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Dr Muriel Beser Hugosson,
Project manager of the evaluation programme at the Stockholm Congestion Charge
Secretariat, Transek AB
Dr Jonas Eliasson,
Chairman of the Expert Group, Transek AB
The Expert Group consists of eight traffic experts with various specialities. The group
read all documentation and then, during three intensive full-day seminars, drew the
conclusions presented in this summary of the evaluation of the Stockholm Trial.
Several group members have in different ways participated in preparatory tasks prior
to the evaluation and also conducted follow-up activities during the course of the trial.
The Expert Group is chaired by Dr Jonas Eliasson, Transek AB and its secretary is
Dr Lena Smidfeldt Rosqvist, Trivector Traffic AB. Other members are Associate Prof.
Staffan Algers, Royal Institute of Technology/Transek, Dr Karin Brundell-Freij
Engineering Faculty, Lund University, Managing Director of Inregia AB Cecilia
Henriksson, Inregia AB, Prof. Lars Hultkrantz, Örebro University and scientific advisor
to the Swedish Road and Transport Research Institute., Managing Director of
Trivector Traffic AB Christer Ljungberg and Dr Lena Nerhagen, Swedish National
Road and Transport Research Institute
©Association for European Transport and contributors 2006
On 2 June 2003, the Stockholm City Council adopted a majority proposal to conduct
congestion charges trials. The formal decision on implementation was made through
the Riksdag (Swedish Parliament) passing the Congestion Charges Act on 16 June
The trials started on 22 August 2005 with extended public transport. On 3 January
2006 the trial implementation of congestion charging started. The trials were
concluded by 31 July 2006. The trials were evaluated continuously from a number of
different perspectives. This evaluation was summarized in a report in early summer
2006. A referendum on the permanent implementation of congestion charges will be
held in conjunction with the general election on 17 September 2006.
The primary objectives of the trials are to reduce congestion, increase accessibility
and improve the environment. The purpose of the (full-scale) trials is to test whether
the efficiency of the traffic system can be enhanced by congestion charges.
Secondary objectives of the trials
• Reduce traffic volumes on the busiest roads by 10-15%
• Improve the flow of traffic on streets and roads
• Reduce emissions of pollutants harmful to human health and of carbon dioxide
• Improve the urban environment as perceived by Stockholm residents
• Provide more resources for public transport
The Stockholm trials consist of three parts; extended public transport, extended parkand-ride facilities and the congestion charge.
The public transport was extended with 197 new buses and 16 new bus lines. This
provides an effective and fast alternative for travelling at peak hours from the
municipalities surrounding Stockholm into the inner city. Where possible existing bus, underground- and commuter train lines were reinforced with additional departures.
To facilitate travelling 2800 new park-and-ride facilities were built in the region. The
total number of parking spaces is 13800.The already existing park-and-ride facilities
was also made more attractive.
During the trial period owners of vehicles registered in Sweden were required to pay
the congestion tax if their vehicle passed a control point on the way in or out of the
Stockholm inner city area on weekdays between 6.30 a.m. and 6.29 p.m.
©Association for European Transport and contributors 2006
Figure 1. The 18 control points located at Stockholm city entrance and exits
There were 18 control points located at Stockholm city entrances and exits. Vehicles
were registered automatically by cameras that photographed the number plates.
Those vehicles equipped with an electronic onboard unit for direct debit payment
were also identified through this means. The traffic flow was not affected as drivers
were not required to stop or slow down when driving past a control point. Vehicles
were registered when driving both into and out of the inner city zone.
The cost for passing a control point was SEK 10, 15 or 20 depending on the time of
day. See the table below. The maximum amount was charged during the peak hours
between 7.30 and 8.29 a.m. and 4 and 5.29 p.m. The maximum amount payable per
vehicle and day was SEK 60. No congestion tax levied in the evenings or at night nor
on Saturdays, Sundays, public holidays or the day before a public holiday. The
maximum charge was SEK 60 per day and vehicle.
Figure 3. The cost for passing a control point was SEK 10, 15 or 20 depending on the time of day.
©Association for European Transport and contributors 2006
Some vehicles were exempted from the congestion tax: emergency vehicles, buses
with a total weight of at least 14 tonnes, diplomatic cars, taxis, motorcycles, vehicles
registered abroad, military vehicles, alternatively fuelled cars, vehicles used by
people with a disabled persons parking sticker.
There was no congestion tax levied on vehicles driving on the E4/E20 (Essingeleden)
past Stockholm. Neither was there any congestion tax for vehicles driving from
Lidingö (an island eastern of Stockholm) if they passed the bridge control point and
they subsequently passed another control point to exit the inner city zone within 30
minutes. The reason behind this exception is that the only land connection from
Lidingö Municipality runs through the city.
All costs were paid by the national government. The budget for the trials is SEK 3,8
To be able to evaluate the Stockholm trials a large effort was made on an evaluation
plan [1]. This plan was initiated in cooperation with the Swedish Road Administration,
the Stockholm County Council regional planning and traffic unit, Stockholm Transport
(SL), various research institutes, certain City of Stockholm administrative offices and
experts from other bodies, organizations and companies.
The objectives of the evaluation plan was to
• Ensure that the evaluation highlights relevant aspects of the congestion
charges trial,
• Fulfil stringent demands for quality of scientific method and factual content,
• Ensure that the results of the evaluation have a high degree of validity and can
be used for research and development in the field.
The evaluation was divided into three different levels. The first level was a
comprehensive evaluation, consisting of more than 30 different evaluation projects.
This first level was designed as a comparison between before (spring and autumn
2005) and during (spring 2006) periods. The second level was the monthly indicators
– some selected indicators to monitor changes over time. The third level was the go
live evaluation – this level showed effects directly after introduction of the congestion
tax it made it possible to meet the need of information from media.
The comprehensive evaluation consisted of a large number of different evaluation
tasks such as travelling patterns (Stockholm county travel survey), road traffic, effects
on public transport, pedestrian and bicycling traffic, parking, road safety, air quality,
noise, trade, cost benefit analysis, regional economy, Stockholm citizens’ experience
of the urban environment, distribution hauling, impact for taxis and courier services,
attitudes towards congestion taxes etc.
