Regulatory Restrictions

This measure was updated by INSTITUTE FOR TRANSPORT STUDIES (ITS) in 2014 under the CH4LLENGE project, financed by the European Commission.

Two principal types of regulatory restriction exist: permit systems in which only designated vehicles are allowed to enter an area and number plate restrictions which prohibit certain number plates on certain days.  Permit systems are typically permanent, while number plate restrictions can be operated permanently or only when conditions require.  Both types of control can be operated manually, but more often use access control technology for administration and enforcement.

The principal objective is usually environmental, in reducing pollution, noise, and adverse impacts on historical city centres.  However, the restrictions can also reduce congestion and accidents and enhance the local economy.  Restrictions may cause inequities unless those unable to use their cars are given alternatives.  There is also potentially the risk that traffic will be diverted to adjacent areas.  The principal barriers are legal requirements and political and public acceptability.

Evidence on permit schemes indicates that they are effective in reducing traffic levels and pollution, and do not appear to transfer problems elsewhere.  However, their benefits can be eroded by lax control of permit issue and ineffective enforcement. Evidence on number plate restrictions is less promising.  The ability of car owners to acquire a second vehicle means that traffic reductions are typically far lower than anticipated.  Generally there is a dearth of information on the long term impacts of these measures on the economy and equity.


Regulatory restrictions aim to limit car use in urban areas by means of access control into a particular area (often a city centre). "Regulatory" means legal measures based on the road traffic laws or the air pollution control laws but not including the pricing methods like urban road charging or physical restrictions such as road space reduction. Freight vehicles like the lorry may be exempted from regulatory restrictions. The lorry may also be controlled by other measures covered in Lorry routes and bans. Although the concept of "Car-free" or "Car-limited" zones are included in regulatory restrictions, they also contain physical restrictions on car use and an improvement in the environment for pedestrian areas.

Types of Regulatory Restrictions

Two main types are in use: permits and number plate restrictions.

Permit systems operate to ban certain types of traffic from entering a defined area during specific time periods by the issue of permits. Usually private vehicles from outside the area and through traffic are discouraged, whilst residents' vehicles within the area and service and commercial vehicles are usually exempted from restrictions since they can be justified to be essential in a city centre. The categories of vehicles and people who qualify for such exemptions are determined by local or municipal authorities.

Number plate restrictions are usually operated as the odds and evens system, in which vehicles with odd number plates and those with even number plates are admitted on alternate days determined by a day of the week or date. The system in Sao Paulo is based on the last digit of the number plate, where for example the vehicles prohibited from driving on Monday are those whose number plates have as their last digits either 1 or 2. Some categories of vehicles and people are also exempted from number plate restrictions.

Number plate ending on odd number Number plate ending on even number

Both types are implemented not only permanently but also temporarily. The permanent measures are usually operated either on weekdays or at the weekend or every day. The temporary measures are implemented on days in excess of a threshold of air pollution levels, or for specific events such as a Car-free day. Number plate restrictions are usually used for the temporary measures because they are easier to enforce than permit systems. Hours of enforcement are usually working hours (e.g. 9:00 a.m. to 5:00 p.m.), but sometimes are only morning and evening peak hours.


Regulatory restrictions specify whether a given vehicle is allowed to drive in a defined area. The design of the checking points into and within an area is very important. When temporary regulatory restrictions are implemented during a specific time such as one day or a specific period like one season, municipal police or the authority establish access control points at the entrances into a given area wide or on screenlines within it and check the number plate or the category of vehicles to be permitted. Most applications of permanent measures (often permit systems) are based on point checking in which a check is operated on the entrance into the area by using paper licences. Conventional message signs are also used to alert drivers. This traditional system is operated in many cities. Simplicity of administration, prevention of misuse and ease of enforcement have to be considered when using such low technology options.

An applicable access control technology was developed in the 1990s and operated in some European cities. Drivers who have a permit can pass the toll without stopping. There are a number of options for technologies (Miles et al, 1998):

Video-based systems

Video-based systems - Optical Character Recognition (OCR) and a permitted list. Use of number plate recognition requires suitable camera positions to provide number plate visibility and adequate lighting. For example, the number plate of a car following close behind a large vehicle may never be in the direct view of the camera.

