SUSTAINABLE TRANSPORTATION

Abstract

This paper discusses possible contributions of psychologists to sustainable transportation. It is argued that in order to reach sustainable transportation, among others, behaviour changes of individual car users are needed. As transport policies will be more effective if they target important antecedents of travel behaviour, first, factors influencing such behaviour are discussed. It is argued that car use is very attractive and sometimes even necessary for many different reasons. This implies that a combination of policies is called for, each targeting different factors that support car use and hinder the use of more sustainable modes of transport. Next, the paper elaborates on policy strategies that may be employed to achieve sustainable transportation by changing car use. Increasing the attractiveness of sustainable transport modes by means of pull measures seems not sufficient to reduce the level of car use. Besides, car use should be made less attractive by means of push measures to force drivers to reconsider their travel behaviour. The acceptability of such policies may be increased by clearly communicating the aim of these policies, and the expected positive consequences (e.g., less congestion, improved environmental quality). Moreover, possible negative effects for individual freedom may be compensated by implementing additional policies aimed at facilitating the use of sustainable transport modes.

Full text

IATSS RESEARCH Vol.31 No.2, 2007 1
SUSTAINABLE TRANSPORTATION* – A Psychological Perspective – L. STEG
SUSTAINABLE TRANSPORTATION*
– A Psychological Perspective –
Linda STEG
Department of Psychology
University of Groningen
Groningen, the Netherlands
(Received December 18, 2006)
This paper discusses possible contributions of psychologists to sustainable transportation. It is argued that in order to reach
sustainable transportation, among others, behaviour changes of individual car users are needed. As transport policies will be more
effective if they target important antecedents of travel behaviour, first, factors influencing such behaviour are discussed. It is argued
that car use is very attractive and sometimes even necessary for many different reasons. This implies that a combination of policies is
called for, each targeting different factors that support car use and hinder the use of more sustainable modes of transport. Next, the
paper elaborates on policy strategies that may be employed to achieve sustainable transportation by changing car use. It was con-
cluded that increasing the attractiveness of sustainable transport modes by means of pull measures is not sufficient to reduce the
level of car use. Besides, car use should be made less attractive by means of push measures to force drivers to reconsider their
travel behaviour. The acceptability of such policies may be increased by clearly communicating the aim of these policies, and the ex-
pected positive consequences (e.g., less congestion, improved environmental quality). Moreover, possible negative effects for indi-
vidual freedom may be compensated by implementing additional policies aimed at facilitating the use of sustainable transport
modes.
Key Words: Sustainable transportation, Travel behaviour, Car use, Psychology, Motivations, Behaviour change
1. SUSTAINABLE TRANSPORTATION:
A PSYCHOLOGICAL PERSPECTIVE
It is widely acknowledged that the current transpor-
tation system is not sustainable1. The increasing use of
private cars has generated various environmental, social
and economic problems. Emissions of toxic and harmful
substances contribute to global warming, local air pollu-
tion (e.g., emissions of particles in urban areas), and
smog, thereby threatening ecosystems and human health2.
Moreover, car use threatens urban quality of life, e.g., be-
cause it is noisy and yields traffic accidents3,4. Further-
more, the accessibility of economic important destinations
is endangered.
Technological solutions aimed to reduce the nega-
tive impact per car and per kilometre driven (e.g., energy-
efficient cars) do not appear to sufficiently reduce these
problems of car use, so as to make it compatible with sus-
tainability1. The mitigating effects of new technologies
tend to be overshadowed by the continuing growth of car
use, and by the increase in the number of heavier cars that
are less energy efficient (such as SUV’s). Moreover, driv-
ers might be tempted to use their energy-efficient cars
more often because they are cheaper on fuel and more
environmentally friendly, a phenomenon known as the
rebound effect5 or the Jevons principle1. Therefore, behav-
iour changes of individual car users are needed as well.
