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SummaryTaxonomy and descriptionFirst principles assesmentEvidence on performancePolicy contributionComplementary instrumentsReferences

Evidence on performance
Bologna Car-Restricted Zone: Zona a Traffico Limitato, Italy
Barcelona Access Control: Poble Sec and La Ribera, Spain
Sao Paulo Number Plate Restriction: Rodizio, Brazil
Athens Odd and Even Number Plate system, Greece (forthcoming)

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

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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.

Context
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 favor 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 certain 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 restriction. 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 are as following:

  • 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. The presence of non-stop access control is that an additional signal confirms validation to those vehicles equipped with an On-Board Unit, but not to vehicles validated via the 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 (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 has been recently 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 in which evening "leisure time traffic" pours out onto the streets and forms long car lines 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 not altered 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 below is completed on the basis of contribution to overall access control policy objectives.

Contribution to objectives

Efficiency

No analysis has been conducted, but the reduction of congestion will have increased efficiency.

Liveable streets

No analysis has been conducted, but the reduction of congestion will have improved liveability.

Protection of the environment

No estimation has been made, but the reduction of congestion will have reduced air and noise pollution and saved the historical buildings, ancient monuments and ruins. 

Equity and social inclusion

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.

Safety

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).

Economic growth

No analysis has been conducted, but the reduction of congestion will have reduced associated costs to the economy.

Finance

Automatic vehicle identification (AVI) technology was used at several entry gates, but with little financial investment.

Practicability

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.


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Barcelona Access Control: Poble Sec and La Ribera, Spain

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The case studies in Barcelona were reported in one of the successful 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.

Context
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 place of the main Olympics events and serve to promote the usage 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 to from 10 am to 10 pm.

The second access control experimentation in the La Ribera scheme has been started from 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, possibly in association with parking services.

Implementation size of Poble Sec and La Rivera is a following table:

 

Poble Sec

La Ribera

Inhabitants inside controlled zone

37,042

4,500

4+ wheeled vehicles inside zone

12,895

2,300

Daily vehicle entries prior to scheme

24,000

2,860

(Hayes et al, 1995)

Impacts on demand
In Poble Sec scheme, a total average daily traffic of 16,106 vehicles was recorded entering the zone during this 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. Following table summarises the average travel time and delay savings compared with the normal July situation. Both average travel time and delay savings were reduced during the period of implementation.

 

Before

During-July

During-August

Average route journey time

19'54"

17'02"

16'02"

Reduction

 

11%

16%

Average delay per route

2'54"

2'23"

2'12"

Reduction

 

18%

24%

(Vera et al, 1993)

In La Ribera scheme, during the hours of access restriction at the main entry, the volume of vehicle entries is reduced by 90%. Whilst during 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 - This result does not make clear the time of "before-and-after"). 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 private vehicles, overall reductions of 24% and 20% respectively, and increased in the 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

Efficiency

The economic efficiency of AVI control technology was shown to compare favourably with manual methods using police. However, the unchanged congestion will have decreased efficiency because of payment of cost.

Liveable streets

Poble Sec scheme can be effective in safeguarding residential areas from being overrun by the private car traffic that is attracted to major events.

Protection of the environment

No estimation has been made, but the reduction of congestion will have reduced air and noise pollution inside zone.

Equity and social inclusion

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.

Safety

By reducing congestion, increased speeds may increase a number of accidents. However, if the low average speeds still remain, the number of accidents will not rise.

Economic growth

No analysis has been conducted, but the reduction of congestion will have reduced associated costs to the economy.

Finance

AVI technology was set in several entry gates, but with little financial investment.

Practicability

Residents living inside the controlled zone expressed high levels of satisfaction with the measures in both Poble Sec and La Ribera. Social acceptance needs to implement these schemes on a permanent basis.

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Sao Paulo Number Plate Restriction: Rodizio, Brazil

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Context
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 by surveys in the city centre area, using the amount of carbon monoxide in the atmosphere as indicator, showed that during the five year-period (1992-1997) only in 36% of the winter days the air quality was considered good. To tackle this problem, CETESB enforced Rodizio in 1995. Also, the City Administration started a similar initiative from 1997.

The two type of Rodizio's 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, Monday prevent the circulation of cars whose number plates have as its last digits either 1 or digit 2. The restriction date 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 at 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 comparing before the adoption of it. 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

Change

Travel time

Morning

21'27"

17'37"

-18%

Afternoon

22'46"

18'42"

-18%

Average Speed

Morning

18.6 km/h

22.8 km/h

23%

Afternoon

17.5 km/h

21.6 km/h

24%

(Biezus and Rocha, 1999)

CET developed the concept of CQL (Congestion Queue Length), implemented from 1991 to quantify traffic congestion. The measurement is based to 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 the adoption of it. The reduction for the period between 7 a.m. and 8 p.m. was 17.7%.

Modal spirit in the Sao Paulo metropolitan region tends to increase the share of car use, adversely to decrease the public transport share during last two decades. The changes in the modal split are that the share of public transport reduced from 45.6% (in 1977) to 33.4% (in 1997), the car rose from 29.1% to 32.2%, while pedestrian trips also rose from 25.2% to 34.3%. The Rodizio period covered the years of 1996 to 1998 showed a consistency with same tendency of the last decades. This means that this phenomenon outweigh the Rodizio. As the volume of licensed vehicles continued to grow a 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 trips by buses was reduced by 5% by controlling the excess bus supply provoked by congestion which is represented by additional vehicles in the bus fleet.


Contribution to objectives

Contribution to objectives

Efficiency

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.

Liveable streets

No analysis has been conducted, but the reduction of congestion should cause improved liveability.

Protection of the environment

The carbon monoxide amount released by vehicles reduced the occurrence of negative and inadequate atmospheric conditions from 14.7% to 3.9%.

Equity and social inclusion

No assessment of equity impacts has been made, but those making occasional journeys off peak during enforcement hours will have benefited.

Safety

By reducing congestion, increased speeds may increase a number of accidents. However, if the low average speeds remain, the number of accidents will not rise.

Economic growth

No analysis has been conducted, but the reduction of congestion will have reduced associated costs to the economy.

Finance

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.

Practicability

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 implement a similar scheme of permit systems. More than 40 cities have introduced traffic-limited zone in Italy (Topp and Pharoah, 1994). Although some local governments or researchers published the report of the 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 those most cases have been continued to enforce. The impact of regulatory restrictions will be potentially likely to erode during long term. Continued effort is needed in the long term.

Permit systems are usually implemented as one of mixed car use restrictions instruments, so that this could explain the lack of up to date knowledge relating to permit systems as an independent measure.

 

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Text edited at the Institute for Transport Studies, University of Leeds, Leeds LS2 9JT