The studies cover a large number of fields, including not only travel habits and their
effect on vehicle traffic and public transport but also travelling patterns (Stockholm
county travel survey), pedestrian and bicycling traffic, parking, road safety, air quality,
noise, trade, cost benefit analysis, regional economy, Stockholm citizens’ experience
of the urban environment, distribution hauling, impact for taxis and courier services,
attitudes towards congestion taxes etc.
©Association for European Transport and contributors 2006
Many of the effects of the Stockholm Trial are strongly dependent on external factors,
for example economic trends in the Stockholm region and Sweden as a whole. As a
result, the evaluation also includes studies of the retail market and the general
economic situation. Between monitoring periods before and during the Stockholm
Trial there were external factors that influenced effects monitored in the various
studies. The most important factors were that petrol prices went up and the Södra
Länken bypass tunnel was opened.
A comprehensive follow-up and evaluation of the effects of a project the size of the
Stockholm Trial is a difficult task which has not been made easier by the short time
available to conduct the follow-ups. Regarding methods, there are numerous factors
that are difficult to handle. Of these, we have already mentioned the influence of
external factors on effects. Several of the studies took the form of panel studies, i.e.
the same persons were questioned about their behaviour prior and during the
Stockholm Trial. These panel studies have many advantages but also call for caution
when drawing conclusions since there was an age disparity between monitoring prior
to and during the trial.
The results presented in this paper are the summery of all effects based on the
evaluation projects that the expert group presented in June 2006 [2].
Vehicle traffic declined more than expected
Traffic goals of the congestion tax were that the number of vehicles passing over the
charge cordon during the morning and afternoon/evening peak periods should
decline by 10-15% and that accessibility should improve on Stockholm roads with the
heaviest traffic. The congestion tax was designed to meet these goals but
uncertainties regarding the effects of the tax, as earlier mentioned, were many.
Numerous monitoring, of various types, were conducted and analysed to produce
information on traffic changes.
The main features of the traffic reductions are crystal clear. The Stockholm Trial cut
traffic flows - more than expected, in fact - the decline being surprisingly stable,
taking into account normal seasonal variations during spring. In addition, the effects
of the trial were seen further out from the charge zone than we initially expected traffic volumes declined at locations far from the charge cordon. Consequently, many
of the feared side-effects - on link roads at the city’s outskirts, for example - were
unfounded. The decline in traffic volumes was measured via traffic monitoring but has
been demonstrated in special studies as well.
Exactly as expected, the biggest traffic decline was in vehicles passing over the
charge cordon, which includes all approaches to the inner city. For an entire day’s
charge period (24 h), the decline was about 22%, equivalent to 100,000 passages
over the charge cordon.
The decline in vehicles passing over the charge cordon was biggest during the
morning and afternoon/evening peak periods. The biggest decline of all was during
the afternoon/evening peak period, which can be probably be partly explained by the
fact that during the afternoon/evening travel is not dictated to the same extent by
time/destination as in the morning peak period’s journeys to work. Traffic also
declined during evenings after the charge period. The reason may be fewer
©Association for European Transport and contributors 2006
outward/return journeys by car during the charge period, resulting in fewer return
journeys during evenings after the charge period. We hope to provide a better
explanation in August in connection with our updated analysis, in which we will
analyse the major travel-habits survey.
The traffic decline on the southeast approach road was bigger than the average
decline for the entire charge zone. The decline to/from Lidingö, on the other hand,
was less than the average. This was expected, since traffic to/from Lidingö that
passes through the charge zone within a 30-minute period is not subject to the
congestion tax. Regarding the fact that the traffic decline is bigger from
south/southeast, it is conceivable that the reason is that the percentage of through
traffic is higher and consequently more drivers can choose to drive round the inner
city to avoid the congestion tax. Hopefully, the travel-habits survey will provide a
more detailed explanation.
Traffic flows on big inner-city streets during the charge period declined but not as
much as over the charge cordon. This is natural since the traffic flow in the inner city
also includes vehicles belonging to people who live there, etc., who do not leave the
charge zone but use their vehicles for transport within the zone. There are also signs
from studies other than traffic monitoring that motorists who do not need to pass over
the charge cordon benefit from the decline in congestion and, in fact, now use their
cars more often. This could partly explain why the traffic-flow decline in the inner city
is lower.
©Association for European Transport and contributors 2006
-26 %
-6 000 fordon
-22 %
-19 000 fordon
-21 %
-28 000 fordon
0 f
on -19 %
-12 000 fordon
Figure 4.Change in traffic flows over charge cordon during charge period (6.30 a.m.-6.30 p.m.) per
direction. ("Fordon" means vehicles in Swedish)
Fears of collapse on Essingeleden (E4/E20) and other bypass routes were
unfounded. Differences everywhere are small if compared to normal week-by-week
Traffic in Södra Länken (bypass tunnel) has continually increased since it opened in
October 2004. It is impossible to determine to what degree the increase in 2006 is
due to the congestion tax. Normally, new infrastructural developments have a long
“running-in” period and, in addition, the large number of people moving to Hammarby
Sjöstad (a new housing district in the southern part of Stockholm) has certainly led to
traffic increases. These effects, together with an accident causing lane closures on
Essingeleden in October 2005 (a floating crane collided with one of the bridges),
influenced both traffic volumes and the reliability of traffic monitoring. We have taken
account of this in our evaluation.
The only approach that deviates from the pattern of shorter travel times is
Värmdövägen (from Nacka Centrum, western of Stockholm city, to the entrance to
Södra Länken). The increased traffic in Södra Länken also causes longer queues on
Värmdövägen westwards in the morning peak period. Travel times, however, are
significantly shorter than previously after this point, i.e. the continuation of
Värmdövägen-Stadsgården westwards in towards the city. There is a similar trend on
Nynäsvägen (south of Stockholm city).
©Association for European Transport and contributors 2006
According to manual monitoring of approach-road traffic, the number of commercial
vehicles passing the charge cordon has also declined. The manner in which
commercial drivers have changed their travel habits is, however, uncertain.
Figure 5. Change in traffic volumes (weekdays, 24-hour period), April 2005 compared to April 2006.
