Traffic Mitigation Programs

Traffic Restriction

Traffic restriction measures limit traffic in some parts of the road network. The limitation can be permanent or temporary (valid only at specific times of the year, week, or day) and can apply to all or some vehicles, depending on their characteristics (for example, size, age, contribution to the emission of air pollutants, or license plate number).

One example of traffic restriction is the limitation of traffic in all roads and streets within a specific area of the city. This policy is known as areawide traffic restriction and is often applied in the city center, with examples found throughout Europe. The restriction may apply to private vehicles only or to all motorized traffic. However, in most programs, the restricted links are open to local residents and, at some times of the day, to freight vehicles.

These measures are introduced as a means to reduce traffic levels and congestion in areas with high concentrations of travel destinations for work, study, or shopping trips, and where the road capacity is insufficient to meet the demand for road space. The policy also promotes the mobility of pedestrians, as the limitation of road traffic is usually applied in conjunction with the “pedestrianization” of some streets.

The reduction of traffic has benefits in terms of reduced accident risk, air pollution, and noise in the areas of application. The introduction can then be justified in terms of social equity, because, in many cities, the central areas are inhabited by populations particularly vulnerable to deteriorations in pedestrian mobility and environmental quality, including the elderly, low-income populations, and racial minority communities.

Road space rationing is another example of traffic restriction policies. In this case, the restrictions are based on vehicle license plate numbers and apply on certain days of the week only. The measure has been used in Athens, Greece, several Latin American cities (such as Mexico City; São Paulo, Brazil; and Santiago, Chile), and more recently in Beijing, China. The restriction usually applies to road links where congestion is particularly high, such as the main commuting corridors from suburbs to major centers of employment.

Empirical studies show that the application of road space rationing leads not only to the reduction of congestion in the restricted links but also to reductions in the emission of air pollutants at the city scale. By restricting the possibility or reducing the convenience of car trips, the policy may also contribute to a modal shift to public transit or non-motorized modes.

...