Various types of behaviour change may help to
achieve sustainable transportation6. First, people may
adopt more energy-efficient driving styles (e.g., drive at
steady speed, shifting gears early). Second, people may
change their car use, i.e., combine trips, use different (i.
e., shorter) routes, change the time of travel to avoid traf-
fic jams, visit other destinations to reduce travel distance,
suppress certain car trips, or travel with other modes of
transport, such as public transport, cycling, walking or
carpooling. Third, people may replace their car by an en-
ergy efficient car or dispose of their car. Fourth, people
may move residence, or look for another job location to
reduce travel needs and distances.
Psychologists can contribute to sustainable trans-
portation by studying how such behaviour changes may
* The Japanese version of this paper was included in IATSS Review
(Vol.31, No.4, March 2007), the official publication of IATSS issued in
Japanese on a quarterly basis.

TRANSPORTATION
2 IATSS RESEARCH Vol.31 No.2, 2007
be achieved. Two questions need to be addressed. First,
we need to understand which factors cause travel behav-
iour. After all, policy strategies will be more effective if
they target important antecedents of behaviour. Second,
we need to examine which policies may be effective in
promoting sustainable transportation. More specifically,
we need to understand which policies may be effective,
acceptable and feasible to change travel behaviour. In
this paper, both questions will be addressed. We do not
aim to provide an extensive overview on these topics.
Rather, we summarise some of the main issues involved.
Section 2 discusses factors that influence car use. Section
3 elaborates on policy strategies that may be employed to
achieve sustainable transportation by changing car use.
The final section summarises the main conclusions.
2. FACTORS INFLUENCING CAR USE
Why do so many people drive their car? This ques-
tion has been addressed in many studies. This section re-
views important societal and psychological factors that
promote the use of a private car.
2.1 Societal factors
Car use has been stimulated by various societal
developments7,8. For example, reliable motor vehicles
and the corresponding infrastructure of roads, petrol sta-
tions, traffic regulation and the like became widely avail-
able. Increases in spending capacity have led more and
more people to own and use cars. Urban sprawl has in-
creased the need to travel. In many countries around the
world, infrastructural and societal organisation is tuned
towards the wide-spread availability and the regular use
of cars9. These (and other) developments have made the
use of private cars attractive and is some cases even nec-
essary8. Indeed, many people claim they need a car in
order to undertake their daily activities. But people also
presume the availability of a car when making choices on
where to live, work, shop, or how to spend their leisure
time. As a consequence, many people became dependent
of their car10,11; car use turned into a socio-economic ne-
cessity.
2.2 Psychological factors
Many studies revealed that people like driving. In
general, the car is much more attractive than other modes
of transport, particularly compared to travelling on public
transport. The car outperforms public transport in many
respects, e.g., the car is more convenient, flexible, com-
fortable, fast, independent, reliable and pleasurable than
public transport12-15. Especially travelling by bus is eval-
uated rather negatively16. Judgements about walking and
cycling are generally more positive16,17. However, these
modes of transport are feasible only for short distances.
2.2.1 Symbolic and affective motives for car use
What makes car use far more attractive than other
modes of transport? For a long time, studies focused on
the instrumental benefits of car use18. Also, transport pol-
icies typically target such instrumental factors, for ex-
ample by increasing prices of car use (e.g., tolls, parking
fees) or reducing accessibility (e.g., prohibiting cars from
entering certain areas). In most cases, such policies have
not resulted in significant changes in car use, suggesting
that other factors influence the level of car use as well.
Recently, it has been acknowledged that the private
car is not only very attractive because of its functional
properties, such as its speed, flexibility and convenience.
Besides, other motives seem to play an important role,
such as feelings of sensation, power, superiority, arousal
and pleasure18-20. Such symbolic and affective aspects
are emphasised in many car advertisements, e.g., pictures
of cars in spectacular landscapes. Moreover, the way
people talk about their car illustrates that for many, the
car is a symbol for status and success and a way to ex-
press yourself (e.g., people may talk about a ‘typical
BMW driver’). Based on this, it has been argued that car
use fulfils three different functions21: an instrumental
(i.e., it enables activities), a symbolic (i.e., the car is a
means to express yourself or your social position) and an
affective function (i.e., driving is pleasurable and arous-
ing). A study by Steg21 revealed that commuter car use in
the Netherlands is especially related to symbolic and af-
fective motives, and hardly to instrumental aspects. This
implies that differences in car use are especially related
to the extent to which people evaluate symbolic and af-
fective aspects positively, and not to the evaluation of in-
strumental aspects. Symbolic and affective motives may
even play a more important role when considering mode
choice for types of trips that are less functional, such as
recreational trips. Some authors argued that driving may
be desired for its own sake (and not be derived demand
only), as it emerges from the fact that people take their
car for a spin without having any goal to drive to22.
