper is to show how the operations research techniques can help to evaluate the emissions of polluting gases from road traffic in urban area. Our practical study case is the center of
Tunis city.
To evaluate the emissions of several polluting gases (CO, CO2, SO2, NOx, CH4 and VOC), we have combined the traffic assignment model ATESAME [1] with new module implementing the CORINAIR [2] formulas.
The traffic assignment model corresponds to a static User Equilibrium model that can be computed by solving a nonlinear optimization problem (See Sheffi [5]). This nonlinear convex model can be efficiently solved by using the classical Frank Wolfe technique. The CORINAIR formulas give an expression of the unitary emissions, i.e. the emissions per kilometer, as a function of the vehicle speed and of the current temperature.
Several scenarios of traffic congestion and emperature conditions have been simulated for the center of Tunis City. We present here the mains results from the simulations for the center of Tunis city.