Sophisticated non-stop tolling technology with communications capable of handling large data volumes at very high vehicle speeds. These systems are very effective, but environmentally intrusive and costly. Vehicles must be equipped with on-board transceivers or tags and video enforcement is also necessary, so implementation costs are high.

Simpler methods of selective vehicle detection as used for bus priority may be adequate if the numbers to be equipped are relatively small.

Magnetic smart card

A magnetic or smart card pass that has to be manually inserted by the driver into a slot or through a contactless reader is a cheap but slow option.

Barcode sticker

A barcode sticker and reader located at the side of the road uses established technology, but is likely to be slow.

Similar technologies are reviewed in urban road charging.

Why introduce regulatory restrictions?

Regulatory restrictions on car use aim to reduce  traffic congestion and improve traffic flow in urban areas. Reducing the volume of vehicles also aims to improve the quality of environment and the level of air pollution. There are many ways of reducing congestion for car travel. Regulatory restrictions are often easier to influence than other measures to reduce car use in urban areas. Physical restrictions are sometimes difficult to implement given the urban fabric or structure. If the city lacks adequate ring roads regulatory restrictions are better ways to reduce through traffic in a city centre. Urban road charging is likely to be less publicly acceptable.

Demand impacts

The demand impacts of regulatory restrictions are mainly on the demand for car travel and demand for alternatives. Most changes in the demand are decreases for car travel and conversely increases for public transport, walking and cycling. The demand response is different by type of measure: permit systems or number plate restrictions. It also depends on the service level of public transport. This will contribute to transport policy objectives seeking to reduce congestion and the associated negative impacts.

Responses and situations
Response Reduction in road traffic Expected in situations
Where the system operates during limited hours such as peak periods.
Where the drivers need to park outside the area or divert around it.
Not applicable.
Where there is potential to work, shop etc from home.
Where public transport is available and attractive and there is potential to walk or cycle.
Where modal shift and/or reduction in number of journeys makes owning a car uneconomic,  But with licence plate controls some people buy second cars.
If people may move house into the defined area to avoid the regulation.
= Weakest possible response = Strongest possible positive response
= Weakest possible negative response = Strongest possible negative response
= No response

Short and long run demand responses

Demand responses



1st year

2-4 years

5 years

10+ years

= Weakest possible response = Strongest possible positive response
= Weakest possible negative response = Strongest possible negative response
= No response

Supply impacts

There will be no increase in the supply of road space, except where regulatory restrictions include additional provision for alternatives, for example promoting public transport, providing parking lots and facilities for walking and cycling.

Financing requirements

Operating regulatory restrictions needs many enforcement staff for the checking the validity of vehicles' permits unless access control technology is used. This may particularly happen where this measure is implemented on occasional days such as air pollution emergencies or a Car-free day. Permanent permit systems impose a cost to issue permits. Access control technology requires investment together with costs for the administration and enforcement of the technological system.

Expected impact on key policy objectives

Regulatory restrictions are implemented to reduce traffic congestion and to develop sustainable mobility. They encourage people to reduce their overall level of car-use in the city centre by switching from car to other transport modes. Also, they will contribute to a liveable and attractive city centre. However, a large number of permits and weak enforcement will not achieve these benefits.

Contribution to objectives


Scale of contribution



By reducing delays and improving reliability. Contribution may be greater where promotion is accompanied by park and ride or an improvement in public transport service levels.


By improving streetscape and by reducing community severance; but outside of a defined area may be worse because of diverted traffic.


By reducing air and noise pollution and pressures on green space and environmentally sensitive sites; but outside of a defined area may be worse because of diverted traffic.


By improving public transport conditions; but there are often many exemptions based on unclear justification, making it an inequitable measure.


By reducing traffic levels.


By freeing up potentially productive time currently lost in congestion and by enabling freight operators to rationalize their fleet operations.


