اثرات توسعه پایدار از قیمت گذاری جاده ای خودرو: تجزیه و تحلیل تعادل عمومی قابل محاسبه برای اتریش

Nationwide car road pricing schemes are discussed across Europe. We analyse the impacts of such schemes with respect to environmental, economic and social indicators of sustainability, also quantifying the trade-offs among these three dimensions under different charging principles and revenue recycling options. In our analysis we employ a computable general equilibrium (CGE) approach, develop a modelling structure for private transport and provide detailed empirical analysis for the case of Austria. Regarding the social dimension, it has often been argued that poorer households (and commuters) would have to bear a disproportionate share of the road pricing burden. We find the contrary, i.e. a stronger negative policy impact on richer households, and on a small group of intensive car users. The choice of revenue recycling is able to ameliorate the negative social and economic effects of road pricing, without reversing the desired positive environmental effects. For political feasibility, questions of distributional impacts are most urgent and therefore we address them systematically within a quantitative framework.

Environmental challenges in transportation occurred repeatedly in history, an early example in modern times being the concern in the 1870s in London that, with a further growing population, the horse manure (an earlier form of transport-derived pollutant) would overwhelm the city.1 For the current transport system, environmental concerns have become increasingly important since the 1970s. Transport is now responsible for at least a quarter of world primary energy use and for a comparable share of CO2 emissions (Berechman, 2002). While initial responses to the environmental challenge in transport were primarily technological, there has since been a focus also on reducing and re-structuring transport demand (Berechman, 2002) and on using transport pricing policies (Viegas, 2003 and Hensher and Button, 2000). However, most of present transport policies still mainly centre on vehicle emission and safety standards, annual license duties and parking fees and thus may be classified as out-dated or, in the economist's jargon, “second-best” (see, e.g., Calthrop, and Proost, 1998, Nash et al., 2001 and Ubbels et al., 2002). Road pricing, a vehicle user charge based on distance travelled, is clearly highly suitable in addressing transport-related environmental problems since it allows differentiation of charges across location, time, vehicle type etc. (see, e.g., Johansson and Mattsson, 1995, Berechman, 1998, Sterner, 2002 and Santos, G. (Ed.), 2004). It combines the ability to untie congestion, to reduce air pollution, and to raise revenues for new infrastructure and other investment (Jakobsson et al., 2000, Parry and Bento, 2002 and May et al., 2002). For trucks, kilometre based road pricing systems have been introduced in Europe at various levels of sophistication, i.e. from section-charging on highways in various countries, and electronic charging on highways in Austria (2004) and Germany (2005), up to charging for use of the full road network in Switzerland (2001). In Sweden, a mileage tax for diesel trucks was in place from 1988 up to 2004.2 For private cars, charging in Europe has been introduced either section-wise for highways or for urban areas mainly in the form of toll rings, e.g. in Scandinavian countries and more recently in London (and similar as in other parts of the world, such as in Singapore). The discussion of nationwide kilometre based charging also for private cars has slowly taken off in various European countries (see e.g. Nash et al., 2001 and Ubbels et al., 2002). The introduction of extensive, nationwide road pricing also for passenger transport requires careful impact analysis. In terms of sustainability impact assessment, the European Union (EU), for example, asks for “careful assessment of the full effects of a policy proposal [that] must include estimates of economic, environmental and social impacts” (EC, 2001). As set out in Böhringer and Löschel (2006) in some detail, the quantification of trade-offs in such an impact assessment analysis calls for the use of numerical techniques and that one of these approaches, CGE modelling, “can incorporate several key sustainability (meta-)indicators in a single micro-consistent framework, thereby allowing for a systematic quantitative trade-off analysis between environmental quality, economic performance and income distribution.” (Böhringer and Löschel, 2006: 50-51). As passenger car road pricing remains a field of national policy responsibility, also within the EU,3 we develop a CGE model for a sustainability impact assessment at the national level of such policy. Within the different dimensions of sustainability, the economic one has been most broadly discussed for road pricing. The initial focus was the optimal pricing in the transport sector to combat congestion (e.g. Lindsey and Verhoef, 2001). Increasingly the environmental impacts of transport have been taken up in co-determining the optimal price (e.g. Mayeres et al., 1996).4 In our view least effort has been devoted to the social dimension. However, social questions of distribution and equity are of major importance for the acceptance of road pricing (see also Mayeres and Proost, 2001). The low public acceptance for car road pricing derives from the perception of road pricing as intrinsically unjust (Oberholzer-Gee and Weck-Hannemann, 2002) and as infringing on personal freedom (Jakobssen et al., 2000). Since income constraints can be identified as the key determinant for transport demand reductions when travel costs increase (Jakobsson et al., 2000), the burden of road pricing is likely to fall on poor households (see also West, 2004) and on households living in peripheral regions (Hammar and Jagers, in press). This article therefore aims to not only quantify economic and environmental impacts of road pricing, but to investigate the effects on those groups perceived as bearing the main burden of road pricing. A passenger transport focused computable general equilibrium (CGE) model is developed for this purpose. To better understand the distributional effects of road pricing, we distinguish four classes of income in our model. Thus, the present model goes beyond existing ones in several respects. First, and in some way parallel to earlier transport policy discussion, most of the models used so far to analyse road pricing are either limited to freight transport (e.g. De Jong et al., 2004 and Steininger, 2003) or they target urban road pricing or toll ring pricing only (e.g. Proost and Van Dender, 2001 and Mayerers et al., 1996). We focus on nationwide car road pricing. Second, while an increasing number of papers addresses the welfare effects of a tax suitable for internalising external transport costs (e.g. Nash et al., 2001 and Jansen and Denis, 1999), distributional aspects have hardly been considered in economic transport policy models. Third, in methodological terms, our approach unites modules from the sciences of transportation and economics to a consistent integrated assessment of economic, environmental and distributional impacts. The core ingredient in this merging is the calibration method of the economic passenger transport focused CGE model, integrating results of the pure heuristic passenger mode choice model. The paper proceeds in four steps as follows. In Section 2, the passenger transport focused CGE model is developed. In Section 3, transport and consumption databases are merged, a social accounting matrix is constructed which differentiates sufficiently between the various cost components of private car transport, and transport elasticities of substitution are calibrated for this model. Section 4 reports on the simulation results of nationwide car road pricing in various implementation schemes. Section 5 discusses the distributional, economic, and environmental impacts of this policy. A final section summarises the main conclusions and outlines key factors for increasing acceptability prior to the introduction of a car road pricing system.

