www.curacaoproject.eu                      CURACAO - coordination of urban road-user charging organisational issues                   Funded by the EU

Road Pricing Context













Decision Making



Implementation and Evaluation



Case Studies






Dutch National Case









The Hague


Urban Road User Charging Online Knowledge Base

Comparison of ENVIRONMENT on our case studies


In general, modal split was influenced by all the changes in the city, but the Access Control and Road Pricing Schemes played major roles, as already highlighted. Before and after data show that, in 2002, modal split in the central area was 30% public transport, 27% private cars, 23% motorbikes/mopeds and 20% pedestrians. The 2005 data revealed that these proportions had switched to 31%, 22%, 24% and 23%, respectively. The most important result is the decrease of private cars in favour of three point increase (percentage) for walking, thus suggesting that citizens reduced their use of the car for trips of short distances.


The benefit of the Access Restriction is also evident when traffic flows and illegal through-traffic are considered: the former decreased by 20% during the restriction periods and by 15% in the morning peak hour (8.30-9.30). The proportion of illegal accesses decreased from 18% to less than 10% of the total traffic flows, during the four years of the gates implementation (even though, currently, still about 20.000 vehicles/week illegally access the area).


Data analysis performed during the period between 2006 and 2008 confirmed this trend and also the number of accesses during the same period is resulted quite stable (around 70,000 vehicles/day), except during Christmas time (10th – 20th December) when different ZTL rules have changed the access rate.


The benefit of access restriction is also evident when considering traffic flows and illegal through-traffic: the former decreased by 20% during the overall restriction period and by 15% in the morning peak hours (8.30 – 9.30). Since e-gates were implemented, the proportion of illegal accesses decreased from 18% to less than 10% in respect of total traffic flows. Despite of that still now 20,000 vehicles per week illegally access the LTZ area. The analysis of 2008 data on access violations confirms that about 4,000 fines are emitted during every working day and during the whole year roughly one million of sanctions have been issued. 

Hence, the general objective of reducing the impact of traffic on the environment and increasing the level of protection of the city centre can be considered achieved.

An appreciable reduction in air pollution was measured: the comparison, in terms of concentrations, between the annual mean values, recorded in 2001 and the mean values in 2004 showed a reduction of CO concentration of about 21%, PM10 of 11% and Benzene of 37%. In particular, results concerning benzene concentrations seem to be particularly relevant since, if just 2005 is considered, a 27% decrease was recorded at about 50 sites.

Also emissions strongly decreased and exceeded expectations. The number of polluting vehicles decreased e.g. non-catalysed mopeds reduced by about 45%, private cars by 37% and commercial vehicles by slightly less than 35%. However the main influence on this was a ban on diesel and gasoline fuelled vehicles not meeting Directive 91/441/CE requirements from circulating in the Rail Ring area, which came into force in January 2002.

Regarding the Trastevere and San Lorenzo ACS+RP schemes, pollution concentrations surveyed in the central LTZ and in two districts with passive sampler campaigns are in line with the decrease observed at urban level; the most positive outcomes were recorded at Trastevere rather than at S.Lorenzo, but the different morphology of the two districts along with other factors such as the differences of time of implementation can contribute to such discrepancy.


Even more significant, in the San Lorenzo district, are the results for noise pollution. During the monitoring of area, after the implementation of the measure, in zones without commercial activities a reduction of noise pollution of 8-9 dB(A) was observed. In zones with commercial activities such as restaurant or pubs, the reduction of noise pollution was slight and was about 3-4 dB(A).

A complete analysis was carried out on the basis of the annual mean values in three significant air quality measurement stations of the Regional network, namely:


  • A station located within the historical city centre LTZ (Arenula);
  • A station situated outside the LTZ but in a congested area of the city (Via Magnagrecia);
  • A station placed within a green area outside the LTZ (Villa Ada).

Carbon monoxide (CO) values metered during last ten years show a constant decrease in all three station considered. This is mainly due to cars engines technical improvements and also to mobility management activities introduced.

On the contrary, PM10 value metered during last ten years show a substantial difference between the readings of the city centre station with respect to the other two considered. While these last two had a constant trend during the period between 1998 and 2001, the Arenula station registered a decrease of more than 30% in PM10 concentration between the same period.