There are operating costs for checking the validity of permits, but fines on violating vehicles may help offset these costs.

= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Expected impact on problems

Regulatory restrictions will reduce car use in the defined area, hence they have the potential to contribute to the alleviation of a number of key problems.

Contribution to alleviation of key problems


Scale of contribution



By reducing traffic volumes in a defined area, but potentially offset by increasing diverted traffic outside an area.
Community impacts By reducing traffic volumes in a defined area, but potentially offset by increasing diverted traffic outside an area.
Environmental damage By reducing traffic volumes in a defined area, but potentially offset by increasing diverted traffic outside an area.
Poor accessibility By enhancing the reliability of public transport and by discouraging car-oriented development in a city centre.
Social and geographical disadvantage By enhancing the reliability of public transport and reducing traffic levels in a defined area.
Accidents By reducing traffic volumes in a defined area, but potentially offset by increasing diverted traffic outside an area.
Economic growth By improving the efficiency of the local road network through reduced congestion.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Expected winners and losers

Those who are exempted from restrictions should benefit from reduced congestion. However, there can be many winners if effective measures of public transport and parking management are included as part of a package.

Winners and losers




Large scale freight and commercial traffic

High value journeys - less time spent in congestion the greater the vehicle utilization - relatively small proportion of journey distance in urban conditions. In addition, usually exempted from restrictions.

Small businesses

Where these are local and reduced car use encourages use of local amenities. However, where vehicles are prohibited from entering may become less attractive in city centre.

High income car-users

High income associated with high value of time and thus continued car use for high value journeys by sometime purchasing a second car or permitted car. These journeys will benefit from reduced congestion.

People with a low income

Where prohibited or restricted entering their vehicles into the city centre. This may reduce congestion, but not solve problems associated with low income car users.

People with poor access to public transport

Reduced congestion will improve public transport reliability, but not solve problems associated with poor access for public transport users.

All existing public transport users

Reduced congestion will improve public transport reliability. In addition, increased demand for alternatives may result in increased quality and volume of service.

People living adjacent to the area targeted

Where prohibited or restricted the city centre and as a result of increases in diverted traffic in the peripheral area.

People making high value, important journeys

These journeys will have higher values of time and may continue to be made by car and ideally be exempted from restrictions.

The average car user Where they may benefit from reduced congestion.
= Weakest possible benefit = Strongest possible positive benefit
= Weakest possible negative benefit = Strongest possible negative benefit
= Neither wins nor loses

Barriers to implementation

Scale of barriers
Barrier Scale Comment
Legal Regulatory restrictions require legislation and detailed specification of regulations and exemptions may prove complex.
Finance Costs of investment in access control technology, administration and enforcement.
Governance These will depend on whether a single local authority is responsible.  Often higher level authorities need to approve such measures.
Political acceptability Regulatory restrictions will be highly sensitive politically, but may be seen as a more acceptable alternative than pricing.
Public and stakeholder acceptability There is likely to be strong opposition from affected car users.
Feasibility Access control technology and the establishment of administrative and enforcement procedures can present problems.
= Minimal barrier = Most significant barrier

Bologna Car-Restricted Zone: Zona a Traffico Limitato, Italy

Display location

Topp and Pharoah (1994) report the impacts of a car-restricted zone in Bologna. Cairns et al (1998) provide the evidence of Bologna as a case study. TRANSLAND (1999), the EU research project in the field of integrated transport and land-use planning, also covers Bologna as a case study for good planning practice.


Bologna is a large historic centre with narrow and irregular streets and has the old town encircled by a large four-lane ring road. First attempts at traffic limitations began in 1972, including the introduction of a pedestrian area and bus lanes, and restrictions on private vehicle movements. In 1984, a new comprehensive plan was introduced by a referendum, in which 75% of Bologna residents voted in favour of the selective restriction of the city centre for private automobile traffic. This plan included access control to the old town, parking management and extension of the pedestrian area.

