Road space rationing
Road space rationing, also known as alternate-day travel, driving restriction, no-drive days and number coding, 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 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, or district based upon the last digits of the vehicle registration plate 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., 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.
Historical background
The earliest known implementation of road space rationing took place in Ancient 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.Effectiveness
Schemes rationing access based on number plate have mixed results. If used infrequently or temporarily the alternate-day travel policy can have some impact. However, if used as a long term measure, inequality issues might arise, as wealthier people can afford to own two cars with opposite-parity number plates, to circumvent any restrictions, with the second vehicle being often older and therefore more polluting. Cities such as Tehran which have used such schemes are now looking to more sustainable methods of traffic and emissions control, such as low emission zone or traffic limited zones as used in Europe. Access regulations have often been found to be effective, in reducing congestion, traffic and pollution.The program's impact on moving behavior to more sustainable transport methods is also unclear. Evaluations on the effectiveness of road space rationing regulations focus mainly on whether there is a decrease in the usage of the less sustainable vehicles for which the schemes were implemented in the first place. They do not focus on whether there is a change in the pattern in which such vehicles are used. For example, evaluations examine how many people stop using a polluting car. They do not evaluate how many people start riding bicycles or carpool as a result of such schemes.
Evaluating effectiveness
It is important to better understand the effectiveness of the regulatory policies intended to reduce traffic congestion to improve their implementation in the future. Some factors that hinder the effective program evaluation of policies like road space rationing are that transportation demand management strategies are often implemented as a part of other broader policies. It is difficult to separate the effects of such methods from the other methods they are associated with. Most measures are taken at the beginning and during the implementation of a strategy. Not enough evaluation is conducted after strategy implementation. In developing countries, data insufficiency hinders the formation of generalizable conclusions on the effectiveness of a strategy. It is hard to outline a cause and effect relationship between the regulation that is implemented and the change in behavior it creates or general effect it has. Many factors could cause a change in the behavior of individuals affected by the regulation at hand. It could be the direct result of that regulation or the result of other existing regulations, and societal effects. Given that such programs are not usually implemented in isolation, singular conclusions on the effectiveness of regulations impacting traffic congestion are difficult to form.Three methods can be employed to measure the effectiveness of regulatory policies. The first measure, administration evaluation, examines how road space rationing is delivered and enforced to the target audience. The second measure, behavioral evaluation, focuses on the extent to which the regulation changes the behavior of the target audience. The third measure, outcome performance, analyzes the outcomes of the regulation. To collect information on these measures, direct observation, stated preferences surveys, and revealed preference surveys can be conducted. These methods can be conducted in isolation or simultaneously to procure rich data. The problems associated with these methods are observer bias in direct observation, the spread of misinformation when respondents are untruthful, and excess time consumption.
Applications of road space rationing
Permanent alternate-day travel schemes
Road space rationing based on license numbers has been implemented in cities such as Athens, Santiago, Chile, México City, Metro Manila, São Paulo, Bogotá, Colombia, La Paz, Bolivia, San José, Costa Rica, countrywide in Honduras, and Quito, Ecuador. 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 in the whole city.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.
Athens
Rising traffic in Athens during the 1990s led to the development of the Dactylius around central Athens. The Dactylius does not require drivers to pay in order to enter the areas subjected to the Dactylius' restrictions. Instead, the scheme depends on the parity of the date and of the vehicle's registration plate, the vehicle type as well as the time of the week/month. There are three Dactylius areas: The Inner, the Outer and the Green, each one with its own policies.Bogotá
Then mayor Enrique Peñalosa, introduced in Bogotá, Colombia in 1998 a driving restriction program, "Pico y placa" to reduce traffic congestion during rush hours. The system restricts traffic access into a pre-established urban area for vehicles with license plate numbers ending in certain digits on pre-established days and during certain hours based on the last digit of the licence plate numbers. Initially the system restricted traffic between 7:00 and 9:00 a.m. and between 5:30 and 7:30 p.m., Monday through Friday, for two days for each registered vehicle.Then mayor Antanas Mockus extended the restriction for one hour in 2001. A complementary program called "El Pico y Placa Ambiental" was implemented by then mayor Luis Eduardo Garzón in 2006, expanding the restriction to public transportation vehicles, including both bus and taxi services. Four numbers were restricted every day for private use vehicles, and two for public transportation vehicles. Since 2002 Bogotá's scheme switched the combinations of days and numbers every year, making it harder to circumvent the restriction by buying another car.
Starting in February 2009, then mayor Samuel Moreno Rojas extended the restriction from 6 a.m. to 8 p.m., Monday through Friday. This extension was issued as a temporary measure until public works related with the Transmilenio BRT were completed. In July 2012, then mayor Gustavo Petro reduced the hours of the restriction from 14 to 7 hours per day, to restrict access only between 6:00 and 8:30 a.m. and between 3:00 and 7:30 p.m. In addition, five neighborhoods were released from the restriction, Usme, Rafael Uribe Uribe, Tunjuelito, San Cristóbal and Ciudad Bolívar. Also, under the modified scheme five ending numbers are restricted every day between Monday and Friday, license plated ending on odd-numbers are restricted on odd-days of the month, and even-numbers on even-days.
Since December 2014, exempted vehicles include passenger cars with three or more passengers including the driver; properly registered vehicles for use by people with disabilities; all-electric vehicles; emergency vehicles, such police cars, ambulances, and fire trucks; properly identified public utilities vehicles, traffic control and towing vehicles; school buses; motorcycles; cash-in-transit armored vehicles; funeral vehicles; and press, judiciary, diplomatic, presidential motorcade, and security escort vehicles.
Similar schemes with the same name have been implemented in several Colombian cities, including Armenia, Barranquilla, Bucaramanga, Cali, Cartagena, Manizales, Medellín, and Pereira.