Congestion rose at the end of April in line with the annual spring increase in traffic
and it has been discussed whether this was due to the effects of the congestion tax
declining over time. It is true that congestion has increased but it is the result of a
normal seasonal increase in traffic. The effects of the traffic decline are, however, the
same in a month-by-month comparison with earlier years. A probable contributing
factor to the increase in congestion - in addition to the increase in traffic - is that the
number of cyclists and pedestrians also went up with the arrival of spring. They also
utilize traffic-system capacity. Another interesting reflection is that if the traffic decline
is equally large during the entire period, taking account of the first half-year’s
seasonal variations, it means that additional vehicle journeys made during the spring
were just as much affected by the congestion tax as those made when the Stockholm
Trial began during the winter.
Accessibility improved
A consequence of vehicle traffic declining is that accessibility improved and travel
times fell. This had a large, positive influence on the reliability of travel times, i.e.
travellers were now more certain that a journey could be made within a given period.
Travel times for vehicle traffic declined significantly in and near the inner city.
Particularly large declines were seen on approach roads, on which queue times fell
by one-third during the morning peak period and by one-half during the
afternoon/evening peak period. This is an important improvement for car commuters
to/from the inner city since it means that travel times are shorter and more reliable.
When high congestion occurs, disparities in travel times on the same stretch with
different traffic conditions - which can vary from day to day - are very big.
©Association for European Transport and contributors 2006
Figure 6. Change in travel times (morning peak period), April 2005 compared to April 2006. Inner city
enlarged (right).
The relatively high congestion on Essingeleden means that travel times vary greatly
from week to week, even if traffic volumes are generally unchanged. In the light of the
traffic increases we can see on Essingeleden, it is reasonable to believe that travel
times have increased. However, in the monitoring done between 2005 and 2006 no
increase in travel times can be seen.
Traffic increases in Södra Länken lengthened travel times there compared to 2005.
With available data, it is impossible to say how much of the traffic increase is due to
the congestion tax and how much is the result of a traffic increase that would have
occurred irrespective of the congestion tax. We can, however, say with certainty that
there is great deal here that is not the result of the Stockholm Trial.
It is clear that the decline in traffic volumes and improved accessibility has led to a
better work environment for commercial drivers, seen in varying measure in all
studies with commercial drivers - bus drivers, taxi drivers, couriers and trades people
- conducted before and during the Stockholm Trial.
Traffic declines result in less damage to the environment and better health
Vehicle exhaust emissions constitute a large part of the total amount of pollution in a
city. Released into the air, emissions mix with other pollutants and thus affect air
quality. Different pollution or exhaust-emission substances have various types of
effect. Sometimes it is the level of pollution - numerous emissions mixed in the air where people are that is most significant and sometimes it is the total amount of
emissions. Regarding carbon-dioxide emissions, which are important for the
greenhouse effect, it is the total amount of emissions that is decisive. Air quality,
mainly measured by particle levels, affects the health of people in a city, resulting in
increased heart, vascular and lung diseases as well as increased discomfort for
sensitive groups (asthmatics and people with other bronchial disorders as well as
those suffering from heart and lung diseases).
Total exhaust emissions caused by vehicles is due to both total vehicle kilometres
travelled - i.e. the total of distances covered - and exhaust-emission factors, i.e.
emission of different substances that each vehicle emits per driven kilometre.
Total kilometres travelled multiplied by emission factors results in total amount of
exhaust emissions (expressed in, for example, tons/year) for different substances.
©Association for European Transport and contributors 2006
Emission factors are influenced by vehicle-park composition and how vehicles are
driven. For example, a driving style with many speed variations produces more
emissions than one with a more uniform speed. These relationships are complicated
and it is therefore difficult on the basis of input data to exactly calculate the result of
the Stockholm Trial in the form of reduced emissions. Emission calculations carried
out were done on the basis of various emission models which differ in regard to
which factors are taken in account when making the calculation. However, calculation
results are similar. Assumptions made in the calculations probably mean that, in any
case, effects have not been exaggerated. The calculations primarily show that a
decline in traffic volumes leads to reduced emissions but also that it is changes in
vehicle-park composition that are decisive as regards how much the emission of
particles/nitric oxides falls.
The Stockholm Trial led to reduced emissions of both carbon dioxide and particles.
The reduction of carbon dioxide is approximately proportionate to the decline in
vehicle kilometres travelled, which means that the effect of traffic on exhaust
emissions dropped by 2-3% in Stockholm County and about 14% in the inner city. As
the result of one measure - the Stockholm Trial - this is a major reduction even if the
decline in Stockholm County can only be seen as an interim step if the aim is to meet
national climate goals. Carbon dioxide emissions are the traffic emissions most
difficult to reduce.
The total decrease in the amount of particle emissions is similar to that for traffic
volumes but for these substances the most significant factor is where the reductions
take place since they contribute to local pollution levels. The Stockholm Trial has led
to an approximate decrease in the effect of traffic on pollution levels by one-twentieth
for the County of Stockholm and one-tenth for the inner city. According to the
Stockholm County Council, reduced use of studded tyres is an important step in
meeting the environmental quality standard for particles. In the case of Hornsgatan in
Stockholm’s Söder district, a 10% fall in the use of studded tyres would result in a
reduction of pollution to levels equivalent to the decrease that the City of Stockholm’s
Environmental Office calculated that the congestion tax would produce. However, the
fact is that the congestion tax, in addition to reducing particle counts (measured in
PM10) at street level, even leads to a reduction in the level of smaller exhaust
particles, which is also a benefit to health - a benefit that cannot be gained by
reducing the use of studded tyres.
There are also environmental quality standards for nitrogen dioxide, NO2. The NO2
count at street level is decided not only by vehicle emissions but even by factors such
as the occurrence of other substances. Vehicle emissions of nitric oxides (NOx - not
only NO2) have declined continually during recent years due to stricter vehicleexhaust regulations. The effect of this decline on NO2 counts at street level in
Stockholm’s inner city is, however, much lower. This is the result of the complexity of,
for example, chemical reactions. Thus, it cannot be expected that the congestion tax
will be of any great significance in meeting NO2 environmental quality standards.