In 1989, the car-restricted zone "Zona a Traffico Limitato", which contains the entire old town, was introduced as a permanent regulation. Access by motor vehicle was restricted between 7 a.m. and 8 p.m., except for the following categories of vehicle having access permits*:

  • buses of the public transit operations;
  • taxis and emergency service vehicles;
  • residents cars (about 25,000);
  • vehicles of trade business and shop owners located in the city;
  • delivery vehicles (only at set times) (about 15,000);
  • hotel guests from outside the Bologna region;
  • holders of private parking spaces.
    (*List based on TRANSLAND (1999) and complemented from Topp and Pharoah (1994))

The access control was supplemented by other measures including parking restrictions. There is only one large public car park for long stay and residents are allowed to park only in their own quarter. However, thousands of park-and-ride spaces were built outside the ring road, together with additional free parking for transit pass holders or bicycle owners. Other implemented measures were:

  • extension of the short term parking zones on the edge of the historical centre;
  • introduction of a 30 kilometre per hour speed limit in the entire restricted area;
  • re-organization of the municipal bus transit services;
  • strict surveillance of access through parking control;
  • extension of the pedestrian zone at the expense of an arterial road.
    (TRANSLAND, 1999)

The twelve entry gates into the historical centre were only marked with signs showing restricted access to alert drivers. In 1994, the first five access gates installed a telematic system. Under non-stop access control  an additional signal confirms validation to those vehicles equipped with an On-Board Unit, but not to vehicles validated via  Optical Character Recognition (OCR). This telematic system provides flexibility for handling non-equipped vehicles. For example, a car driver staying at a hotel inside the controlled zone registers the vehicle number plate when checking in, and this is then relayed to the control centre to suppress the issue of a fine.

Impacts on demand

The local government provided the data: the total number of vehicles (and of cars excluding taxis) entering and leaving daily the old town was reduced from 177,000 (152,000) in 1981 to 87,000 (58,000) in 1989. The reduction of all vehicles was 49% and private cars dropped by 62%. This was achieved without major traffic increases on the ring road, though through traffic was reassigned to the ring road. However, car limitation was subsequently eroded because the large number of permits and weak enforcement led to increases in traffic (Topp and Pharoah, 1994).

Bus transport achieved shorter journey times and provided more punctual service because of less traffic on the bus routes in the old town. Bicycle, taxi and motorcycle traffic has grown. In 1990, the modal split for those visiting the old town was approximately 78% bus, 11% private cars and 8% bicycle or motorcycle. The modal split for trips within Bologna is 31% walking, 2% bicycle, 33% public transport and 34% private cars.

The restrictions end at 8 pm, after which evening "leisure time traffic" pours out onto the streets and forms long queues through the old town and ruins evening walks (TRANSLAND, 1999).

Impacts on supply

The supply of road space has not changed as a result of the car-restricted zone. However, more recently, the local government has undertaken a series of actions:

  • development and upgrading of fringe park and ride nodes;
  • development of new parking lots in the intermediate periphery and operation of shuttle lines for old town connections;
  • promotion of public transit use by: i) enlarging and updating the vehicle fleet (including electric vehicles), ii) redesigning the public transit circulation, iii) modernizing the bus shelters, iv) implementing the tele-monitoring system for prompt user information on schedules and traffic situation, v) improving user information on prices, services and intermodal opportunities;
  • development of new bicycle infrastructure (parking and reserved lanes).
    (TRANSLAND, 1999)

Contribution to objectives

Bologna encompasses the historical city centre, which is unaltered since the 13 century and was built for pedestrian traffic. This may raise the quality of life and livelihood of the city centre for both residents and visitors.

