Study on the Optimization of Design Speeds Required by the Need to Reduce Traffic Pollution

Pollution is closely related to traffic characteristics (vehicle fleet, its composition in terms of motorization, park maintenance level, etc.), existing road infrastructure (depending on the classification of public roads into technical classes, the level of service) and last but not least, the speed of traffic on the public road network (depending on the designed geometric elements, local context, geographical position and climate). Determining optimal traffic speeds in order to reduce pollution is a highly debated topic for all categories of public roads, including highways, which by definition are designed and executed with distinct geometric elements to ensure high-speed road traffic. When adopting the geometric elements, the design speed adopted in accordance with the legislation in force, plays an essential and decisive role both in the design of new roads and in the rehabilitation of existing ones.

The comparative study of the maximum design speeds (imposed by regulations) with the optimal ones in terms of reducing air pollution (recommended by specialized studies), can provide new perspectives from the point of view of all traffic participants by correlating the optimal average speeds with the designed geometric elements.