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Transportation Research Part A 42 (2008) 901–909

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The effect of transportation policies on energy consumptionand greenhouse gas emission from urban

passenger transportation

Pascal Poudenx *

School of Community and Regional Planning, University of British Columbia, #433-6333 Memorial Road, Vancouver, BC, Canada V6T 1Z2

Received 21 September 2005; accepted 1 January 2008

Abstract

This paper offers a brief journey through twelve major cities with various policies in place to curb private vehicle use andassesses their success in term of energy consumption and greenhouse gas emission.

Every region reviewed including Singapore is experiencing increase in energy use, greenhouse gas emissions and/orprivate vehicle ownership. In Europe, several regions improved transit quality and increased its ridership attractingnon-motorized modes users instead of private vehicle users effectively increasing the total energy consumption.

The author argues that policies aimed at reducing private vehicles use are failing because they do not incorporate thereality of human propensities for accessibility and comfort and they unsuccessfully try to attract customers toward servicesof lesser perceived quality. The demand for both accessibility and comfort will likely continue to grow with rising standardsof living and will be met regardless of the environmental impact. Instead of attempting to constrain private vehicle use, theauthor suggests raising the competitiveness of alternate modes by investing in more attractive environments for non-motorized modes and designing transit systems actually capable of competing with private vehicles in term of perceivedservice quality while offering improved environmental performances.� 2008 Elsevier Ltd. All rights reserved.

Keywords: Urban passenger transportation; Energy; Greenhouse gas; Transit; Investment strategy

1. An overview of urban transportation

Road transportation in general and the use of automobiles in urban areas in particular are blamed formany problems. From congestion to accidents, from energy dependency to air pollution, and from urbansprawl to obesity, the list is long and so is the number of policies developed to mitigate these problems, fromtravel demand management (TDM) techniques to intelligent transportation systems (ITS), and from emissiontargets to change in land use.

0965-8564/$ - see front matter � 2008 Elsevier Ltd. All rights reserved.

doi:10.1016/j.tra.2008.01.013

* Tel.: +1 604 822 1898; fax: +1 604 822 3787.E-mail address: poudenx@interchange.ubc.ca

902 P. Poudenx / Transportation Research Part A 42 (2008) 901–909

Here are some figures to get a sense of the issues:

� Road traffic injuries are now the leading cause (25%) of injury-related deaths worldwide (WHO, 2002a). Itwas the ninth overall cause of death in 1990 and will likely become the sixth by 2020 in developing countrieswith India in particular bearing most of the burden.� A recent study in Atlanta showed that ‘‘each additional hour spent in car per day was associated with a 6%

increase in the likelihood of obesity” (Franck et al., 2004).� The World Health Organization also lists traffic noise as a major factor in decreasing quality of life since ‘‘it

is the only environmental factor for which complaints have increased since 1992” (WHO, 2002b).� Urban congestion in the US in 2002 was blamed for 5.7 billions of gallons of oil wasted (2.8% of the total

US Transportation sector oil consumption1), and 3.5 billion of hours lost (12 h/cap/yr2) for a total cost of63.2 billion dollars (0.57% of US GDP2) (Schrank and Lomax, 2004).� A 1999 study in France, Austria and Switzerland, revealed that emissions from road transport alone caused

21,000 premature deaths a year while direct road accidents accounted for 9947 deaths over the same periodin these three countries (Kunzli et al., 2000).� In the Lower Fraser Valley region in British Columbia, Canada, cars and light trucks are the largest con-

tributors to the total regional emissions of CO (69%), VOCs (31%), CO2 (28%), and NOx (24%) (GVRD,2003a).

This situation is only expected to worsen because of two trends which have been observed worldwide. Firstis the general increase in the standard of living (Salvatore, 2004). Second, as income increases so does people’sreliance on faster transportation modes since individuals are only willing to spend so much time travelling(1.1 h per day on average). Consequently, the world is shifting toward faster modes, which also are moreenergy intensive (Schafer and Victor, 1999). Since fossil fuels are the main source of energy, emissions of com-bustion by-products are also expected to increase. Developing countries are expected to account for 52% of thetotal worldwide mobility in 2050 with 54,545 billion passenger kilometre (pkm) (versus 8 562 billion pkm or37% in 1990) while the industrialised countries share will shrink from 53% in 1990 (12,372 billion pkm) to 41%(43,759 billion pkm) in 2050. The overall effect is that carbon emissions from passenger transport are expectedto increase worldwide from 0.8 GtC in 1990 to 2.7 GtC in 2050.