This is mainly due to the coming into force of the e-gates in 2001 and it is clearly reflected in the decrease of number of days in which the PM10 concentration overcomes the UE threshold value reached by the Arenula readings with a decrease of more than 50. 

As a preliminary conclusion and by considering that NO2 concentration values do not evidence any definitive behaviour, we could state that the introduction of the LTZ scheme controlled by e-gates has anyway supported Rome Municipality environmental policies.



TfL acknowledges that it is difficult to separate out the direct impact of the Congestion Charge itself on the function of the road network. Improvements to the road network can be attributed to the impact of a wider package of measures, including major projects such as the pedestrianisation of Trafalgar Square, which removed traffic from the northern side of the square in order to improve the urban environment.
Table 2 2 observes the key percentage changes year on year in traffic entering the central London charging zone between 07:00 and 18:30 . The column 2003 vs 2002 shows the immediate impact of the introduction of Congestion Charging in 2003. The gradual variations year on year are also shown as well as the overall change in the last column of the table that compares 2006 with 2002.

Table 2 2 - Key year on year changes in traffic entering the central London charging zone during charging hours (07:00 – 18:30) .

Statistics of note in the above table include the number of cars and minicabs entering the central London charging zone. During charging hours in 2006 this was 36% lower than 2002 i.e. before charging was introduced. Alternatives to car travel such as pedal cycles have become very popular – a 49% increase between 2002 and 2006.

In terms of network speed, TfL notes a fluctuation over time since the introduction of Congestion Charging in 2003. The figure in 2003 was approximately 17 km per hour, compared to 14 km per hour in 2002. More recently, observed charging hour speeds have fallen to 16 km per hour in 2005 and 15 km per hour in 2006. TfL say that modeling suggests that had charging not been introduced, average speeds would have worsened from the 14 km per hour figure in 2002, to approximately 11.5 km per hour by 2006.

The effect of the western extension on traffic volumes and traffic composition is in line with Transport for London’s expectations. Their July 2008 impact monitoring report records that traffic entering the extension zone during charging hours in 2007 (vehicles with four or more wheels) was down by 14%. This level of reduction has been preserved in 2008, and compares with TfL’s expectation for reductions in the range 13 to 17%. Details of modal split are contained in the table below.

Table 2 3 – Traffic leaving the western extension zone across all outbound roads. (Charging hours, 07:00 – 18:00, 2005 to 2007)


After the introduction of Congestion Charging in 2003, TfL expected a reduction in congestion of approximately 20 to 30%. A 2002 baseline value of 2.3 minutes  per kilometre was established.
Surveys of the Central London charging zone in 2003 indicated average delays  were about 1.6 minutes per kilometre - a reduction of 0.7 minutes per kilometre, compared with the 2002 baseline, a reduction of 30%. Subsequent years recorded a 30% (2004) and 22% (2005) reduction, compared with the 2002 pre-charging
baseline. During 2006 congestion reduction fell to 8%, while in 2007 congestion returned  to the levels experienced in 2002. This was not due to a rise in traffic levels,  which remain relatively unchanged. It is thought the increase was caused by  other factors, in particular a notable rise in the street works projects that  have affected capacity on the road network and thus traffic flow.

Public Transport network


Bus patronage figures for passengers entering Central London increased year on year between 1999 and 2002 – from approximately 70,000 passengers in 1999 to just below 88,000 passengers in 2002. There was a significant increase in 2003 to approximately 104,000 passengers, and a further rise to 116,000 in 2004. Patronage stabilised at around 116,000 in 2005 and 2006.

The Underground

The Underground has seen less of a significant impact on patronage since 2003. A recorded average of approximately 516,000 passengers exited stations in and around the central charging zone during the morning peak period in 2002. This rose to 523,000 in 2006 having been 498,000 in 2005.


The impact of the Charging Scheme on the environment is arguably best measured by changes in vehicle emissions and measured air quality. It is challenging to attribute the direct impact of the Charging Scheme on either in isolation.

There have been a number of factors, unrelated to Congestion Charging, which have had an impact on air quality, not least technology changes to vehicles and most recently the introduction of the London Low Emission Zone.

However, the improvement in air quality – reducing emissions to air – has been due in part to less traffic moving within central London and that which remains in the area moving more efficiently.