Exposure to particles affects the population’s health and mortality rate. Calculations
based on the connection of congestion-tax effects to early mortality due to exposure
to air pollution show that traffic reductions resulting from the Stockholm Trial save
about five otherwise “lost” years. That is also the expected reduction used in the costbenefit calculation for the Stockholm Trial. New research results, presented in an
evaluation report, indicate a significantly higher saving. Calculations based on the
©Association for European Transport and contributors 2006
new research results point to the avoidance of about 25-30 early deaths, equivalent
to about 300 years.
Bearing in mind that there is thus an obvious risk that health effects may be larger
than what has traditionally been expected, one should not ignore the importance of
reduced exposure. To get the best result from a measure aimed at reducing exhaust
emissions, activities should be focused on areas where population density is highest
and, consequently, many people are exposed to emissions affecting their health. Via
the congestion tax, emissions can be controlled according to where the tax is levied.
Consequently, the effects of the congestion tax have a larger influence on health per
given emission amount than a petrol-tax increase. The emission reduction in the
inner city resulting from the congestion tax has, for Stockholm County as a whole, a
health effect that is about three times as big as the health effect that would have
resulted from a decline deriving from a rise in petrol prices evenly distributed
throughout the county.
As expected, the Stockholm Trial in general has led to only small changes in noise
levels since large traffic-flow changes are necessary to perceive an
increase/decrease of noise levels.
Anything less than 3 dBA will not be perceived as a difference in noise levels which,
as regards traffic, is equivalent to about a doubling or halving of traffic volumes.
Calculations of noise-level changes due to the Stockholm Trial reveal changes of 1
dBA or, at most, 2 dBA for average levels over a 24-hour period. There are,
therefore, an extremely small number of locations where changes in noise levels can
be perceived. However, even minor noise-level changes of 1 dBA mean that the part
of the population that feel disturbed by traffic noise declines. Perception of noise
levels can also improve if one experiences less congestion and vehicle traffic. In the
city-environment study there are results indicating that people believe there is less
noise now in spite of the fact that, in principle, it is impossible to perceive the small
noise reductions that have taken place.
Noise continues to be a big problem in Stockholm, as in many other places in
Europe, and is now the subject of a special EU directive. One goal is to create quiet
zones, which puts large demands on traffic reductions. It is difficult to see how such
traffic reductions could be achieved without very effective steering measures to limit
vehicle traffic.
Public transport important part of the Stockholm Trial
Accessibility for bus traffic to/from and in the inner city has increased. Since inner-city
timetables were not adjusted for the trial period, improved accessibility has not
significantly shortened travel times for inner-city buses. Punctuality has probably
improved and as regards bus traffic passing over the charge cordon travel times have
shortened considerably.
Efforts to improve public transport (park-and-ride sites, expanded bus and light rapidtransit train services) did not, on the basis of current documentation, yield any visible
effect on the total number of public-transport journeys during autumn 2005 - before
the start of the Stockholm Trial. That is not say there is no such effect, just that, if it
exists, it is too small to register in SL’s passenger statistics or in the travel-habits
survey conducted in autumn 2005. It is indeed improbable that the public-transport
expansion would not have any effects on the total number of public-transport
©Association for European Transport and contributors 2006
journeys but adequately detailed analyses and statistics enabling such an increase to
be identified are not yet available. SL’s onboard surveys on the new buses indicate
that it has enticed motorists to switch to public transport but their number is still too
small to make an impression when considering total public-transport travel. Totally,
travel with SL was about 2% higher in autumn 2005 compared to autumn 2004 but
that increase is believed to be due to higher petrol prices.
Public-transport travel was about 6% higher in spring 2006 than in spring 2005. The
congestion tax seems to have increased public-transport travel by about 4.5%, while
higher petrol prices and other external factors are probably responsible for the rest of
the increase (about 1.5%). Congestion on public transport (measured by the number
of standing passengers) increased somewhat on the Underground and decreased on
commuter trains. Overall, congestion seems to be unchanged, probably partly due to
expanded public transport.
Another question is if the congestion tax would, in fact, have reduced vehicle traffic
even if public transport had not been expanded. Expanded public transport, as
mentioned above, has as yet certainly not provided any evidence of an increase the
number of public-transport journeys,1 but it is quite conceivable that it boosted the
effect of the congestion tax by making the switch from car to public transport easier. If
that is the case, part of the effects of the congestion tax should instead be registered
as an effect of expanded public transport.
Still, we believe that that effect, even if it exists, must be small. We base this belief on
the fact that onboard surveys on the new buses show that, between autumn 2005
and spring 2006, the number of new passengers who earlier used their cars for
transport was tiny compared to the reduction in the number of passages over the
charge cordon. Of the vehicle-traffic reduction of 22% over the charge cordon, at the
most 0.1% can be ascribed to expanded bus traffic.
Problems with commuter-train traffic during the winter seem to have led to reduced
travel on these services. It is unclear which alternative mode of transport passengers
chose. Some have certainly used other public-transport alternatives or refrained from
travelling while others have instead used their cars. Commuter-train problems should
therefore, to a certain degree, have limited the traffic reduction resulting from the
congestion tax.
Road safety improved as a result of reduced traffic
Road-safety effects are, without exception, difficult to evaluate and the short period of
the Stockholm Trial makes it hard - not say impossible - to draw conclusions on the
basis of follow-ups of actual and reported accidents during the trial. Evaluations of
the road-safety effects of the trial are therefore based on estimates and the
connection between road safety and changes in traffic volumes, traffic flows and
speed levels.
Research shows that road safety is mainly influenced by changes in traffic volumes
and speed levels. Since traffic declined as a result of the Stockholm Trial that means
that even the estimated number of accidents within the charge zone in which people
were injured is lower. The size of the reduction in accidents is, of course, uncertain
but based on model estimates the number of accidents where people were injured
should have fallen by about 9-18%. Reduced congestion should also have led to
higher speeds, resulting in an expected increase in the number of accidents where
©Association for European Transport and contributors 2006
people were injured. This effect, however, is not as big as the effect of traffic
The total effect of the Stockholm Trial on road safety is undoubtedly judged to be
positive since the positive effects of the traffic reduction are expected to be bigger
than the negative effects caused by higher speeds. A large number of road accidents
within the charge zone occur during the charge period. A cautious estimate is that the
Stockholm Trial has led to a reduction in the number of accidents within the charge
zone where people were injured by 5-10%. Converted to yearly values, this would
equal an annual reduction of between 40 and 70 accidents in which people were
injured. This can be seen in the light of the fact that, on average, 2,155 people are
injured and 23 people die in road accidents per year in Stockholm County.
