IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change Transportation and urban planning

Transportation is a key development issue. Transportation is also one of the fastest growing end-use sectors in terms of CO2 emissions in both the developed and the developing world. The level of these emissions results from the combination of the distances travelled by goods and people, and the set of technologies used to make these journeys. Demand for and supply of transportation are largely inelastic in the short-term, but become elastic in the longer run as people and activities change location, as new infrastructure is developed and as preferences evolve. A very wide array of policies affects these long-term dynamics. The set of transportation technologies available at time, and their relative costs, are also influenced by public policies.

Three examples of how public policy choices affect transportation supply, transportation demand, technology, and ultimately emissions from the transport sector are discussed in this section: one of congestion policy, one of urban planning at city level, and the other of national policy driving urban planning. The first example is from the City of London, where a congestion charge was introduced in February 2003 to reduce congestion. Simultaneously, investment in public transport was increased. Early results suggest that congestion in the charging zone has reduced by 30% during the charging hours, that CO2 emissions have been reduced by 20%, and that primary emissions of NOx and PM10 have been reduced by 16% (Transport for London, 2005). However, the cost-benefit ratio of the operation is questioned (Prud’homme and Bocarejo, 2005; Santos and Fraser, 2006). Other examples of how non-climate transportation policies can impact on emissions are given in Section 5.5.

The second example is the development and steady implementation of an integrated urban planning programme in the city of Curitiba (Brazil) from 1965 onwards. This has allowed the city to grow eight-fold from 1950 to 1990, while maintaining 75% of commute travel by bus – a much higher public transport modal share than in other big Brazilian cities (57% in Rio, 45% in São Paulo) – as well as little congestion. As a result, Curitiba uses 25% less fuel than cities of similar population and socio-economic characteristics. Two characteristics of the programmes seem to have contributed particularly to its success: (i) integration of infrastructure and land-use planning; and (ii) the consistency with which successive municipal administrations have implemented the plan over nearly three decades (Rabinovitch and Leitman, 1993).

The third example concerns urban planning in the United States and Europe (and Japan), the latter being on average rather compact while the former exhibit important sprawl. Nivola (1999) notes that this difference cannot be explained only by differences in demography, geography, technology or income. He argues that the combination of public choices is responsible for most of the differences in urban sprawl between the USA and Europe. Such policies include: (1) a bias towards public financing of roads to the detriment of other modes of transportation in the USA - against a more balanced approach in Europe; (2) dedicated revenues for highway construction in the USA - against funds drawn from general revenues in Europe; (3) lower taxes on gasoline in the USA than in Europe; (4) housing policies more geared towards supporting new homes: (5) a tax system more in favour of homeowners in the USA; (6) lower support from the federal government to local governments in the USA than in Europe; and (7) the quasi-absence of regulations favouring small in-city outlets against shopping malls in the USA. In turn, this difference in urban planning generates widely different transport demand, energy consumption (Newman and Kenworthy, 1991), and CO2 emissions. Per capita CO2 emissions from travel in the USA are nearly three times as high as in major European countries, due mostly to a larger number of journeys per capita and a higher energy intensity (Schipper et al., 2001). A key point in the analysis made by Nivola (1999) is that most of these consequences were totally unintended, as these policies were adopted for non-transportation reasons (let alone for emissions reasons).