An increase in the number of private vehicles has already been observed in many countries, with the annualrate at more than 10% in Chile, Mexico, Korea, Thailand, Costa Rica, Syria, Taiwan, and even 15% in China(Gakenheimer, 1999). The income-vehicle relation is not however linear. A surge in demand is observed as acountry per capita income enters the US$ 6700–11,500 range (in 1985 US$) (Soligo and Medlock, 1997). Forinstance in 1999, Mexico was at $ 6238 (in 1985 US$) per capita and is one of the countries where the demandfor private vehicles is expected to explode (Bauer et al., 2003).

The reasons behind this car ownership increase also differ depending on the region. Poland is a good illus-tration of the ‘‘economies in transition” where the fall of the communist regimes has had a major effect onurban transportation. Public transit used to account for more than 80% of all urban trips in Poland, as in mostof Eastern Europe (partly because car ownership was restricted), but transit mode share has been steadilydecreasing since the regime changes while transit fares and car ownership have been increasing. The Polishpublic transit lost one third of its ridership (from 9 to 6 billion passengers per year) in only four years (from1988 to 1992). Meanwhile the auto ownership per capita increased by 42% and this is expected to continue inthe foreseeable future (Pucher, 1995). The same trend has been observed in Hungary, former Czechoslovakia,and former Eastern Germany.

As for the most populated country in the world, China, the estimated per capita income was at US$ 3550 in1999, seemingly still far enough from the previously mentioned threshold which triggers a surge in vehicledemand. However, the Chinese central government has prioritized the development of the auto industry inorder to foster the country’s economic growth (Gan, 2003). Consequently, the private vehicle industry that

1 Based on 200 billions of gallons consumed by the US Transportation Sector in 2002 (DOE, 2004a).2 Based on 288 millions inhabitant and a GDP of 10,480.8 billion dollars in 2002 (DOE, 2004b).

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did not appear until the 1980’s was already producing 600,000 vehicles in 2004 with an annual rate of growthof 40%. There were 13.2 million vehicles in 1998 in China and by 2020 the urban vehicle population is expectedto increase 13–22 times. The sheer number of vehicles is expected to have major consequences in term ofenergy demand and greenhouse gas emission.

2. Study objectives

With five billion people jumping on a private vehicle bandwagon already cherished by one billion people indeveloped countries, it is obvious to see why many predict the situation is going to go from bad to worse. Gov-ernments are therefore working on various policies to address these issues. Developing transit systems is oneoption since they use less energy and produce fewer emissions per passenger moved. Indeed, private vehiclesconsume around 2–3 MJ/pkm (106 J/pkm) while Diesel buses are close to 1 MJ/pkm and electric trolley busesor light rail system are at 0.3 MJ/pkm (Schafer and Victor, 1999). While switching to a fossil-fuel poweredmode with reduced energy consumption reduces greenhouse gas emissions proportionately, switching to a dif-ferent energy currency may allow even further reduction. One example is switching from fossil-fuel poweredbuses to electric trolley buses. If the electricity is produced by hydropower, the greenhouse gas emissions areminimal (e.g., 22 g/kW h in British Columbia, Canada) (BC Hydro, 2005). And even if electricity comes froma generating plant which uses fossil fuels, more emissions control options are available for fixed sources thanfor mobile sources and therefore substantial emission reduction can be achieved. And benefits goes beyondsimple savings in energy costs as the WHO states that ‘‘reducing greenhouse gases through action in the trans-port, energy and industry sectors would have immediate health benefits [. . .] The greatest health benefits willstem from integrated policies covering technology, urban planning, the speed and safety of traffic, quality oflife and the promotion of walking, cycling and the use of public transport.” (WHO, 2000).

So, if many agree that building energy efficient transit systems and convincing people to use them is so ben-eficial, what have been the real-world success stories? This question seems particularly relevant for a countrylike Canada which is now bound by the Kyoto protocol to reduce its annual greenhouse gas emissions duringthe 2008–2012 period to 6% below its 1990 level while its actual emissions keep on increasing. Indeed, Can-ada’s latest inventory showed that 2003 total emissions were 24.16% higher than in 1990 and light-duty vehi-cles and trucks emissions, which represent 12.5% of the countries total emission were also 20.78% higher(Environment Canada, 2005).