Table 2‑4 summarises the key percentage changes between 2002 and 2003 - before and after the introduction of the Congestion Charge in Central London.

Table 2 4 - Principal changes to emissions of NOX, PM10 and CO2 .


Former London Mayor Ken Livingston had proposed to introduce a higher daily levy - £25 (€30) compared to the current £8 (€9.60) charge – for high emission vehicles in the Autumn 2008. With the recent change in administration in May 2008 and new Mayor of London, Boris Johnson taking charge, this proposal has now been abandoned.

Table 2‑5 summarises the key the percentage changes to emissions inside the Western extension zone between 2006 and 2007.

Table 2 5 - Principal changes to emissions of NOX, PM10 and CO2 in relation to the western extension. Percentage change, 2007 compared with 2006. Annual average day, all road traffic emissions .

Source: Transport for London




The overall reduction in traffic crossing the congestion-charge cordon during the congestion-charge period (06.30–18.29 weekdays), was 22 % during the trial.1] This reduction was lower during the morning peak period (16%) and higher during the afternoon/evening peak (24%). The reduction stabilized quickly after the introduction of charges, and resettled at almost original levels as soon as the trial ended but not entirely (see figure below). During the permanent scheme from August 2007, traffic reductions have been almost as during the trial, but slightly lower. There are many ways for motorists to adapt in a situation with charges. During the trial approximately half of the disappearing motorists changed to public transport which increased by 6 %, and the other half changed in less traceable ways like fewer trips, trip chaining and other destinations. However, motorists did not increase car-pooling, work at home or change departure times.

A common assumption before the trial was that the time-differentiated charges would have significant impact on time-of-day choices, so that traffic volumes would increase during periods when passage was free of charge. Surprisingly enough, though, no such compensatory increases in traffic volume were observed for any time of day during the Stockholm trial. Rather, charging seemed to have a (small) reducing effect on traffic volumes over the cordon also after charging hours. This can be explained by the inherent linkage between trips over the day: The motorist, who does not take his /her car into the city in the morning, will not drive it out from the city in the evening, either. This effect must have outweighed the effect of substituting car trips between times of day.

The effect of charging is, naturally, at its largest just over the cordon. For all other types of streets, (inside the zone as well as outside) the effects were “diluted”. Only part of the car trips using those streets were subject to charges, and for other car trips no reduction should be expected1]. Therefore, the total reduction of vehicle kilometres traveled (VKT) within the charging zone, will be less than the reduction in number of passages over the cordon. Based on samples of link volumes, it was estimated during the trial that the effect on daily total VKT within the charging zone was approximately 14%, and that the corresponding figure for the region as a whole was 2%.

As a consequence of reduced demand, travel times are significantly reduced. These reductions are particularly large on the access (approach) roads to and from the inner City. Queuing times on these roads have fallen by one third for inbound traffic during the morning peak period (see next figure), and by half for outbound traffic during the afternoon/evening peak.

Also, travel time variability was reduced significantly in both AM and PM peaks. Travel time variability is known to constitute a major part of road users’ negative assessment of congested traffic conditions.

In the discussions before the trial, problems with redistribution of traffic was one of the main issues since it was decided to exclude a major motorway bypass through the city, from charging. This bypass – the Essinge link – was under severe congestion already before the trial. It was feared that through traffic that previously had used the inner city network would shift route to the Essinge link to avoid charges, and thereby further increase congestion problems there. Contrary to those expectations, however, volume increases on the Essinge link during the trial were very limited.

Air quality measurements are very sensitive to weather conditions, and do vary considerably from day-to-day and year-to-year. Therefore, the larger part of the environmental evaluation of the trial was model-generated. Emissions, concentrations and immissions (health effects) of a number of pollutants were computed for the situations before and during the trial, respectively. Real measured traffic volumes were used as input to the models.

The reduction in vehicle km during the trial, contributed basically proportionally to a reduction of the pollutant emissions from road traffic. Thus, such emissions were reduced for the region with 1%-3%, and for the inner city (charging area) with 8%-14%, see the following table. The reduction of Nitrogene oxides (NOx) were in the lower end of that range, as a consequence of additional bus traffic during the trial, which contributed to extra emissions.