Symbolic and affective motives seem to be especially
valued by young and male drivers21. Thus, people do not
only drive because they need to do so, but also because
they love to do so. This may be one of the reasons why
attempts to change car use have not been very successful,
and it might explain the vast resistance against (effective)

IATSS RESEARCH Vol.31 No.2, 2007 3
SUSTAINABLE TRANSPORTATION* – A Psychological Perspective – L. STEG
policies aimed at changing or reducing car use. This im-
plies that policies should not only target the instrumental
costs and benefits of car use, but also its symbolic and
affective qualities.
2.2.2 Habits
Another process that strengthens the increasing use
of cars is the formation of habits. When behaviour has
positive consequences over and over again, habits are
formed. As car use has many advantages over other modes
of transport, it is very likely to turn into a habit. Indeed,
various studies revealed that car use is to a large extent
habitual23-25. When habits are formed, behaviour is guid-
ed by automated cognitive processes, rather than being
preceded by elaborate decision processes. That is, people
will no longer make conscious decisions, but use the
same mode again and again without even thinking about
it25. Habits may be even generalised across situations.
For example, a person who has a habit to commute by car
may use the car for many other trips as well, without con-
sidering whether this is indeed the best way to travel26.
Habits are highly functional to cope with daily life.
People do not have the cognitive capacity nor the time to
think through every single choice they make. Fortunately,
it is not necessary to make conscious decisions on how to
act time and again, since in many cases the choice cir-
cumstances will not be changed, and a person would have
come to the same decision anyway. However, habits may
not always yield optimal outcomes. In some case the cir-
cumstances may have changed. For example, a new bus
route may have become available which makes the bus
highly attractive compared to the car. Such changes will
generally not be noticed when habits are formed. Habits
result in selective attention: people tend to focus their at-
tention on information that confirms their choices, and
tend to neglect information that is not in line with their
behaviour. As a result, people know little about the
qualities (such as travel time and costs) of the modes of
transport they hardly use27. Habits may also result in
misperceptions, e.g., people tend to overestimate the
costs of travelling by public transport, while costs of car
use are underestimated. This is partly due to the fact that
people overlook fixed car costs, such as insurance and
maintenance costs.
In general, habits are reconsidered only when the
choice situation has changed significantly. Indeed, Fujii
and colleagues found that regulations that temporarily
forced car users to use alternative travel modes induced
lasting changes in car use 24,28. The impacts of such
temporary changes were particularly strong for habitual
car users who had little or no previous experience of us-
ing other travel modes, suggesting that these habitual
drivers had inaccurate perceptions about the pros and
cons of these modes.
2.2.3 Car use as a commons dilemma
The societal and individual factors discussed above
have made car use very attractive to many people. As in-
dicated in the Introduction section, car use has also vari-
ous negative consequences, among which environmental
and safety problems, and those associated with reduced
livability and accessibility of cities. These problems are
acknowledged by car drivers as well 8. This implies that
individuals perceive a conflict between the individual
benefits of car use and the collective problems caused by
car travel. This conflict between individual and collective
interests may be typified as a commons dilemma. A com-
mons dilemma is a situation of conflict between aggre-
gate collective interests and numerous individual interests.
In pursuing their own personal interests, individuals tend
to shift the (mostly limited) negative impact of their be-
haviour onto their common environment. The cumulative
effect of these numerous small impacts may result in seri-
ous deterioration of collective (environmental) qualities.