The compilation hereafter presented is of course not extensive but it is intended to provide a snap-shot ofthe situation and show whether or not transportation policies are generally successful at reducing energy useand greenhouse gas emissions from passenger transportation in urban areas.

Urban passenger transportation may be defined in a simple manner as ‘‘an ensemble of means to provideaccessibility to individuals in an urban environment”. Policies addressing urban transportation may thereforefocus on the ‘‘means to provide accessibility” (e.g., setting up transit systems, limiting vehicles energy use oremissions, promoting communication systems to improve accessibility without increasing the need for mobil-ity), on the individuals and the decisions they make (e.g., taxing the use of certain modes, providing incentivesto use different modes, educating), or on the urban environment (e.g., promoting mixed-use dense communi-ties where the need for motorized transport would be reduced). Let us now review some of these policies.

3. Review of policies

3.1. Change in land use: Curitiba

Land use change is recognized as a major tool to influence the use of certain transportation modes (seeEwing and Cervero, 2001, for a review of over fifty empirical studies) and is at the base of planning conceptssuch as ‘‘new urbanism”, ‘‘smart growth”, and ‘‘sustainable development”. The Greater Vancouver RegionalDistrict clearly acknowledges its potential when stating that ‘‘government policy makers have four majorslever available to steer the transport system towards their desired goals. They are: control land use, applyTDM, adjust transport services level, and supply transport capacity” (GVRD, 1993). One of the major

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challenges with land use strategy is the time frame, since significant changes require decades to take place.However, results might eventually appear as illustrated by the example of Curitiba in Brazil.

Curitiba is the capital of Parana, one the richest state of Brazil. The city itself has approximately 1.6 millioninhabitants with an average density of 49 inhabitants per hectare and the whole Metropolitan region has 2.7million people (Macedo, 2004). The current city master plan was first introduced in 1966 when the city hadaround 500,000 inhabitants and because the same political group has been in power ever since, only minormodifications have been made to the initial plan. The transportation network of Curitiba is based on the‘‘wheel and spokes” model with five axes radiating from the downtown core and ring roads connecting thebranches. The land use is such that the areas with highest densities are located along the five main transpor-tation corridors and density decreases as distance from these corridors increases. Also some areas have exclu-sive or preferential use by pedestrians and ring roads allow communication between outside neighbourhoodswithout having to go downtown. Each axis is composed of three roads: a central one with a segregated lane forexpress buses and one-way roads on each side for the slow traffic. One city block away on each side are one-way roads reserved for the rest of the high-speed traffic.

There were in 2004 2160 buses transporting 1.9 million riders on weekdays. The transit mode share reacheda respectable 41% in 1987 despite the fact that the cost of commuting can represent up to 35% of the minimumwage (Smith and Raemaekers, 1998). Even though this transit mode share appears high when compared todeveloped countries (typically 3% in the US, 25% in Europe), cities in developing countries usually have highertransit share figures (65% in Asia) (Kenworthy and Laube, 1996). Curitiba density is quite high (49 persons perhectare) but the overall transportation system energy efficiency is 10 GJ/cap/yr, comparable to one of otherBrazilian cities (7 GJ/cap/yr in Recife and 13 GJ/cap/yr in Brazilia).

So, the success of this strategy as a means of reducing energy use is not obvious when compared with othercities without such large-scale program. Car ownership is also relatively high around 40% and bus ridership inCuritiba has not been increasing in the last 40 years despite the implementation of this large-scale plan. More-over, critics consider that the policy has been too focused on the transportation inside Curitiba, ignoring theuncontrolled growth outside the area, and causing a lack of investment in other domains. For instance, lessthan half of the population was connected to the sewer system in 1990. Finally this land use policy is alsoblamed for creating social segregation by artificially pushing up land prices along the main corridors and forc-ing the poor away (Macedo, 2004).

3.2. Strong transportation demand management: Singapore and Hong Kong

Singapore exemplifies strong TDM policies. Its two-prong strategy relies on limiting car ownership andproviding adequate rapid transit.