In our analysis of car road pricing we explored the use of a transport oriented computable general equilibrium model for sustainability impact assessment. As in the literature so far the coverage of social impacts is rare, we put a main emphasis on quantifying distributional implications of car road pricing and potential trade-offs with the environmental and economic objectives. Based on an in-depth analysis of the effects of environmental transport policies, West (2004) concludes in a – partial equilibrium – joint analysis of vehicle choice and mileage that (i) demand elasticities of vehicle miles driven decline with income levels, and that thus (ii) distance-dependent policies, such as a gasoline tax or road pricing, are regressive only across higher income households but progressive across low income households. The higher degree of price-responsiveness of lowest income households produces this result. We find, however, in a general equilibrium model, and thus within a more integrative assessment acknowledging also overall feedback effects, that road pricing has a progressive impact across all income ranges, at least if consumption based welfare effects are chosen as an indicator for fairness. This result is steered by two effects which work in opposite directions. On the one hand, the strongest percentage reductions in car kilometres can be observed for the lowest (and the highest) income households: The lowest income household group experiences a high reduction since they usually drive small cars (with relatively low variable costs per kilometre driven) and a price increase of 5 Euro-cent implies a doubling of their variable costs (see Table 1). Households in the highest income group have low variable costs per kilometre, and therefore their reduction in mileage is higher than for the medium income households. This makes both groups less vulnerable to the implementation of car road pricing than other income groups. On the other hand, pre-policy car transport demand levels strongly increase with income. This works clearly progressive in car road pricing implementation, and tends to dominate the former effect. Investigating the burden on different income groups should be a starting point to be further addressed by future research. It may well be that many of the “really poor” households are categorised not within the lowest income group (which surely includes many young single households, students, single retired, etc.), but within the second lowest income group, which may include households with single income, but more household members. Also, we focus on the distribution of costs of car road pricing policies only. While we quantify overall benefits, such as health benefits or benefits from reduced congestion, we do not analyse their distribution across income groups. For a final evaluation of distributional impacts this would be necessary. Of these health and reduced congestion benefits, a pre-analytic assumption could be that the former might more strongly benefit the poor (since they are less able to flee environmental burdens), the latter the rich (who both drive more and have higher time costs). However, questions of fairness are not the only ones relevant for increasing the acceptance of road pricing prior to introduction. Obviously, one natural extension here is proper communication of the purpose and effects of road pricing, i.e. road pricing should be anchored as a justifiable environmental policy, not only as an instrument for revenue raising or as a measure primarily addressing congestion, and it should be discussed relative to other policy options (see, e.g. Odeck and Bråthen, 1997, Oberholzer-Gee and Weck-Hannemann, 2002 and Hammar and Jagers, in press). Also, the design of compensation is essential, in order to meliorate the effects on certain groups, particularly on those identified as “road pricing victims” (or captives). As argued before, the characteristics used to identify these groups need to be investigated more intensively (income and household location being only two of many possible indicators). Furthermore, revenue spending can have a significant impact on the effects of road pricing. In particular, if households are compensated in a lump-sum fashion for higher transport expenditures (as is assumed in policy scenarios A to D), small welfare burdens for the poor come at the price of GDP reductions and ambiguous employment impacts (whereas if revenues are spent such as to lower labour taxes, the effects of road pricing on GDP and employment are clearly positive). Thus, we can confirm that revenue spending is an important element in the appropriate design of a road pricing scheme, in addition to the “sales arguments” put forward by others (Calthrop, and Proost, 1998, Jakobsson et al., 2000, Oberholzer-Gee and Weck-Hannemann, 2002 and Proost et al., 2002). Finally, in discussing the benefits of introducing nationwide road pricing, fuel taxes are often seen as a preferable substitute. While fuel taxes are easier in administration, a road pricing scheme has mainly three advantages. First, it allows for regional and peak-time differentiation, possibly even in short-term response to weather related emission dispersion conditions. Second, while the range of potential fuel tax increments is limited due to potential tax avoidance caused by refilling in neighbouring countries (see Calthrop and Proost, 1998; or Ubbels et al., 2002, for a formal analysis; for an empirical application, see De Borger et al., 2004), road pricing allows for national independence to set (car) road pricing rates, by which also all users (domestic and foreign) within one's territory are charged. Third, the visibility of full user costs per kilometre travelled is higher for a permanent cost counter, like the road pricing on board unit (OBU), than for a fuel tax.