Contribution to objectives

Objective Comment
  No analysis has been conducted, but the reduction of congestion will have increased efficiency.
  No analysis has been conducted, but the reduction of congestion will have improved liveability.
  No estimation has been made, but the reduction of congestion will have reduced air and noise pollution and helped save the historical buildings, ancient monuments and ruins.
  Improvements in bus transport, bicycle and motorcycle services have made the transport environment more equitable and reduced the potential for social exclusion through lack of access to a car.
  The reduction of congestion with no significant increase in speeds will have improved safety for pedestrians, cyclists and cars travelling next to each other. Average speeds in the old town can rarely exceed 15 km/h, with the 30 kilometre per hour speed limit as a supplementary measure (TRANSLAND, 1999).
  No analysis has been conducted, but the reduction of congestion will have reduced associated costs to the economy.
  Automatic vehicle identification (AVI) technology was used at several entry gates, but with little financial investment.
  In the 1984 referendum, most public supported the measure. This measure also contained strong involvement of the municipal police and involved appointing new officers for strict surveillance of access. Strong public and institutional supports enabled the local government to plan and implement traffic restriction.

Barcelona Access Control: Poble Sec and La Ribera, Spain

Display location

The case studies in Barcelona were reported in the GAUDI (Generalised and Advanced Urban Debiting Innovations) project. Vera et al (1993) report the first of the Barcelona experimentations Poble Sec, and Hayes et al (1995) and Miles et al (1998) summarized the impact of access control systems and tools applied in some cities, including Barcelona.


The Poble Sec scheme during Olympic Games from 25 July 1992 to 9 August 1992 was to protect a residential neighbourhood from visitor car traffic attempting to park near the site of the main Olympics events and serve to promote the use of public transport. In this scheme, residents and other authorized vehicles were provided with permits for entry to the zone during the period of the Olympics. Many of the access streets to the restricted zone were closed, and access control applied to the remaining four entry points. The scheme was based on manual enforcement with the registration of automatic tag transactions to reduce the task of validating identifiers. The control measures were imposed from 10 am to 10 pm.

The second access control experimentation in La Ribera  started in January 1995. The scheme focused on the promotion of street space for pedestrians and other non-vehicle users. Only authorized vehicles were permitted to gain access and the configuration incorporated a retractable bollard to prevent unauthorised vehicles from entering. Vehicle owners received authorisations on smartcards which were inserted into on-board units which communicated with roadside equipment. Entry points for the scheme have been located on the secondary road network where traffic intensities are low enough for a bollard-based enforcement solution to be considered. The bollard control was employed clearly to promote the concept of pedestrian priority in a way that serves to calm traffic. Enforcement hours are peak hours: 11 am to 2 pm and 5 pm to 8 pm. In 1996, the La Ribera scheme was extended to provide priority access/loading space for delivery vehicles, in association with parking services. 

The scale of the two schemes is shown in the following table.

Implementation size of Poble Sec and La Rivera


Poble Sec

La Ribera

Inhabitants inside controlled zone



4+ wheeled vehicles inside zone



Daily vehicle entries prior to scheme



(Hayes et al, 1995)

Impacts on demand

In the Poble Sec scheme, a total average daily traffic of 16,106 vehicles was recorded entering the zone during the controlled period. This compares with a total volume of 24,131 per day which entered the zone on a weekday in July prior to the introduction of the restrictions. This indicates a reduction in demand of 33% with respect to the conditions experienced in the zone. The following table summarises the average travel time and delay savings compared with the normal July situation. Both average travel time and delay were reduced during the period of implementation.





Average route journey time








Average delay per route








(Vera et al, 1993)

In the La Ribera scheme, during the hours of access restriction, the volume of vehicles entering was reduced by 90%. Including times of unrestricted access results in a 78% reduction over working day. The analysis of before-and-after on-street parking showed that occupancy levels have increased during the morning hours prior to the restriction both inside and outside the zone. (Hayes et al, 1995). Although residents perceive a reduction in traffic congestion inside the zone, delays in the zone were negligible both before and after. The border area also shows no significant change in journey time. Both La Ribera residents and visitors report reductions in the use of private vehicles, overall reductions of 24% and 20% respectively, and increased use of public transport and walking and cycling (Hayes et al, 1995).

Impacts on supply

Road capacity has been maintained, but access control gates were installed with Automatic Vehicle Identification (AVI) technology. In the La Ribera scheme at the first principal entry site, space at the junction was sufficient to enable an island to be introduced so as to separate vehicles wishing to enter from the rest of the circulating traffic.