In a commons dilemma, people are tempted to act in their
own interests, especially because individual contributions
to the problems and their solution seem futile. Moreover,
some problems are uncertain, and only visible in the long
term (e.g., global warming). In contrast, acting in one’s
own interests yields certain positive outcomes in the short
term. For most people, the many advantages of car use
outweigh the negative consequences. Consequently, peo-
ple do not restrict their car use. However, people do not
always act in their own interest. Some use their car as
little as possible to safeguard collective qualities, even
though this might be less comfortable for them. Indeed,
car use appears to be correlated to environmental consid-
erations, i.e., high environmental concern, high aware-
ness of problems of car use, and strong ecological norms
are associated with less car use, although correlations are
typically not strong8,29-31.
3. CHANGING CAR USE
The previous section revealed that many factors
have made car use very attractive. The car outperforms
other modes of transport, most particularly public trans-
port, in many different respects. Consequently, many fac-
tors could and should be targeted in order to successfully
change car use and to reach sustainable transportation.

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4 IATSS RESEARCH Vol.31 No.2, 2007
We indicated that car use is influenced by individual mo-
tivations and perceptions as well as by the situational
context. This implies that car use may be changed by
changing individual motivations and perceptions, or by
changing the context in which decisions are made. The
former may be referred to as psychological strategies,
while the latter may be labelled as structural strategies for
behaviour change.
3.1 Psychological strategies
Psychological strategies are aimed at changing in-
dividual perceptions, beliefs, attitudes, values and norms.
Information may be provided to heighten people’s aware-
ness of the problems of car use, to increase people’s knowl-
edge about possible alternatives for driving, or about the
behaviour of others. The underlying assumption is that
people behave in a reasoned way and that behaviour can
be modified by altering the perceived costs and benefits
associated with particular choices. However, this assump-
tion is not invariably true. First, feasible alternatives
should be available before providing information can
have any effect. Second, information provision is not
very effective when habits are formed. In that case, peo-
ple may not reconsider their initial choices or not even
notice the information because of selective attention.
Third, in some cases information may be counter effec-
tive. For example, a study by Tertoolen and colleagues32
revealed that information about the negative environmen-
tal effects of car use resulted in a reduction of the aware-
ness of environmental consequences of car use. Apparently,
in this study, car users experienced a discrepancy between
their environmental attitude and their actual behaviour.
Such a discrepancy causes an unpleasant psychological
tension, a phenomenon called cognitive dissonance. Peo-
ple are motivated to reduce this tension. The easiest way
to do so is changing their attitudes (rather than their be-
haviour). However, information proved to be quite effec-
tive in some cases. Most notably, individualised social
marketing approaches, in which information is tailored to
the needs, wants and perceived barriers of individual seg-
ments of consumers, have resulted in significant changes
in car use33. Another important reason for the success of
such approaches is the use of various techniques for
catching attention to the offerings33. The provision of in-
formation is an important prerequisite for implementing
other, more stringent measures as well. Public support for
such measures may be increased by informing people
about the need for and possible consequences of such
measures.
3.2 Structural strategies
Structural strategies are aimed at changing the rela-
tive attractiveness or feasibility of behavioural options by
changing the external context. The assumption is that be-
haviour is strongly influenced by the context in which
decisions are made. In the long term, attitudes and prefer-
ences may change as well, in line with the behaviour.
Three types of structural strategies may be distin-
guished: financial measures, legal regulations and physi-
cal changes. Financial measures are aimed at changing
the prices of behavioural options. Car use can be made
more expensive (e.g., by increasing or introducing car
taxes, tolls, kilometre charges) or the use of (sustainable)
transport modes may be made cheaper (e.g., subsidising
public transport, tax discounts). The basic assumption
underlying this strategy is that prices steer behaviour, and
that people will choose the option with the highest utility
against lowest costs. However, this is not always the
case34. First, feasible alternatives to car use should be
available. Second, financial considerations are not the
main determinant of car use. Many other considerations
may play a more important role, such as comfort, speed,
and flexibility, and people may be prepared to pay for
these qualities. Third, if habits are formed, small price
increases may not be notified. Fourth, people may not be
well-informed about prices of different modes of trans-
port. As argued earlier, people generally underestimate
costs of car use, suggesting that significant price increas-
es are needed before people reconsider their car use.