The majority of those who are injured, both in the county and inner city, are motorists.
In the inner city, just over a third of those injured are unprotected road users.
Difficult to judge whether Stockholm citizens think the city environment has
The city environment is complex and diffuse concept. It is difficult to find a common,
clear-cut definition of what is meant by a “good” or “improved” city environment. It is
also difficult to measure these types of effect. Since a perceived improvement in the
city environment is one of the goals of the Stockholm Trial we have, in spite of
documentation that is hard to analyse, tried to make an evaluation. To draw
conclusions from the study carried out is made difficult not only by the abovementioned general problems but also by the completely different weather conditions
during the two monitoring periods. Our conclusions are therefore very cautious.
The result points to perceived improvements of exactly those factors for which
measured changes can be demonstrated, i.e. those connected to traffic reductions.
In the city environment study, citizens feel there is an improvement in traffic tempo,
air quality and vehicle accessibility. The same tendency is seen in interviews with
cyclists in the inner city and children living in the inner city. Inner-city children’s
perception of the city environment has very clearly improved and many cyclists think
there are fewer cars in the inner city and that the traffic environment has got better.
Perception of things that have got worse mainly concerns accessibility - by foot and
cycle and on public transport. The result does not support any clear-cut or
unequivocal appraisal of whether the city environment in general has improved.
Perceptions of accessibility by foot or cycle are strongly influenced by the weather
and season and monitoring took place at different periods. However, the conclusion
is that effects clearly associated with traffic changes can be seen in how the city
environment is perceived.
Many ways of adjusting to the new situation
If the congestion tax is introduced permanently, there will be both short- and longterm adaptations. Because the Stockholm Trial is just a trial – and a short one at that
– one can only expect short-term adaptations. This is all we have measured and all
we can evaluate. In the long term, there will also be localization effects, discussed in
the section about the effects on the regional economy. There are even possible longterm effects at an individual level. For example, it may be, in a slightly longer
perspective, that part-time workers will reorganize their work time to reduce the
number of journeys subject to the congestion tax.
©Association for European Transport and contributors 2006
There is a wealth of different strategies for adjusting to the new situation created by
the Stockholm Trial. We have searched the evaluation material for anything
sufficiently of note to show up in monitoring and test results. At an individual level,
there are even more variations than the ones we comment on. It is important, in the
meantime, to remember that in discussions about the different adjustment strategies,
only a small portion of county citizens’ journeys are affected by the congestion tax.
Prior to the Stockholm Trial, county citizens made about 300,000 vehicle journeys per
day over the charge cordon during the charge period. This is equivalent to 14% of all
car passages and 7% of all passages during one work day in the county. Most of
these journeys were work-related.
There are two different types of adaptations which point in two different directions.
One is to adapt in order to avoid the congestion tax one way or another, which
reduces traffic. The other is to utilize the lack of congestion which is the result of the
reduction in traffic, which counteracts the reduction in traffic. A further adjustment to
avoid the congestion tax is to use a clean car which – not unimportantly – reduces
damage to the environment. Increased use of clean cars does not, however, reduce
It is very clear that vehicle traffic has fallen, especially in the inner city. Not only
private motorists but also commercial traffic seems to have adjusted travel habits.
According to manual calculations of approach-road traffic over the charge cordon, car
traffic has been reduced by 30 %, light trucks by 21 % and trucks by 13 %.
There is much uncertainty over how many of car journeys have instead been
replaced by travel on public transport. According to SL, some 40,000-50,000 new
trips are being made with public transport. If this is so, it is not even half the number
of car journeys no longer being made over the charge cordon. Hopefully, analysis of
SL’s measurements and the summer’s survey of travel habits in Stockholm County
will provide a clearer picture of what has occurred. The new park-and-ride sites
introduced for the Stockholm Trial have largely been filled, but it is not clear if this is
the result of the congestion tax or the result of a need which has now been met. The
increase in park-and-ride sites (approximately 2,000 cars per day) is almost
insignificant, however, in relation to the number of vehicles passing over the charge
cordon (about 530,000 passages per 24-hour period prior to the introduction of the
congestion tax) or to the reduction in traffic (about 100,000 fewer passages per 24hour period). Each individual vehicle can make several journeys.
Several of the results from the evaluation imply that some motorists have changed
the time at which they travel. This is, however, not the only adjustment to journeys,
as some studies of adjustment of travel times prior to the Stockholm Trial showed.
Journeys have more likely been reorganized to become fewer or more efficient and
also changed to include other means of transport.
Calculations of the average number of passengers per car also show that shared
travel has not increased to any measurable degree. The average number is stable at
1.27 people per car.
Because public transport, pedestrians and cyclists have not collectively increased as
much as vehicle traffic has decreased, this must mean that some travel has simply
“disappeared”, especially as cycling has, moreover, decreased in the monitored
periods. The adjusting mechanisms remaining as explanation for what has happened
with car journeys are that people have chosen other routes or closer destinations,
©Association for European Transport and contributors 2006
that people have coordinated errands so they can be achieved with fewer trips and
that some trips are simply not being made.
Despite the fact that approximately half the vehicle journeys over the charge cordon
which have “disappeared” are now being made by public transport, it is interesting to
note that the “amount of travel” in the previous situation is not a static fixed number
which can be replaced, but that there is a large adjustment potential in simply
reducing travel in different ways. The early result of surveys of travel habits seems to
point to a reduction in the frequency of travel – people are not making as many trips
as they did prior to the introduction of the congestion tax. A reduced frequency of
vehicle journeys over the charge cordon can even be seen in the study of commuter
trips from the Stockholm/Malaria region to Stockholm’s inner city and in the study on
attitudes, where people now say they make fewer trips to the inner city. Even large
changes in heavy traffic (seen in the manual calculations of approach-road traffic)
support the reasoning and explanations of route planning and information given by
transport companies.