With four million inhabitants, Singapore had 688,811 vehicles in 1999 and only 3122 km of road (or 4.5 mof road per vehicle) (Goh, 2002). Car use restrictions were initiated as soon as traffic problems appeared in thecentral business district (CBD) in the mid-seventies. First, an ‘‘Area Licensing Zone” was set to restrict theaccess to the CBD, later combined with high taxes and parking charges. This reduced rush-hour traffic by45%, decreased accidents by 25% and increased traffic speed by 20%. However, these policies, along with highimport duties and registration fees, did not prevent the total number of cars from continuing to grow so thegovernment eventually set up in 1990 a vehicle quotas system (VQS) in which a set number of ‘‘Certificate ofEntitlement” were auctioned every month. The effect was to drive the price of these certificates up and it wasestimated that in 1995, owning a Toyota Corolla 1.3L cost US$64 900 making it technically out of reach fortwo-thirds of the population (Seik, 2000). Road pricing schemes (e.g., tolls) were then added in 1995 andupgraded to an electronic version in 1997 effectively reducing traffic on controlled roads by more than 40%and increasing public transit speed by 16%. The electronic version was not only more flexible, allowing trafficto be rapidly directed to less-used roads, but also was less intrusive since vehicles did not have to stop at tollbooths and overall the system was perceived as more fair by the public.

The second element of the policy was to provide adequate public transit. Like many Asian cities, the densityin Singapore was already high enough to accommodate such a strategy successfully. An efficient mass rapidtransit opened in 1987 to support an already extensive bus system and a light rapid transit was added in1999. From an energy perspective, these measures have been successful since the average-rush-hour speed

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was 30 km/h in 1990, twice the regional average which meant less idling and less wasted fuel. Using scenariosimulation (Pacudan, 1997), fuel consumption savings from these measures were estimated at 43% (741 mil-lions litres of gasoline were consumed in 1990 versus an estimated 1 300 billion litres without the variouspolicies).

However the 2000 Census showed that the percentage of people commuting to work by car has beenincreasing from 13.4% in 1980, to 18.1 in 1990 and to 23.7 in 2000 (SDS, 2001) and between 1994 and2004, the fleet of private cars grew 31.7% from 295,525 to 289,282 vehicles while population grew by 23% from3.4 to 4.2 million people. The mere fact that cars continue to attract more and more customers in an environ-ment as constraining as Singapore is quite indicative of the forces pushing people to own private vehicles.

Hong Kong is in a similar situation. Despite a GDP per capita similar to the UK, the car ownership is only48 vehicles per 1000 inhabitants versus 377 in the UK (for comparison: Japan: 325, USA: 485) (Cullinane,2003). Density is often used as an explanation. Indeed Hong Kong’s 6 096 persons/km2 dwarfs even NewYork or London’s figures of 744 and 678, respectively. However, there are other factors. First, registrationtax and annual licensing fees make the purchase of a car 50% higher than in New York and 100% higher thanin Sydney, but still only half the price in Singapore. Similarly, fuels taxes, parking fees, road and tunnel tollsadd to the operating cost. As a consequence, public transit represents over 90% of the motorized journeys.However recent trends show that cars are gaining ground. Car ownership increasing by 13.3% between1996 and 2000, while the total distance traveled went from 10 561 millions vehicle kilometre traveled(VKT) in 1994 to 11,579 VKT in 2002 (HK-EDP, undated).

The attitude of Hong Kong’s inhabitants toward private vehicles was revealed by a survey among youngpeople indicating that ‘‘over 70% of the respondents showed some intention of buying a car in the future”

(Cullinane, 2003). And the problem raised by another survey among car owners is that once a car is purchased,it rapidly becomes a necessity and the feeling is reinforced over time (Cullinane and Cullinane, 2003). Conse-quently, an average Hong Kong car owner manages to drive over 5000 km a year (over 13 km per day) in anarea approximately 20 by 20 km large. According to the author of the survey, efforts should be made to keeptransit riders because once they switch modes the likelihood of regaining their patronage is minimal. If this isalso valid in industrialised countries where car ownership is already extremely high, this statement illustrateswell the challenge faced by western transit operator.