Legal regulations may be effective as far as laws
and regulations are internalised by those affected. How-
ever, people may resist, or elude, the laws and regula-
tions. If they do so on a large scale, legislation will be
discredited and the practical effect of it will be virtually
nil. Effective regulation and enforcement are crucially
dependent on majority public support, or at least compli-
ance. Legal regulations require adequate organisation for
supervision, monitoring and enforcement. On the posi-
tive side, applying a regulation and enforcement strategy
may help to increase people’s trust in the cooperation of
others, as far as there is a guarantee that one’s own will-
ingness to comply is not exploited by others, viz., that
others will adapt their behaviour to the laws and regula-
tions as well35.
Physical changes are directed at changing urban
form and available technical apparatus. Traffic can be di-
rected via certain routes, geographical relationships be-
tween destinations may be changed, and technological
innovations may be introduced. The underlying assump-
tion behind such measures is that behaviour is shaped by

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SUSTAINABLE TRANSPORTATION* – A Psychological Perspective – L. STEG
the circumstances. However, individual preferences may
be opposed to such changes, e.g., people may not want to
live in compact cities with mixed land use that would re-
duce their need to travel. Moreover, urban planning is
typically effective in the long term only; current land use
patterns shape the possibilities for exhaustive geographi-
cal reorganisations. Technological innovations aimed at
making cars more energy-efficient (and thus less pollut-
ing) are very important to reduce emissions. Unfortu-
nately, such solutions tend not to be sufficient to manage
the problems of car use, because their effects tend to be
overtaken by the continuing growth of car use. Techno-
logical solutions also may not solve the problems of car
use completely: for example, energy-efficient cars may
help control environmental problems, but will hardly
solve accessibility problems36. Drivers might even be
tempted to use their energy-efficient car more often be-
cause it is cheaper and more environmentally friendly
(the rebound effect; see Introduction section). Moreover,
technological innovations may have unwanted effects.
For example, the more people favour technological solu-
tions, the less they are willing to reduce car use and the
more they reject policies aimed at this objective32. Also,
some technological innovations are not easily imple-
mented. For example, the introduction of electric or hy-
drogen cars requires a widespread adaptation or expansion
of the infrastructure needed to keep them in service.
3.3 Push and pull measures
Structural strategies may be aimed at making car
use less attractive or feasible via so-called push measures
(i.e., ‘penalties’), while the use of more sustainable trans-
port modes may be stimulated by means of pull measures
(i.e., ‘rewards’)37. Table 1 lists important merits and de-
merits of push and pull measures. Push measures are
more likely to restrict people’s freedom of choice, while
pull measures typically increase the (quality of) available
behavioural alternatives. Geller38 argued that pull mea-
sures are generally more effective in changing behaviour,
because in case of rewards, behaviour changes are associ-
ated with positive affect, feelings and attitudes, increas-
ing the probability that the desired behaviour will become
a social norm. In contrast, penalties may be accompanied
with negative affect and attitudes, and may threaten indi-
vidual freedom, which may result in behaviour contrary
to compliance with a mandate39. However, pull measures
will be effective only when they succeed in making car
use less attractive than more sustainable choices. Given
the many advantages of car use, this will not be easy to
accomplish. In this vein, it has been argued that pull mea-
sures are generally less effective in changing car use be-
cause they are likely to fail to make car use less attractive.
Moreover, they are less successful in activating goals to
change car use and to facilitate the implementation of
such goals40. Indeed, in the transport domain, push mea-
sures have been more successful than pull measures. For
example, increasing prices of car use (e.g., by introduc-
ing tolls) was effective in reducing car use in some cities
(such as Singapore, London), whereas decreasing prices
of bus use did increase bus ridership, but did not result in
reductions in car use6. However, push measures are gen-
erally not easily implemented because of lack of public
support. Public support may increase if people believe
policies will be effective in reducing the problems caused
by car use, and if the policies do not seriously threaten
individual freedom of choice. Moreover, policies are
more acceptable when policies are believed to be fair and
when people trust the good intentions of the government
implementing the policies6.