Emission reductions were concentrated to the inner city, which is densely populated both day and night. Therefore, the relative effects on traffic related immissions and health problems in the Stockholm region were much larger than the effect on emissions. Based on recent estimates of dose-response relationships from several consistent international studies, it was estimated that in total for the entire Greater Stockholm area (1.44 million inhabitants, 35 x 35 km), between 25 and 30 fewer premature deaths would occur per year as a result of a reduction in long-term exposure to particles.

The congestion charging system managed to press average yearly concentrations of pollutants below what is required according to environmental quality standards (legally binding by European agreement). However, also when congestion charging is implemented, there are a number of locations in Stockholm at which maximum daily levels, as defined by European environmental quality standards, will remain to be exceeded.

1] In fact, there is reason to expect that non-charged trips may even have increased to some extent, as a consequence of reduced travel times. However, the evaluation program was not able to identify and/or quantify such rebound effects.

1]Depending on how you define the demand calculations from Stockholm show that the cost elasticity vary from - 0,27to - 0,41. Elasticities for different groups have not been estimated for Stockholm.


Concerning the effects of the Oslo packages on the network, Lian (2004) puts forward the following points;

  • A fully connected metro system and road lanes reserved for buses have been important and effective measures for public transport.
  • During the period 1990-2002 traffic growth has been slightly lower than the national average, in spite of strong growth in traditional drivers of mobility like population, employment and income. Thus, it is hard to claim that major road investments have induced new traffic in general in the region.
  • There is a slight reduction in travel times during morning rush hours, but no significant change in the afternoon. Increased road capacity has thus counterbalanced the growth in traffic with a small positive margin.
  • Delays vary by corridor, western and southern corridor being the worst. Road sections 10-15 km from the city centre have the largest delays. Freighters regard road accessibility to be improved.
  • Oslo Packages 1 and 2 are generally considered to be success stories (see “bullets” above), but many important transport projects will not be financed by 2008. Furthermore dismantling the Oslo Toll Ring is in the short term calculated to increase road traffic by 8-10 %. Expected traffic growth from 2001 to 2025 without the toll ring is around 30 %. Critical parts of the trunk road system (mainly some tunnels) may be overloaded by 2015. The Inner city is already considered to receive traffic flows near its capacity, in terms of road space and environmental conditions. This development may undermine the benefits of Oslo Package 1 and 2 resulting in increased and more unpredictable travel times and more traffic in residential areas and shopping streets.

One of the main reasons for the Oslo package was the local environmental problems caused by traffic and congestion in the late 80’s. On this aspect, Lian (2004) concludes that “Air pollution levels do not seem to be negatively affected by road investments. Noise nuisance is reduced where new roads are built as tunnels. Measures to improve local environment, like traffic management, reinforce environmental effects.” Overall, the effects of the Oslo packages on the local environment have been positive. This is not due to traffic reduction effects from the toll ring, but through the investments in road infrastructure. The investments have made the increase in traffic occur on the main roads rather than local roads.

Concerning global emissions, there has been a discussion to what degree improved road infrastructure induces more traffic. This may have adverse effects on the global emissions. Lian (2004) find no strong support for induced traffic from the packages.


No information available.

The Hague

To what extent participants behavior changes reduced overall congestion between Zoetermeer and The Hague is not (yet) clear. However, the changes themselves are described in the following figures.

A reduction of rush-hours car trips by about 50% was observed. This reduction was obtained mainly by rescheduling trips to earlier or later points in time. A shift to public transport occurred, but with a moderate percentage.

One special circumstance was the delay of public transport project RandstadRail. The original reason to schedule the trial during Autumn 2006 was the redesign of the local rail network between The Hague and Zoetermeer during Summer 2006. The plan was to convert the local heavy-rail loop into a light rail operation and to link it to the existing light rail system of The Hague. As the start of the trial approached, however, it became clear that construction planning had gone off track and that the trial would have to start with reduced rail operations (mainline rail only). A roughly scheduled bus replacement service continued to operate after the summer. However, this bus service was not sufficient to substitute the traditional local rail service: during rush-hours, in fact, there were always delays.

At this point, no environmental effects are known.


The introduction of the scheme achieved an 85% reduction in vehicular traffic (from over 2000 to approximately 200 vehicles per day).


