Road space rationing

This article is about regulatory and non-monetary policies to reduce traffic levels from motorized vehicles. For monetary policies to reduce congestion and other externalities, see road pricing.
Not to be confused with road diet.
Road space requirements for 30 people in 20 cars (left) compared to 30 people on bicycles (middle) and 30 people in a single bus (right)
Traffic congestion persists despite São Paulo's municipal no-drive days based on license numbers, implemented since 1997. São Paulo downtown, Brazil.

Road space rationing, also known as alternate-day travel, driving restriction and no-drive days (Spanish: restricción vehicular; Portuguese: rodízio veicular; French: circulation alternée), is a travel demand management strategy aimed to reduce the negative externalities generated by urban air pollution or peak urban travel demand in excess of available supply or road capacity, through artificially restricting demand (vehicle travel) by rationing the scarce common good road capacity, especially during the peak periods or during peak pollution events. This objective is achieved by restricting traffic access into an urban cordon area, city center (CBD), or district based upon the last digits of the license number on pre-established days and during certain periods, usually, the peak hours.

The practical implementation of this traffic restraint policy is common in Latin America, and in many cases, the road rationing has as a main goal the reduction of air pollution, such as the cases of México City, and Santiago, Chile. São Paulo, with a fleet of 6 million vehicles in 2007, is the largest metropolis in the world with such a travel restriction, implemented first in 1996 as measured to mitigate air pollution, and thereafter made permanent in 1997 to relieve traffic congestion. More recent implementations in Costa Rica and Honduras have had the objective of reducing oil consumption, due to the high impact this import has on the economy of small countries, and considering the steep increases in oil prices that began in 2003. Bogotá, Quito, and La Paz, Bolivia also have similar driving restriction schemes in place.

After a temporary implementation of road space rationing to reduce air pollution in Beijing during the 2008 Summer Olympics, local officials put in place several permanent rationing schemes to improve the city's air quality. As of June 2016, another 11 Chinese cities have similar restriction schemes in place. Also, temporary driving restrictions to reduce cars on the streets by half during severe pollution events have been implemented in Paris and surrounding suburbs in March 2014, March 2015, and December 2016; in Beijing twice in December 2015, and one more time in December 2016; and also in Rome and Milan for several days in December 2015. A similar alternate-day travel temporary scheme was implemented in New Delhi as a two-week trial in January 2016. A temporary ban on diesel cars was implemented in Oslo on municipal roads in January 2017.