3.4 Factors influencing the effectiveness of rewards
and penalties
Three factors affect the effectiveness of rewards
and penalties. First, the most powerful motivating conse-
quences are “certain” and “soon”38. This increases the
likelihood that people associate the reward or penalties
with their previous behaviour, which in turn increases the
salience of the reinforcement and the likelihood that it
will play a significant role in the choices made. Second,
rewards or penalties should target factors that are deemed
to be important to people, i.e., factors that significantly
affect the particular behaviour. For example, transport
pricing will hardly be effective if travel costs are not an
important determinant of car use. In that case, people will
just pay the price and keep on driving. Third, the contin-
gency should be strong enough to get the desired behav-
Table 1 Pros and cons of push and pull measures
Push Pull
Restrictive Enlarge behaviour options
Makes car use less
attractive
Does not make car use less
attractive in an absolute sense
May elicit reactance Does not elicit reactance
Associated with negative
affect and attitudes
Associated with positive affect
and attitudes
More effective in activating
car use reduction goals
Less effective in activating car
use reduction goals
Lack of public support Public support high

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6 IATSS RESEARCH Vol.31 No.2, 2007
iour started38, otherwise people may not notify the reward
or punishment, especially when habits are formed. How-
ever, contingencies should not be too strong, because
people will strongly react to such policies. Moreover,
strong reinforcements may reduce intrinsic motivation to
contribute to the solution of traffic problems41,42. This
will especially occur when people can attribute their be-
haviour change to the reward or penalty. This may be
problematic, because research has shown that intrinsic
motivation may more strongly affect behaviour than do
extrinsic motivators such as financial incentives43. In
such cases, extrinsic motivators should be at least as
strong as to compensate for the reduction in intrinsic mo-
tivation. Moreover, powerful external consequences may
improve behaviour only temporarily, as long as the be-
havioural intervention is in place38.
3.5 Intervention planning
In general, intervention will be more effective if
they are systematically planned, implemented and evalu-
ated. Geller 38 proposed a general behavioural analysis
method which may assist policy makers to do so. This
so-called DO IT process comprises of four stages. The
process starts by defining the target behaviour (Define).
Interventions could best target behaviour that significant-
ly contributes to the solution of the problems at stake, and
aim at behaviour changes that are feasible and acceptable
to the public. Next, a baseline level of the behaviour
should be obtained by observing how often the target be-
haviour occurs under natural conditions, and which con-
ditions hinder sustainable behaviour or support unsustainable
behaviour (Observe). This reveals which factors may best
be targeted to change behaviour, and provides a baseline
for assessing the effectiveness of the intervention later.
Then, interventions should be developed and implement-
ed that target important factors hindering or supporting
behaviour (Intervene). As indicated earlier, interventions
may be aimed at changing external conditions (structural
strategies) or at changing perceptions and preferences
(psychological strategies). Finally, the effects and side ef-
fects of the intervention should be evaluated (Test). Based
on this, change agents can decide whether they need to
refine or replace a behaviour change intervention. More-
over, feedback may be given to the target population as to
inform them about the effectiveness of their efforts. This
may strengthen their commitment to change their behav-
iour. In sum, successful interventions should start with a
careful diagnosis of the particular behaviour, and end
with an evaluation of effects. As different groups may
have different reasons for (not) driving a car, interven-
tions may best be tailored to the needs, preferences and
circumstances of different target groups.
4. SUMMARY AND CONDLUDING REMARKS
This paper was aimed at illustrating how psycholo-
gists can contribute to sustainable transportation by
changing travel behaviour. It was argued that various
types of behaviour change may be needed to achieve
sustainable transportation, ranging from changes in
driving styles, mode choices, car ownership to changes
in location choices. These changes are associated with
different behavioural costs, which may vary for different
trip purposes. For example, for some trips (e.g., commut-
ing), travelling by public transport instead of a car may
be more feasible than for other trips (e.g., shopping),
and it may be quite easy to change travel time for some
trips, but not for others. In general, behaviour changes
will proceed according to a general cost-minimization
principle, with the less costly adaptation alternatives be-
ing selected first44.
In order to achieve behavioural changes, two ques-
tions need to be addressed. First, we need to understand
which factors cause behaviour. After all, policies will be
more effective if they target important antecedents of be-
haviour. Second, we need to examine which policies may
be effective, acceptable and feasible.