  • Significant reduction in traffic levels and delays within the city centre.
  • An increase of 5% in total journeys terminating in the city centre by all modes.
  • A small reduction in overall traffic levels and delays between the inner and outer cordons, and only small changes outside the outer cordon.
  • Slight increase in orbital traffic between the cordons, with some localized changes that would require mitigation measures.
  • An increase in public transport use of around 10%.

The investment package would have had further impacts on achievement of transport strategy objectives. These include environmental improvement (for example through grants for clean engines in buses and taxis, and city centre environmental enhancement); social inclusion, through the substantial improvement to public transport; and safety and residential amenity (more funding for 20mph zones and safe routes to schools). It would provide the ability to maintain higher standards of safety and comfort for road, footway and cycleway users through increased maintenance funding.


During the period between January and December 2008 the number of vehicles entering the zone have been 1,382,946, of which 12% were commercial vehicles, 78.7% were occasional users (less than 10 accessing days out of 233 days) and 2.1% were systematic users (more than 50% of the 233 days).

The decrease in vehicles accessing the Ecopass Area was - 56.7% of Euro 0, Euro 1 and Euro 2 vehicles, while the number of Euro 3, Euro 4 and electric/hybrid vehicles increased by 5.5% on average. The traffic reduction, both private and commercial, within Ecopass area during the enforcement was 14.4% and 3.4% outside the zone.

By evaluating the available data and the results from modelling the vehicles reduction can be imputed to:

  • A 35% of change in route by charged vehicles for circulating without entering the Ecopass area;
  • A 17% of car fleet renewal with less polluting vehicles;
  • A 48% of modal shift with an increase of 5.7% of public transport patronage.

Effects on commercial speed of Public Transport

Another important result deals with the effects on the commercial speed of public transport. In fact the analysis on all the lines passing through the Ecopass Area between 7.30 a.m. and 7.30 p.m. of working days has shown that, in respect to a mean reference value metered before Ecopass implementation, the speed of public transport has increased by 6.7%.

Effects on modal shift

A first estimation of modal shift towards the metro lines has been carried out by ATM (Azienda Trasporti Milanesi) and shows that the number of outbound passengers at metro stations located inside the Ecopass Area has increased by 5.7%.

The table below shows the increase of passengers using the metro for travelling towards and within Ecopass area.

After one year since the Ecopass scheme has become effective the evaluation of traffic emissions before and after the implementation reveals that within Ecopass area there has been a reduction of total PM10 emissions from road traffic equal to 14%, 11% of NOx, 9% of CO2 and 37% of NH3 (ammonia).


No information available.


Since the IT system was installed, the number of accesses has reduced by 25% in the L.T.Z., by 3% in the three main streets of the city centre and by roughly 70% for unauthorised use of bus lanes. Moreover, thanks to the introduction of these new pricing initiatives, a reduction of 27% of freight operators permits and 10% of total permits (operators plus citizens) to access in the LTZ has been achieved.

Inside the LTZ there is another area called “T” (see in yellow in the figure below), very important for public transport; in this area the restriction are higher than in LTZ and also here the access is controlled by IT system.

In addition to access restriction for non authorised vehicles, the deployment of these IT systems has the following 2 key goals:

  • the improvement of Urban Public transport (UPT);
  • the introduction of pricing policies which will reduce existing access permissions as foreseen by the new Freight City delivery Plan.


No information available.

Dutch National Case

No information available.


No information available.


No information available.


Short Term Effects of the 1991 Scheme

The evaluations based on 1990 and 1992 travel survey data and traffic counts, concluded that over the week as a whole, there was a small decrease in total car traffic crossing the toll ring in the inbound direction. However, this decrease was smaller than the general reduction in car traffic in Trondheim during the same period. It should be noted that the early nineties was a recession period in the Norwegian economy. For a number of years there was no increase in car ownership, and in general zero growth in traffic on the roads.

Looking at time periods, inbound car traffic through the toll cordon decreased by 10% during both the high and low charged periods, and this decrease was almost offset by an 8-9 % increase in inbound car traffic during uncharged periods at evenings and at weekends. Thus, the toll ring caused a general shift in timing for car trips away from the charged hours, but the percentage reduction was not affected by the differentiation between peak and off-peak charges. 

The following table shows that for some trip purposes, adjustments were more substantial. The change in departure time was largest for home-based shopping trips, with a major increase in the number of trips outside the charged periods. Also for trips from work to home, the motorists adjusted their time of travel according to the charging system.

