Increase of road traffic is closely related to a region’s economic prosperity. Increased economic activity stimulates transport demand for individuals, goods and freight, which puts pressure on the road network. However, the problems of traffic jams have become a serious social issue throughout the world. It is simply impossible to accommodate all vehicular traffic demand through the construction of new roads. Moreover, the construction and improvement of roads themselves invite further economic development, leading to more vehicles on the network, which may exceed the added capacity and worsen the situation. Increased numbers of vehicles also have negative side effects other than congestion. Therefore, network operations have to include ways to manage and control traffic on the network, rather than forever playing catch-up with traffic demand.
The policy challenge is to determine whether to intervene with control measures and how best to achieve the desired results. Local policy objectives vary from achieving the maximum unimpeded traffic flow without compromise, to one of severe traffic calming with priority to pedestrians, cyclists, animal transport and other classes of slow-moving traffic. However, intervention is more widely used to help achieve policy objectives.