This paper first reviewed the rich literature on fac-
tors influencing the level of private car use. Car use is
very attractive and sometimes even necessary for many
different reasons. Many societies have been tuned to-
wards the regular use of a car. Moreover, car use has many
advantages over alternative means of transport, not only
because its instrumental function (i.e., a means to travel
from A to B), but also because of its symbolic and affec-
tive values (i.e., the car is a symbol for status and success
and a way to express yourself, and driving is pleasurable
and exciting). Empirical evidence for the significance of
these different motives for car use and the use of other
modes of transport for different types of trips is still lim-
ited, and needs to be studied further.
Because of its many advantages, car use is likely
to become habitual, making it more difficult to change.
Car use became common practice, and many people be-
came dependent on their car. That is, people presume the
availability of a car when making choices in daily life,
and as a consequence, they can no longer live without a
car. Although many people acknowledge the negative
consequences of car use (such as environmental prob-
lems, traffic noise, traffic unsafety, congestions), in gen-

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SUSTAINABLE TRANSPORTATION* – A Psychological Perspective – L. STEG
eral, they do not act accordingly. That is, for many, the
numerous individual advantages outweigh these collec-
tive problems. However, some people try to use their car
use as little as possible out of environmental concern.
From the above, we may conclude that many fac-
tors may and should be targeted to reduce the attractive-
ness and necessity of car use. In order to effectively change
car use, transport policies should not only be aimed at
reducing the attractiveness of car use, but at increasing
the attractiveness of other modes of transport as well.
Since many different factors make car use attractive, it is
unlikely that single policies targeting a few of these fac-
tors only will succeed in significantly changing car use. A
combination of policies, each targeting different factors
influencing car use (e.g., the available infrastructure, ur-
ban structure, the instrumental, symbolic and affective
qualities of cars and other modes of transport, awareness
of the problems of car use) is needed40.
Second, the paper discussed various strategies for
changing travel behaviour in order to safeguard collective
qualities. A distinction was made between psychological
strategies, aimed at changing individual perceptions and
motivations, and structural strategies, aimed at changing
external conditions as to make car use relatively less at-
tractive or feasible, and the use of sustainable transport
options more attractive and feasible. Psychological strat-
egies are mostly not very successful in changing behav-
iour in isolation, although individualised social marketing
approaches yielded promising results, probably because
in this case information is tailored towards the needs,
wants and perceived barriers of those involved. Structural
strategies can either reward “good” behaviour or punish
“bad” behaviour. In the transport domain, the latter (so-
called push measures) seem to be more effective in chang-
ing car use than the former. However, push measures are
less easily implemented because of lack of public support.
Policy acceptability may be strengthened when expected
(positive) effects of policies are clearly communicated.
Moreover, anticipated negative effects for individual
freedom may be compensated by implementing support-
ive policies aimed at facilitating the use of sustainable
modes of transport. This again highlights that a combina-
tion of policies is called for.
Finally, we argued that interventions aimed at
changing car use should be systematically planned, im-
plemented and evaluated. Interventions should target im-
portant antecedents of car use (as described in section 2).
Moreover, effects of interventions should be evaluated.
This enables change agents to communicate these effects
to those involved, which may strengthen their commit-
ment to contribute to the solution of the problems caused
by car use. Moreover, it should be examined whether ac-
tual effects are in line with the expectations of change
agents. Based on this, it can be decided whether a behav-
iour change intervention needs to be refined or replaced.
This paper provided a broad overview of psychol-
ogy and sustainable transport. For the purpose of this pa-
per, relevant topics could not be discussed in much depth.
More detailed discussions of the relevant topics may be
found in the literature listed in the references and in a
recent volume on threats from car traffic to the quality of
urban life, in which problems of car use, causes of these
problems as well as possible solutions are discussed45.
Obviously, psychology focuses on some relevant aspects
of the problems. Given the complexity of the problems,
and the many factors involved, policy makers should also
consider knowledge provided by other disciplines. A
multidisciplinary perspective will provide a more com-
prehensive view of the factors causing the problems and
possible solutions, and thus a richer basis for policy mak-
ing. I hope this contributions has highlighted that psy-
chologists have an important contribution to make in
reaching sustainable transportation.
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