Contribution to objectives

Contribution to objectives

Objective Comment
  Reductions in congestion will have increased efficiency, but this will be offset in part by the additional costs of using alternative modes and routes.
  Poble Sec scheme can be effective in safeguarding residential areas from being overrun by the private car traffic that is attracted to major events.
  No estimation has been made, but the reduction oftraffic will have reduced air and noise pollution inside zone.
  Improvements in public transport have made the transport environment more equitable and reduced the potential for social exclusion through lack of access to a car.
  No analysis has been conducted.  If congestion is reduced, increased speeds may increase a number of accidents. However, if the low average speeds still remain, the number of accidents will not rise.
  No analysis has been conducted, but the reduction of congestion will have reduced associated costs to the economy.
  AVI technology was set in several entry gates, but with little financial investment.
  Residents living inside the controlled zone expressed high levels of satisfaction with the measures in both Poble Sec and La Ribera. Social acceptance is needed to implement these schemes on a permanent basis.

Sao Paulo Number Plate Restriction: Rodizio, Brazil

Display location


A number plate restriction program called "Rodizio" in Sao Paulo is reported by Biezus and Rocha (1999). CETESB (Companhia de Saneamento Basico do Estado de Sao Paulo - Sao Paulo State's environmental agency) conducted surveys in the city centre area, using the amount of carbon monoxide in the atmosphere as an indicator, and showed that during the five year-period (1992-1997) only on 36% of the winter days was the air quality considered good. To tackle this problem, CETESB inroduced Rodizio in 1995. Also, the City Administration started a similar initiative from 1997.

The two types of Rodizio scheme are as follows, (a) CETESB and (b) City Administration:

Area covered:
(a) Part of the Sao Paulo Metropolitan Region (10 municipalities of the Greater Sao Paulo)
(b) The centre of Sao Paulo (area within the inner ring road)

Enforcement period:
(a) July to September
(b) February to June and October to December

Restrictions in force:
20% of the licensed vehicle fleet for each workday.
The restriction is based on the last digit of the number plate. Every working day corresponds to the restriction of two digits. For example, on Mondays the circulation of cars whose number plates have as their last digit either 1 or 2 is prohibited. The restricted day is shifted every month.

Hours of enforcement:
(a) Working time: 7 am to 8 pm.
(b) Peak hours: 7 am to 10 am and 5 pm to 8 pm.

Impacts on demand

CET (The city's traffic management agency) conducted a survey of traffic volume in peak time on seven important avenues of the city between October 1997 and March 1998. The result was a reduction in the hourly volume of 2% during the AM peak and 5% during the PM peak during the Rodizio compared with before its adoption. CET also conducted a field survey to monitor traffic performance on two major city avenues during the same period. The following table indicates the improvement in both travel time and the average speed.


Before the Rodizio

During the Rodizio


Travel time









Average Speed


18.6 km/h

22.8 km/h



17.5 km/h

21.6 km/h


(Biezus and Rocha, 1999)

CET developed the concept of CQL (Congestion Queue Length), implemented from 1991 to quantify traffic congestion. The measurement is based on the empirical distinction between traffic categories: free-moving, slow, stop-and-go and standing still. The CQL is defined by the sum of the queue lengths of the latter three categories. Average CQL during the Rodizio was 37% in AM peak and 26% in PM peak lower than before its adoption. The reduction for the period between 7 a.m. and 8 p.m. was 17.7%.

Car use in the Sao Paulo metropolitan region had been increasing and public transport use falling during the previous two decades. The share of public transport fell from 45.6% (in 1977) to 33.4% (in 1997); car use rose from 29.1% to 32.2%, while pedestrian trips also rose from 25.2% to 34.3%. The Rodizio period covering the years of 1996 to 1998 continued the same trend. As the volume of licensed vehicles continued to grow at the same rate after implementation of Rodizio, Biezus and Rocha (1999) have some concerns that the permanent adoption of the Rodizio will lead to an additional car for each household with a different number plate.