The travel surveys show that the number of CBD shopping trips increased in toll-free periods and decreased in tolled periods. No significant changes in destinations for shopping trips were detected. The travel surveys indicate a slight increase in the use of public transport and cycling. However, the toll ring effects are difficult to single out because of parallel improvements in public transport and in the bicycle road network. More car sharing was not detected as a response to the charging.

Measured Effects after Termination of Charging

When charging was discontinued at the end of 2005, the vehicle counting equipment at all stations was maintained in operation for at least three months. Automatic counting was kept running for six months at five stations, and for the whole of 2006 at only one of the closed stations. This enabled traffic changes between 2005, the last year with tolling, and 2006, the first year without tolling, to be studied hour by hour and day by day. 

A result for typical local traffic is shown in figure below for three stations located along the main bypass road. Whilst traffic in the formerly charged periods increased by 11.5 %, traffic for the whole week increased by only 3.8 %, and traffic at working day evenings and at weekends decreased. The total increase for working days constituted 7.5 %.

Looking at percentage of traffic within charged hours for working days, this increased to 76.5 % in 2006 from 73.9 % in 2005. This shows that motorists that were priced out during charging periods have returned back to the more preferred periods for making trips.

The following figure provides evidence that some drivers in 2005 started early to avoid being charged; traffic in 2006 between 05:00 and 06:00 decreased by 11 % whilst traffic between 06:00 and 07:00 increased by 11 %. In the afternoon, shifts in departure times to avoid being charged are even more evident; the last of the charged hours, between 17:00 and 18:00, has a 20 % increase in 2006, and an 8 % decrease in the following hour.

Finally, the next figure shows that increases in volumes for working days were largest in the afternoon, smaller during the middle of the day and smallest in the morning. This pattern may at first glance seem surprising, considering that charges were higher in the morning hours 06-10 than later in the day.

The explanation for this has to a large degree to do with how trip purposes are distributed in time during an average working day. Work, school and business trips are fairly inelastic with respect to departure time compared to other trip purposes. The split between these two groups of purposes are depicted for time intervals in the figure below, for the same origin-destination segment as in the previous figure. For the part of the day that was charged during 2005, there is clearly a negative correlation between the shift in volumes in time periods and the share of work, school and business trips in the same time periods. The larger are the share of other trips, the larger are the changes in volumes. This indicates that the progressively larger increases throughout the day can be explained by a corresponding larger share of private trip purposes, having a larger elasticity of demand with respect to the choice of departure time.

Traffic entering the city from the east is affected by the fact that the Ranheim toll plaza is still in operation. This is a bi-directional charging station in operation 24 hours a day and 7 days a week with the purpose of providing revenues for the E6 East motorway project. When the municipal charging stations were demolished, motorists in 2006 were able to make detours using routes that were now free of charge, to avoid passing through Ranheim. The result was considerable increases between 2005 and 2006 at places like Skovgård (48 % for charged periods and 25 % for average daily traffic) and Tunga (20 % for charged periods and 16 % for average daily traffic), and corresponding decreases at Ranheim (-17 % for charged periods and – 11 % for average daily traffic).

Some of the stations that came into operation close to the city centre during the last expansion of the charging system were also affected by route change adjustments. Considerable increases in traffic levels at these stations in 2006 indicate that motorists returned back to preferred routes which they had been priced out from using.

On the whole, traffic in the formerly charged periods Monday to Friday 06:00 to 18:00 increased much more than traffic during other periods of the week between 2005 and 2006. For most parts of the municipality, traffic increases for the week as a whole was in line with the general traffic growth in the county. For the southern part of the municipality, it can be argued that the annulment of charging lead to traffic increases that were higher than otherwise expected.

There has been no comprehensive study to evaluate the environmental effects of the Trondheim tolling schemes. A measuring station collecting data on PM10 dust particleswas in operation in one of the heavily trafficked main approach roads to the city centre since 1993 for the extended winter season (Oct/Nov – May/June). Due to the widespread use of studded tires and the weather conditions in the winter time, this period is the most interesting period to look at for air pollution effects. Dry and cold weather tends to bring the concentrations up to high levels.

Based on observations of PM10 levels, it is not possible to conclude that the toll ring had an effect on air quality. The variation in concentration is most likely a result of changing weather conditions.