Road space rationing

Road space rationing (Restricción vehicular; Rodízio veicular) is a travel demand management strategy aimed to reduce the negative externalities generated by 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. 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 restriction schemes in place. After a temporary implementation of road space rationing to reduce air pollution in the city during the 2008 Summer Olympics, Beijing has implemented several rationing schemes to improve the city's air quality.

Historical background
The earliest known implementation of road space rationing took place in Rome, as carriages and carts pulled by horses created serious congestion problems in several Roman cities. In 45 B.C. Julius Caesar declared the center of Rome off-limits between 6 a.m. and 4 p.m. to all vehicles except for carriages transporting priests, officials, visitors, and high ranking citizens.

Applications of road space rationing


Road space rationing based on license numbers has been implemented in cities such as Athens (1982), Santiago, Chile (1986 and extended 2001), México City (1989), Metro Manila (1995), São Paulo (1997), Bogotá, Colombia (1998), La Paz, Bolivia (2003), San José, Costa Rica,  (2005)  countrywide in Honduras (2008), and Quito, Ecuador (2010). All these cities restrain a percentage of vehicles every weekday during rush hours or for the entire day. When the restriction is based in two digits a theoretical 20% reduction of traffic is expected. Cities with serious air quality problems, such as México City and Santiago use more digits to achieve greater reductions in air pollution, and even the prohibition can be for more than one day a week. In Bogotá, Colombia from 2009 the plate restriction was extended from peak periods to the whole day (from 06:00 to 20:00 hours) in the whole city, due to the extensive construction sites in public spaces.

Bertrand Delanoë, the mayor of Paris, proposed to impose a complete ban on motor vehicles in the city's inner districts, with exemptions only for residents, businesses, and the disabled, as a three-part plan to implement during a seven-year period. This proposal was made in 2005, in the context of Paris' bid to host the 2012 Summer Olympics which ended up being won by London.

During the discussions regarding the proposal to introduce congestion pricing in New York, the commission created in 2007 by the New York State Legislature to evaluate other traffic relief options, considered road space rationing based on license plates as an alternative to congestion pricing. The proposal stalled in April 2008 as the legislature decided not to vote the proposed plan.

Beijing 2008
On July 20, 2008, Beijing implemented a temporary road space rationing based on plate numbers in order to significantly improve air quality in the city during the 2008 Summer Olympics. Enforcement was carried out through an automated traffic surveillance network. The rationing was in effect for two months, between July 20 to September 20, as the Olympics were followed by the Paralympics from September 6 until 17. The restrictions on car use was implemented on alternate days depending on the plates ending in odd or even numbers. This measure was expected to take 45% of the 3.3 million car fleet off the streets. In addition, 300,000 heavy polluting vehicles were banned from July 1, and the measure also prohibited access to most vehicles coming from outside Beijing. Authorities decided to compensate car owners for the inconvenience, by exempting them from payment of vehicle taxes for three months. A pilot test was conducted in August 2007 for four days, restricting driving for a third of Beijing's fleet, some 1.3 million vehicles. A 40% daily reduction of vehicle emissions was reported. A previous test carried out in November 2006 during the Sino-African Summit show reductions of 40% in NOx auto emissions.

Post-Olympics permanent rule
The rationing during the Olympics was so successful in cleaning the air and relieving traffic congestion, that a modified version of the restriction was made permanent afterward in October 2008, now banning 20% of the vehicles on a given weekday instead of half the vehicles as implemented during the Olympics. Also a ban on heavy trucks from entering the city during the day was implemented, and the oldest most polluting automobiles,  called "yellow-label" cars, after the sticker fixed to their windshields, are banned from entering the city center. In July 2009 a nationwide car scrappage program was implemented offering rebates for trade in old heavy polluting cars and trucks for new ones.

London 2012
The 2012 Summer Olympics organization, with support from the Mayor of London office, announced in 2007 that they are planning auto exclusion zones around all venues, including London, Birmingham, Manchester, Newcastle upon Tyne, Glasgow and Cardiff. London authorities hope this measure will work as an experiment to change the public's travel behavior, allowing thereafter a shift from automobile to mass transit or bicycling. This severe policy has been publicized as the "First Car-free Olympics". During the peak events, the Olympics expect a crowd of 800,000 people. Those attending will have to travel by public transport, mainly through the Underground, or by bicycle or on foot.

Congestion pricing
Transport economists consider road space rationing a variation of road pricing, and an alternative to congestion pricing, but road space rationing is considered more equitable by some, as the restrictions force all drivers to reduce auto travel, while congestion pricing restrains less those who can afford paying the congestion charge. Nevertheless, high-income users can often avoid the restrictions by owning a second car. Moreover, congestion pricing (unlike rationing) acts "to allocate a scarce resource to its most valuable use, as evinced by users' willingness to pay for the resource". While some "opponents of congestion pricing fear that tolled roads will be used only by people with high income. But preliminary evidence suggests that the new toll lanes in California are used by people of all income groups. The ability to get somewhere fast and reliably is valued in a variety of circumstances. Not everyone will need or want to incur a toll on a daily basis, but on occasions when getting somewhere quickly is necessary, the option of paying to save time is valuable to people at all income levels."

Mobility rights or congestion credits
A more recent idea for automobile travel restrictions, proposed by some transport economists to avoid inequality and revenue allocation issues, is to implement a rationing of peak period travel but through revenue-neutral credit-based congestion pricing. This concept is similar to the existing system of emissions trading of carbon credits, proposed by the Kyoto Protocol to curb greenhouse emissions. Metropolitan area or city residents, or the taxpayers, will have the option to use the local government-issued mobility rights or congestion credits for themselves, or to trade or sell them to anyone willing to continue traveling by automobile beyond the personal quota. This trading system will allow direct benefits to be accrued by those users shifting to public transportation or by those reducing their peak-hour travel rather than the government.