Adjustments in the form of taking advantage of reduced congestion on roads are
seen, for example, in the study of work travel to/from two large workplaces. Among
these commuters, there are now several who don’t need to cross the charge cordon
and who now travel in peak-period traffic. Among these commuters who live and
work outside the charge cordon, the percentage choosing a car as transport has
increased somewhat. Further examples of this are that because there is a smaller
traffic reduction in the inner city than over the charge cordon, people now choose
Klarastrandsleden, because it is now possible to travel there without hinder. There
are, therefore, many people who do not pay, but who are still able to take advantage
of improved accessibility.
People have become more positive as they have experienced the effects
We have not yet had access to the complete analysis of the attitude survey
presented in the summer. Conclusions are based on the “monthly indicators”,
excerpts from result tables from the attitude survey as well as studies of company
It is clear that both the public and companies have become increasingly positive
towards the congestion tax and the Stockholm Trial, as they have gained their own
experience and as benefits have begun to appear. This is normally what the
acceptance of change looks like: Without individual experience, people see almost
exclusively barriers and costs, but with individual experience they begin to discover
the advantages and benefits gained for these costs. There is, however, a lot of
uncertainty over how fast these changes in attitude take place.
The percentage of Stockholm County citizens who think there is a problem with
congestion has fallen compared to the period prior to the introduction of the
congestion tax. Even attitudes to the Stockholm Trial have become more positive
during this time. In autumn 2005, about 55% of all county citizens believed that it was
a “rather/very bad decision” to conduct the congestion-tax trial. Since the congestion
tax was introduced in January 2006, this percentage has continuously fallen. In April
and May 2006, 53% believed that it was a “rather/very good decision” while 41%
believed that it was a “rather/very bad decision”. Significantly, even those travelling
by car to/from the inner city during the charge period in the most recent two 24-hour
periods have become more positive by several percentage units.
©Association for European Transport and contributors 2006
As with the general population, companies have moved from being primarily negative
to more positive, both to the Stockholm Trial and to the congestion tax as a
permanent measure. The shift is more apparent for the trail itself than for the
congestion tax as a permanent measure.
Companies are, as far as we can tell, united in their criticism of the inconvenience
and the administrative costs the congestion tax bears in its current form. There is
even evidence that companies still believe that the system is hindering growth, but
while there were opinions before the Stockholm Trial that both the individual
company and other companies would be affected negatively, opinions are now more
moderate regarding the individual company’s negative development.
In attitude surveys, it is clear that the reason for choosing to drive a vehicle compared
to before the Stockholm Trial is now increasingly that it is possible to save time
compared to other means of travel. There has been a decline among those who
choose public transport due to too much traffic and queuing. This is interesting,
because it means that improvements in accessibility which can be measured
objectively have also been visible “to the naked eye”.
It also appears that people using public transport are very satisfied with the direct
Motorists with company cars are a group where it is harder to judge the adaptations
made. This is because the actual cost of the congestion tax for private travel is
sometimes paid for by the employer, sometimes by the employee. There is also an
in-between variant, where the employee pays via a gross-salary deduction, which
means that the actual cost of the congestion tax is significantly reduced. We do not
have a clear picture of how the different variants have been applied during the
Stockholm Trial. In the study of two workplaces, it was clear that Swedish Postal
Service employees will eventually be debited for congestion-tax charges for private
It is reasonable to say that company-car motorists pay less, on average, to pass the
charge cordon than private motorists. We also expect company-car motorists to be
less price-sensitive because of their on-average higher incomes. Manual calculation
of approach-road traffic also shows an increased percentage of company-car
motorists passing over the charge cordon.
The technical system works
We would have liked an assessment of how the technical system has worked.
Because we do not currently have this kind of evaluation we can only make an
overall estimation. We know that we cannot assess how complicated the congestiontax system is for each individual and/or organization at an overall level.
We can, however, conclude that on an average day in May 2006, 371,300 journeys
took place over the charge cordon, resulting in 115,100 tax decisions and income of
more than SEK 3 million. Of these 115,100 tax decisions, 100 were investigated by
the Swedish Tax Agency and five were appealed. The Swedish Road Administration
customer-service unit received on an average day in May 2,200 calls, as opposed to
an expected 30,000 calls. Based on this, our assessment is that the system generally
worked well. The case studies carried out imply the system needs adjustment to
reduce inconvenient administration for companies.
©Association for European Transport and contributors 2006
There is reason to note that red-tape costs for both individuals and companies are
now absent from cost-benefit evaluations. It is probable that many experienced the
initial inconvenience as high but that it has fallen as people have learned how
payments can be made in the simplest way.
Benefits and costs distributed differently
Results of the travel-habits survey and analysis of distribution effects for various
group affiliations are not yet available. This section will therefore be supplemented in
August with an analysis.
Based on the first evaluation of the expansion of public transport in the autumn of
2005, it was, as expected, mainly people of middle income who changed from car to
public transport, as well as people with children and people born overseas. It is
normally primarily people of middle income who change, which can be explained by
the fact that people of low income already use public transport and that the incentive
for people of high income to reduce their car travel is not as strong.
The main “winners” of the congestion tax are:
• Public-transport travellers who get a better choice.
• Those who drive cars without passing the charge cordon and therefore have
shorter travel times at no extra cost.
• Cyclists who appear to have a better traffic environment.
• People who value their time highly and think that more time is worth money.
• Commercial drivers who gain a better work environment (bus drivers, taxi
drivers, truck drivers, etc.).
The main “losers” are:
• Those who drive a car over the charge cordon and for various reasons cannot
adapt their travel and who don’t think more time is worth money.
• Those who are “forced off” the roads.
• Public-transport passengers who experience more public-transport
Marginal effect on regional economy
The regional economy may be affected both in the short and the long term. The
effects on the economy depend to a large degree on whether – and in what way –
the congestion tax is returned to the region. The effects of the Stockholm Trial on the
economy have been investigated in several different studies. Most important, an
overall economic analysis of the trade outlook and trade developments has been
carried out in the county. Moreover, studies of the retail market, visitor-intensive
activities, handicraft companies, driving schools, rubbish hauling, delivery traffic,
taxis, transportation for the sick and handicapped and courier firms are also included.
It is clear that the economy is dependent on a functioning road-transport system.