The only example of a strong TDM policy in a large western city is London with its congestion chargingscheme (CCS) initiated in February 2003. Since then, traffic volume decreased by 15% while congestion,defined as time spent in stopped or slow traffic, was reduced by 30% and traffic outside the zone only expe-rienced ‘‘small increase satisfactorily managed” (TfL, 2004). Consequently, there has been a 20% reductionin CO2 emissions over the area. This success should be put in perspective since the area concerned by thescheme represents 22 km2 or 1.3% of the total area of the Greater London where car ownership continuesto increase (16% between 2000 and 2005 from 360 to 410 vehicles per 1000 inhabitants) (GLA, undated).

3.3. Transit systems improvement: European examples

While the previous examples were focused on reducing automobile use, the following cases show policiesfocused on transit development like in Hamburg, Munich, and the Rhein-Ruhr region in Germany, Viennain Austria and Zurich in Switzerland (Pucher and Kurth, 1995). These five areas started by developing an inte-grated regional transit system where one authority oversees all of the transit activities. Out of these fiveregions, Munich and Zurich have been able to actually increase the transit share in the total number of motor-ized trips (from 30% in 1975 to 41% in 1993 for Munich and from 52% to 62% between 1980 and 1990 inZurich). However, the three other regions have only been able to mitigate the drop in modal split (from41% in 1975 to 32% in 1990 in Hamburg, 36% in 1975 to 25% in 1993 in the Rhein-Ruhr region and 49%to 44% between 1980 and 1990 in Vienna) despite an increase in absolute number of riders, reasons being thatpopulation and overall mobility increased even faster.

Such successes are explained by the amelioration provided. First, the service was expanded with more lines,faster modes (e.g., grade-separated bus lanes, light rail) and higher frequency. The quality was improved withmore reliable schedules, better connections and better services such as park-and-ride or bike-and-ride facilitiesas well as better weather protection at stops and more attractive stations. Aggressive marketing campaigns

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were used with all the media available (billboards, radio, TV, newspapers, pamphlets. . .), promoting the envi-ronmental and social benefits of transit as well as setting up more convenient fare schemes such as monthlyand employer-subsidized passes. Finally, the fares themselves have been reduced to attract more customers.Now, one can see the problem arising, more operating expenditure and fewer revenues from customers requirea vast increase in public subsidies. From 1980 to 1993 the government subsidies grew after adjustment forinflation by 63% in Hamburg, 38% in Munich, and 78% in Rhein-Ruhr. As for Vienna, it has been an 86%increase from 1985 to 1993 and for Zurich a 16% increase from 1990 to 1993. One of the explanations oftenput forward is the low elasticity of public transport demand, which requires a large change in price for a smallchange in the demand. It was also argued that the subsidy mechanisms might not have been adequate sincethey were based on increasing the vehicle kilometres of service supplied instead of actual passenger trips. How-ever, a passenger trips scheme would have probably pushed operators to limit their service to the route withhighest occupancy instead of developing region-wide networks.

Another successful example is Freeburg in Germany (FitzRoy and Smith, 1998). Ridership of local publictransport rose from 27.7 to 65.9 million trips from 1983 to 1995 while the population only grew from 201,000to 227,000. The modal split in 1982 was 39% by cars, 35% by foot, 15% by bicycle and 11% by public transitand it became 10 years later 42% by car, 21% by foot, 19% by bicycles and 18% by transit. It was concluded‘‘the resulting absence of any significant change in the modal share for private motor vehicle trips between1982 and 1992 must rank as quite an achievement given the massive increase in car ownership levels duringthis period”. However, the modal share evolution seems to indicate that transit actually took former pedes-trians not former drivers in their new patronage so the share of motorized trips actually increased from50% to 60% meaning than more energy was also consumed. However, the effect on greenhouse gas emissionsis not as straight-forward since the transit system in Freeburg is in part composed of electric trolley buses andthe emissions therefore depends on the fuel-mix used by the local utility company.

The factors put forward for explaining this improvement were an extension of the tramway system, per-ceived as more reliable and more comfortable than buses, a monthly pass freely transferable among friendsand family members, and an access to the region-wide transit network. One noticeable point is that the frac-tion of the operating cost recovered by tickets did not decrease. And finally, these improvements were accom-panied with a pedestrianization of some areas, traffic calming, the raise of parking fees, and the conversion ofsome car parking spots into bicycle stalls.