Impacts on supply

There is no change to the supply of road space. The number of buses movements was reduced by 5% by controlling the excess bus supply required by congestion.

Contribution to objectives

Contribution to objectives

Objective Comment
  The reduction of congestion (CQL) resulted in an increase in average speeds and a decrease in travel time. There were substantial reductions in congestion costs and increases in benefits.
  No analysis has been conducted, but the reduction of congestion should improve liveability.
  The carbon monoxide amount released by vehicles reduced the occurrence of negative and inadequate atmospheric conditions from 14.7% to 3.9%.
  No assessment of equity impacts has been made, but those making occasional journeys off peak during enforcement hours will have benefited.
  No analysis has been conducted, but the reduction of congestion should improve liveability.
  No analysis has been conducted, but the reduction of congestion will have reduced associated costs to the economy.
  There is no evidence regarding costs, but it is thought that local government needs to pay surveillance costs for checking the validity of number plates.
  Nor reported, but it is thought that local government needs to establish a new air pollution control law.

Gaps and weaknesses

A number of European cities have implemented  similar permit systems. More than 40 cities have introduced traffic-limited zones in Italy (Topp and Pharoah, 1994). Although some local governments or researchers presented evidence relating to impacts, these reports include only the impacts in the short or middle term. There are gaps in our knowledge of long-term impacts despite continued operation in most cases. The impact of regulatory restrictions will be potentially likely to erode in the long term. Continued effort is needed to sustain their impacts in the long term.

Contribution to key objectives

Contribution to key objectives



Sao Paulo

= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Contribution to alleviation of key problems

Contribution to alleviation of key problems



Sao Paulo

Community impacts
Environmental damage
Poor accessibility
Social or geographic disadvantage
Economic growth
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Appropriate contexts

Regulatory restrictions are applicable to any city, but implementation will be more acceptable in cities where:

  • there is a critical problem of traffic congestion
  • there is (or there is provision for) a good public transport network
  • it is not easy to increase the road network capacity for the urban fabric or structure
Appropriate area-types
Area type Suitability
City centre
Dense inner suburb
Medium density outer suburb
Less dense outer suburb
District centre
Small town
Tourist town
= Least suitable area type = Most suitable area type

Adverse side-effects

The main adverse side effect in number plate restrictions is the encouragement to buy an additional car. This is likely to encourage more congestion than there would have been without implementation. In permit systems, the extension of the ring-shaped connecting streets on the periphery of a restricted area would have the unfavourable side effect of accelerating and attracting car traffic. These are measures which lead in the opposite direction to car use reduction principles.

Biezus, L. and Rocha, AJO. (1999) Does congestion management improve public transit? Logos Engenharia.

Cairns, S., Hass-Klau, C. and Goodwin, P. (1998) Traffic of highway capacity reductions: assessment of the evidence. London, Landor Publishing.

Goddard, H. (1997) Using tradable permits to achieve sustainability in the world's large cities. Environmental and Resource Economics 10 63-99.

Hayes, S., Gascon, O., Crespo, J., Bonora, S. and Gazzotti, F. (1995) Generalised and advanced urban debiting innovations: The GAUDI Project 4. Vehicle access control tools for demand management. Traffic Engineering and Control 36(6) 362-368.

Miles, J., Walker, J., Macmillan, A. and Routledge, I. (1998) Access control in city centres: objectives, methods and examples. Traffic Engineering and Control 39(12) 648-654.

Ogunsanya, A.A. (1984) Improving urban traffic flow by restraint of traffic: The case of Lagos, Nigeria. Transportation 12(2) 183-194.

Topp, H. and Pharoah, T. (1994) Car-free city centers. Transportation 21(3) 231-247.

TRANSLAND (1999) Bologna, Italy: Restriction of automobile traffic in the historical center.

Vera, P.E., Hayes, S. and Burgell, J. (1993) Findings from a GAUDI: Zone access control field-trial in Barcelona. Traffic Engineering and Control 34(3) 114-121.