The short-term effect on the retail market and other sectors studied shows only small
average effects. The effects often disappear among other factors which have more
influence, for example new retail shops. Revenue measurements carried out show
that the Stockholm Trial has had small influence on the region’s retail market. The
©Association for European Transport and contributors 2006
durables survey in shopping centres, malls and department stores during the
Stockholm Trial period shows that these have developed at the same rate as the rest
of the country. Street-level durables sales have fallen, but the time series is too short
to be able to draw conclusions (partly because VAT reporting for small companies is
a long way behind).
The basis on which we judge long-term effects on companies is how companies
themselves expect to act.
Earlier experience, including that from London, implies that the congestion tax results
in small effects compared with the regional economy as a whole. Normal variations in
the economy are generally larger than the per year effects of the congestion tax. The
Stockholm Trial’s contribution to total production in Stockholm County was 1 of SEK
750 billion. The congestion tax has in most cases only a marginal effect on a
company’s total transport costs. For households, the congestion tax has, according to
the Stockholm Trial model, an effect of about one per thousand of total disposable
income per year. This means that purchasing power in the county has not been
significantly affected, but for individual households the tax can have tangible
Model calculations of the changed attractiveness of different areas are very sensitive
to the value of time – pounds and pennies for what time is considered to be worth,
what is assumed. The analysis shows many small changes that are uncertain
because of this sensitivity to which assumptions are made. The changes are also
small in comparison with generally increased pressure from a growing number of
citizens and workplaces in the region. Even the influence on house prices is not of
great significance. The long-term effects according to the model are not greater than
the normal price variations between two quarters.
Cost-benefit analysis shows the congestion tax is profitable
A cost-benefit analysis is a means of systematically trying to summarize the effects
and costs of a particular measure. The analysis is carried out to establish whether a
measure is “worth the money”, in other words whether the value it creates is greater
than its cost.
The Stockholm Trial – regarded as a short trial which, after completion, is not
assumed to be repeated – creates a cost-benefit loss of about SEK 2.6 billion.
Investment in and operation of the congestion-tax system makes up the greater part
of the loss. This does not take into account the value of knowledge and research.
This perspective is of limited interest; that the investment in the congestion-tax
system was not recouped during the trial period is not a surprise.
Making the congestion-tax system permanent is calculated to yield a significant
annual cost-benefit surplus of about SEK 760 million (after deducting operating
costs). It would take four years to pay back the congestion-tax system’s investment
costs in the form of social-economic benefits. This is a very short payback time
compared, for example, with road or public-transport investments which, in
favourable scenarios, have a payback time in terms of cost-benefits of 15-25 years.
From a cost-benefit perspective, the most relevant basis for a decision is really to
ignore the cost of the investment – the Stockholm Trial cannot be undone and the
investment made cannot be recouped. But the congestion tax is still cost-benefit
positive, even when the cost of the investment is taken into account.
©Association for European Transport and contributors 2006
The cost-benefit surplus of the congestion tax is found, for example, in shorter travel
times (worth SEK 600 million per year), increased road safety (SEK 125 million per
year); and health and environmental effects (SEK 90 million per year). Revenues
from the congestion tax are calculated at SEK 550 million per year (after the system’s
operation costs have been deducted).
Increased bus traffic is considered unprofitable from a cost-benefit perspective, both
during the Stockholm Trial and if it was made permanent. Benefits are calculated to
reach SEK 180 million per year, compared to a cost-benefit operational cost of SEK
340 million per year. The result should be treated carefully, however, because it is
not unusual for public transport to be considered unprofitable according to a costbenefit analysis in strict terms, while still being considered worth operating for
different reasons.
Environmental effects in terms of road safety, climate and health are worth somewhat
more than what the congestion tax costs road users via various types of sacrifice.
Valuing and estimation of both road safety and the environment is subject to
uncertainties. This uncertainty is obviously not desirable, but neither does it play a
significant role in the total cost-benefit evaluation of the project.
The cost-benefit analysis looks at the average effects on all individuals in the
community. For particular individuals, the consequences of the congestion tax can be
both positive and negative. The net effect for different individuals depends to a large
degree on how the income generated from the system is used.
Based on older research into the health effects of traffic, the congestion tax appears
above all to be an accessibility measure and improved accessibility is where the big
cost-benefit values lie. Health effects are small compared to the value of increased
accessibility when using the somewhat older relation between emissions and health.
If you instead use the latest research on the effect of traffic on health, the congestiontax health effect increases. The total value of the environmental and safety
improvements would almost double.
Large effects compared to other measures
That vehicle traffic decreases as driving becomes more expensive is hardly
surprising. An interesting question, however, is how great the effect of the Stockholm
Trial is compared to other types of measures. The answer is that the reduction in
traffic congestion and travel times is big compared to other measures which have
been carried out or discussed in regard to Stockholm traffic. The following can be
mentioned as examples:
• A new eastern connection between Nacka and the inner city (the so-called
Österleden or Eastern bypass) is estimated to reduce the number of vehicles
passing over inner-city bridges by approximately 14%. The equivalent reduction
for a new Western bypass (bypassing the City of Stockholm) is estimated at 11%.
• The rise in the price of petrol by just under 1 SEK (9%) which took place between
April 2005 and April 2006 is estimated to have reduced traffic over the charge
cordon by less than 3%.
©Association for European Transport and contributors 2006
• The zero tax on Stockholm’s public transport is estimated to reduce vehicle
kilometres travelled – the total of distances covered – in Stockholm County by 3
It should also be remembered that road investments are expensive and roads take a
long time to build. Many desirable investments in Stockholm fall into the severalbillion-kronor class. For example, the Stockholm Bypass is estimated to cost SEK 20
billion and the Citybanan (a commuter-train tunnel) about SEK14 billion. Since the
congestion tax instead results in a surplus of SEK 500-600 million each year, after
operational costs have been deducted, it is unreasonable to set these investments
against the congestion tax, as if they were comparable substitutes for each other.
Both financially and from a traffic perspective, it is more natural to see them as
At the same time, it should be pointed out that the congestion tax – even if the net
effect for society is positive – does mean sacrifices for many people. These sacrifices
should be set against the positive accessibility and environmental effects that the
congestion tax leads to.