3.4. Promoting transit in North America

The need for subsidies is even more important in North America where lower densities make it even moredifficult for transit authorities to balance a budget. Houston and San Diego systems achieved significantincreases in transit ridership during a period in which most transit systems were experiencing losses. Between1992 and 1998, the US average number of boarding declined by nearly 4%, while boarding increased by 9.2%in Houston and 3.9% in San Diego. This however was only realised because of ‘‘large service increases and farereductions . . . made possible by large subsidies from federal, state and governments” (Kain and Liu, 1999). In1998, San Diego received an operating subsidy of $21 per capita while the operating and total costs amountedfor $44 and $72. The respective figures for Houston were $57, $76 and $109.

Vancouver is a fairly unique example in North America where one of the admitted strategies is to let thecongestion worsen in order to convince people to use transit (GVRD, 1993). The land use policy is to orientpopulation growth toward a few secondary centres in the hope of developing several of these mixed-use high-density zones where the need for personal vehicles would be reduced. In 1992, 83% of all journeys in the regionwere done in private automobile, 9% by transit and the remainder by bicycle and foot. A 10-billion dollars-over-30-years plan was then announced and one of the objectives was to bring transit mode share up to 18%by 2021. The policies also included expansion of the transit fleet, installation of HOV lanes and bridge tolls.Early estimates forecasted that all of these TDMs combined could save approximately 113 millions litres ofgas annually (a 5% reduction in total energy use by the road transportation sector) (Lim, 1998). By 2000,the greenhouse gas emissions had continued to rise (GVRD, 2003b) and a 2002 update showed that vehicleownership was rising faster than the population growth (1.9% versus 1.3%) (GVRD, 2002). The proportionof trips made by transit during the morning peak hour did however rise from 11.3% to 12.5% between

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1994 and 1999. In a 2004 update (GVTA, 2004) it was admitted that the initial target of 17% transit marketshare during rush-hour travel by 2006 would be difficult to achieve since it was still only 11% in 2003. Simi-larly, some HOV lanes had been installed but bridge tolls have yet to be set up. The initial increase in the busfleet from 950 in 1993 to 1800 in 2006 was also behind schedule since the 2003 fleet was around 1 200 buses.Finally, the transit mode share during weekday was also below target, still around 11%. All of this illustratesthe difficulty of fighting the trend. Car ownership and greenhouse gas emissions just keep on increasing andtransit modal share does not progress as fast as expected.

4. Analysis of the observed trends

So why, despite strong policies and large amounts of money, does transit share have so much difficultyincreasing while car ownership steadily rises?

Understanding people behaviour is certainly one of the keys to unlock the situation and the signs are notencouraging for transit systems. When people are asked about their commute in the US, it is not always con-sidered a bad thing. People actually appreciate the time spent alone in the privacy of their vehicle where theyescape from their hectic life. Half of them do not consider that their commute is too long (Stropher, 2004).People enjoying their time in their car is not a problem per se, but it becomes one when we consider theamount of energy used and greenhouse gases emitted while doing so.

Some insights on how and why people use their car are provided in a survey done in UK where 69% of alltrips are less than 5 miles long and 25% were less than 1 mile long. Cars are used in 50% of the first trips and in17% of the second (Mackett, 2003). When asked why they were using their car the respondents declared indecreasing frequency that they had heavy goods to carry (19%), were giving a lift to someone (17%), wereshort of time (11%), considered it was too far (11%), decided it was more convenient than transit (10%). Whenasked if they thought there could be alternative ways, 22% did not see any, while 31% admitted walking and31% thought of transit. Now the million-dollar question for all transit authorities: what would it take to makethem switch?

Logically, the 22% who did not see alternatives did not think that anything could make them change theirmind. Of the remainder, 21% said that nothing specific would make them switch, 23% would make the switchif transit was improved, 9% required better personal organisation and only 2% considered a reduction in costas part of the solution. This really seems to highlight the challenge facing public transit. A significant part ofthe population knows it is an option but simply decides not to use it. As for others, there are some real incon-veniences. Similarly a study in New York showed that commuting by transit was a stressful event particularlywhen transfers occurred (Wener et al., 2003). The study suggested that reducing the number of transfers wouldsignificantly decrease the stress level and therefore improve the perceived quality of the service.

Another strategy consists of educating people. It is believed that providing the proper information will suf-fice to make people leave their cars at home. Unfortunately, there is apparently a twist as shown in an eight-week long field experiment with 350 private automobile users in Holland (Tertoolen et al., 1998). Participantswere asked to record their daily car use and every two weeks received individual consultation where some werepresented with information on the environmental effects of their behaviour, some with information on thefinancial costs of car use, some with both information, and the last group received no information at all.All were also provided with information about alternative modes of transportation. In a pre-test study, every-body indicated their willingness to reduce their mileage but a post-test analysis showed that nobody actuallydid. Moreover, the feedback provided generally did not alter the participant perception of their own environ-mental impact but even more surprisingly a combination of information ended up having a negative impact onthe participants’ receptivity toward some environmental policy campaigns. The authors concluded that someinformation campaigns might create psychological reactance, meaning that people faced with the prospect ofmeasures restraining their freedom will tend to modify their behaviour in order to re-establish their freedom.The non-reduction in mileage was explained with the concept of psychological dissonance. When people arefaced with evidence of discrepancies between their attitude and their behaviour, they are more likely to modifytheir attitude rather than their behaviour. This is apparently why once people realized the impact of their driv-ing behaviour, they ended up downplaying these impacts rather than altering their driving habits. Similarly,they might argue that they have the right to pollute for the very reason that they pay taxes.

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A different study showed that habits also have a deep effect on behaviour. Strong habits are a ‘‘highly effec-tive moderator of the relation of personal norms and behaviour:” (Klockner and Matthies, 2004). In orderwords, you cannot teach old dogs new tricks. Policies aiming at modifying behaviour are more effective whenthe habits are weaker. Unfortunately, daily commuting falls in the very strong habit category and the authorssuggest this is the reason why education campaigns do not succeed at convincing people to switch modes.

5. Conclusion

This journey through cities with a wide range of environments, densities, modal splits, and policies revealedsome common features.

First is the overall increase in private vehicles ownership. No matter if the mode share of automobiles islow, as in Asia or South America, or very high, as in Europe and North America, the trend is here: peopleare buying more cars everyday and once they have them, they use them. Consequently, the energy use andgreenhouse gas emissions from urban passenger transportation are continuing to increase.

The second common feature is the general stagnation of transit modal share. In the rare instances when anincrease in this mode share was observed like in Germany, it appears that ridership was taken from non-motorized modes, which leave the energy consumption and greenhouse gas emission issues unresolved. Thisswitch however suggests that a service quality issue is at the heart of the problem. As a general trend, peopleonly switch to services with higher perceived quality, currently from non-motorized modes to transit, and fromtransit to private vehicles. Consequently, it seems that transit and non-motorized modes will have to bebrought to an acceptable level of quality first before a possible transfer in ridership from private vehiclescan occur. Public education campaign trying to convince people to switch to services with a lower perceivedquality are not working and continuously pouring very large amounts of public funds into the promotion andexpansion of poor quality systems is wasteful. One option to seriously consider is therefore to invest in qualityimprovement of transit systems instead of quantity increase. The difference in the evolution over the past cen-tury of buses and trolleys when compared to automobiles should convince anyone that investment in transitdesign, research and development is long overdue.

In conclusion, reducing the environmental impact of urban transportation by promoting transit and non-motorized modes over private vehicles has not worked so far partly because the environmental advantages ofthe formers are dwarfed by the convenience of the latter. In light of this conclusion, investing more publicfunds without addressing the source of the problem is a very poor resource allocation strategy. These policieswill continue to fail until the irremovable precedence of self-interest and convenience over common good andenvironmental issues is taken into account. The demand for accessibility and service quality only gets strongeras level of affluence rises. The challenge is to provide both while reducing urban transportation’s aggregatedimpact, basically having the cake and eating it too. A logical recommendation is therefore to invest into servicequality improvement, such as building attractive environment for non-motorized modes and developing tran-sit modes actually capable of competing with the comfort and convenience of private vehicles while offeringbetter environmental performances. After all, the situation is quite clear: the aggregated impact of urbantransportation has to decrease while the increasing demand for accessibility will be met one way or another.It is now up to us to meet this demand in the most environmentally benign way possible.

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