The significance of the Stockholm Trial as such
The Stockholm Trial resulted in a unique collection of data about traffic and its effects
in Stockholm. Knowledge and competence in this area therefore increased. We
briefly present some of these lessons:
For example, we can now see that improvements in travel times are so tangible that
they have been perceived by the general public, which has also expressed
satisfaction with this improvement. A valuable lesson of the Stockholm Trial is also
that travel-time improvements occurred far from the inner city. This was not
previously known.
The 10% reduction in truck passages over the charge cordon was unexpected. For
the future, it would have been valuable to be able to discuss in more detail what the
commercial-traffic adjustments actually look like
Many of us – though not all – were surprised that no more than about half of the
motorists who “disappeared” were replaced by travellers using public transport
instead. This is a sign that the number of trips is not a fixed number which can be
divided into different destinations, modes of transport or times. Even though
adjustment in travel-start times was seen in several studies, the substantially reduced
number of vehicle journeys makes it clear that this adjustment strategy is of lesser
significance. A further factor supporting this is the fact that Essingeleden has coped
so well.
Adjustment to the congestion tax occurred and it took place quickly. Before the
Stockholm Trial – and especially when it became clear that the trial period would be
reduced to six months – there was some doubt as to whether the traffic reduction
would actually take place. Would the trial be considered as something so brief and
transient that it wasn’t worth changing behaviour, with people deciding instead to ‘sit
out’ the trial period without adjusting travel habits? We now know that the Stockholm
Trial had an immediate effect.
Since there is no direct effect to be seen on the retail market and the rest of the
economy, the Stockholm Trial has revealed the possibility of reducing travel without
influencing economic growth, so-called decoupling.
©Association for European Transport and contributors 2006
The Stockholm Trial provides interesting insights into what a road-toll system should
look like – something which is also useful for other cities. Traffic economists have
long discussed to what extent a charge-zone toll of the kind used in Stockholm is
sufficient for controlling traffic in an entire city. Traffic relations change from street to
street and from minute to minute. When the charge zone is as large as it is in
Stockholm, there was concern that even if it had a big effect on travel over the charge
cordon, streets inside the zone would soon be full of motorists already in the zone
increasing travel as they realized the streets were less congested. Alternative
solutions were discussed for several years prior to the Stockholm Trial, involving
several sub-zones with varying rates of the congestion tax. None of the existing
road-toll systems threw much light on this question. In London, it is a question of a
small area in the city centre, in Singapore access to cars is also regulated and in
Oslo and Bergen the system is designed to affect traffic as little as possible. The
Stockholm Trial confirms that a simple charge-zone toll creates significant effects
within a large area.
Prior to the possibility of the congestion tax becoming permanent, there is reason to
discuss how the tax should be structured and differentiated. We believe, for example,
that the charge period should be shortened somewhat in the mornings. There may
also be reasons to consider whether tax levels should vary in relation to seasonal
traffic variations. We have no definite answer to the question of whether it is desirable
from a traffic perspective to make an exception of Essingeleden. Even though
accessibility has not significantly worsened during the Stockholm Trial period,
increased traffic on this bypass means increased vulnerability to disturbances of the
traffic system as a whole.
It is also clear that increased investment in public transport cannot alone be used as
a means of reducing congestion. Investment in public transport does not appear to
result in any measurable increase in public-transport travel or reduction in vehicle
traffic, despite SL registering increased travel on its network. A well-functioning
public-transport system is a prerequisite, however, for being able to manage the
increasing number of public-transport passengers.
What can be changed if the congestion tax becomes permanent?
The structure of the system is influenced by what the main goals are – it is of great
significance whether the primary aim is to reduce congestion or to reduce the effect
of traffic on the environment. In the event of the congestion tax becoming permanent,
goals for what is to be achieved in the short and long term should be carefully
discussed and formulated. From a cost-benefit perspective, the congestion tax
should primarily be treated as an instrument for dealing with congestion.
• The relatively simple congestion-tax structure with a charge cordon has not led to
dramatic differences in goal achievement at different locations. Know-how is now
available, however, that can be used if a more complex congestion-tax structure
is introduced. From a traffic perspective, it would be desirable to be able to vary
congestion-tax levels throughout the year. Traffic in May-June is significantly
higher than in winter and then falls to a very low level in the summer. This means
that the traffic reduction necessary for good accessibility varies throughout the
year. This could be steered by varying congestion-tax levels throughout the year.
©Association for European Transport and contributors 2006
©Association for European Transport and contributors 2006
• The goal of a 10-15% reduction in traffic flow is probably at the lower end of what
needs to be achieved for good accessibility at certain times and places. In MayJune, when traffic is at its height, greater reductions than this are necessary to
achieve really good accessibility.
• The total congestion-tax level, on the whole, has been adequate, or possibly more
than adequate, to achieve desired effects.
• It is difficult to give any definite answer to the question of whether the congestion
tax should be levied on Essingeleden traffic when the inner city is already subject
to congestion tax. To date, accessibility has been relatively unchanged compared
to last year but the traffic load is so high that accessibility is greatly affected even
by small changes in traffic flow.
Congestion taxes can make Stockholm more attractive
For many cities, attractiveness is an important question for future development and
survival. It has been said that the congestion tax negatively influences attractiveness
but it is worth noting that serious congestion problems make it more difficult for
businesses to operate, which reduces a city’s attractiveness.
In many larger cities around the world, congestion and environmental influences
hinder continued sustainable city development. Congestion taxes are now discussed
in a large number of European cities and many are closely watching developments in
Stockholm. In the USA, it was recently decided at federal level to carry out a large
number of trials using congestion taxes. In all these cases, the congestion tax is seen
not only as a means of increasing accessibility but also as a means for cities to retain
their attractiveness and develop for the benefit of citizens and business. As an
example, it can be mentioned that Kathryn Wylde, president of a business
association in New York called Partnership for New York City, said at the
international conference “Voices on the Stockholm Trial” that business in New York
believes a congestion tax is necessary for the city to continue to be attractive in a
way that makes it possible for businesses to continue to develop.
Recent research shows that a city’s attractiveness is of great importance when
seeking skilled personnel, who in turn attract companies and create growth. Seen in
this perspective, the Stockholm Trial and a permanent congestion-tax system would
increase Stockholm’s attractiveness.
[1] Evaluation programme Stockholm Trials, City of Stockholm, February 2006.
[2] Facts and results from the Stockholm Trials, City of Stockholm, June 2006.

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