Transport is a cornerstone of modern civilisation, but at what cost? Heavier than you might think.
Decoupling is more than just a sustainable development buzzword. It essentially means slowing, if not reversing, the growth in environmentally damaging activities in relation to economic expansion. Indeed, without decoupling, sustainable development would probably be unachievable.Some areas of economic activity have decoupled: industrial output from energy consumption and CO2 emissions in the EU, for instance – its growth in activity has not led to a similar growth in pressure on the environment. But transport is one area where decoupling has simply not happened. Technologies have got cleaner, with modern engines polluting less, but any benefits from this have been outweighed by the effects of the rising stock of vehicles. In fact, mechanised transport has taken a brutal toll on the Earth’s environment since its emergence a century or so ago. Air pollution, land-take, road and air fatalities: many of us may have become used to all this or fatalistically see it as the price of progress. Yet these heavy economic, social and environmental costs are set to get worse.Travel may be great, but a business-as-usual approach to transport is not on. Political leaders know this and some serious efforts have been made, whether to improve public transport, restrict car use, or even slap on environmentally-related taxes. But such fire-fighting is clearly not enough. Better engine technology will help, but hoping that it will swoop in and save the day is like waiting for Godot. Serious global steps are needed. The Environmentally Sustainable Transport (EST) guidelines, adopted by the OECD’s environment ministers in 2001, are one contribution (see box, page 46), though even they have had implementation challenges.Part of the problem is separating out travel, mobility and communications from transport itself. What was mostly new to the 20th century was not actual mobility, but mechanised transport by road and air. Steam trains revolutionised land travel in the 19th century, but their effect on mobility was as nothing compared with the advent of the automobile, truck and aeroplane. Over the 20th century, the motorised movement of people and goods increased more than one hundredfold, while the total human population increased fourfold. Even locally, road travel rose, while walking and bicycling fell. Only in poor countries is travel still done mostly on foot and bicycle, with an average of some 3,000 km per person per year. By comparison, the average American travels almost 30,000 km a year, mostly by car. Although freight and trade have also driven up mechanised transport, most vehicles are for personal use. In the US, which accounts for nearly a third of all the world’s mechanised road vehicles, some 90% of them are for personal transport. In fact, there are more personal vehicles in the US than commercial vehicles in the rest of the world combined.The total world fleet of road vehicles currently grows at about twice the rate of population growth. And it is likely to grow fastest in future in countries like China, Brazil and India, whose combined total fleet is about a fifth that of North America and a third that of Western Europe. In fact, the worsening trend in transport problems will affect developing countries most of all in the next few years.Car-nundrumIf car ownership worldwide were at the same level as in OECD countries, there would be some three billion cars on the world’s roads, rather than the current 540 million. The higher figure is a distant prospect, but the number of vehicles in circulation will remain a determining factor for environmental policy and resource use. The average distance travelled per car in OECD countries has stabilised in recent years, but this stability, even combined with better fuel efficiency and emissions control, has been more than offset by the sharp growth in fleet size and vehicle use.Fuel type is also important. In particular, consumption of diesel fuel is increasing at a higher rate than consumption of petrol, with a 4.6% annual rise from 1985 to 1995, compared with just 1.8% for petrol. The trouble is that while diesel engines are more fuel-efficient than petrol engines, with lower CO2 emissions per kilometre, they produce more breathable particulates, like ultrafine carbon, and chemicals like nitrogen oxide. Furthermore, worldwide use of diesel fuel is expected to increase, particularly as road freight traffic rises.Transport’s environmental performance has been poor, yet, realistically, mobility will continue: who would want otherwise? Whether by emphasising technology, innovation, taxation or regulation, achieving the decoupling of mechanised transport will be a hard, though necessary, challenge.Altitude atmosphericsThe atmospheric effects are foremost in public minds. One obvious concern is the emission of greenhouse gases. Emissions of CO2 from the burning of fossil fuels increased by a factor of seven during the 20th century, resulting in an increase of about a third in atmospheric CO2 levels. Transport directly contributes about 20% of these CO2 emissions worldwide, and close to 30% in OECD countries. These rates would be much higher in each case if emissions from vehicle manufacture, road construction and disposal were included. Then there is the methane released during petroleum extraction and nitrous oxide (N2O) in vehicle exhaust gases.Air transport adds to the problem. All those artistically criss-crossed jet clouds high in the blue sky have an “altitude effect”. At about 10 kilometres up, where commercial aircraft fly, the nitrogen oxides in the exhaust gases appear to be especially effective – two to four times more than on the ground – in facilitating the formation of ozone, a potent greenhouse gas. Aviation accounts for about 10% of motorised person-kilometres worldwide, and for less than 1% of freight movement, but this altitude effect may be responsible for about a quarter of transport’s contribution to climate change. Aviation is the fastest growing mode for the movement of both freight and people, so its global warming effect may exceed that of trucks or cars by 2030.Transport also generates a range of air pollutants (car exhaust contains some 500 compounds) that can damage health and the environment. Carbon monoxide (CO), volatile organic compounds (VOCs) and nitrogen oxides (NOx) are the most serious. CO exacerbates cardiovascular disease and causes neural damage, VOCs are carcinogenic and NOx cause respiratory, ocular and cardiovascular problems. In OECD countries, emissions of all three are falling, thanks largely to catalytic converters in motor vehicles, but worldwide their emissions are expected to increase, reflecting rising car use and poorer technology in developing countries.When sunlight acts on NOx and VOCs the result is photochemical smog. Ground-level ozone is the main constituent of this nasty cocktail and transport is the main contributor. It harms almost all biological tissue, damaging plants and penetrating deep into the respiratory tracts of animals. Smog also contains ultrafine particulate matter, some carcinogenic, of which diesel engines are the main source. Little wonder that several government agencies in North America and Europe classify diesel exhaust as a carcinogen. In North America, smog is believed responsible for 10-20% of hospital admissions for respiratory complaints in the summer months.People in cities are vulnerable to these pollutants, but perhaps none more so than drivers themselves. In fact, many studies have found that pollution levels inside vehicles are much higher than ambient levels, and even higher than the levels to which nearby cyclists and pedestrians are exposed. Children may suffer more than many, in particular those being driven to and from school.Road killIf only the problems were just atmospheric. Unfortunately, polluted air is not the only source of transport-related health risks. Road injuries are a major public health issue, too. According to one Harvard study, road traffic injuries are the 10th leading cause of death worldwide – about a million a year, with about 85% of those in developing countries – and the ninth leading cause of disability-adjusted life years lost. Though car safety has improved over the years, 125,000 people die every year on the roads of OECD countries. That’s one road crash death every four minutes.Noise from the likes of jetliners and trucks is also a problem that is increasingly recognised as a health risk. Moderate automotive traffic at a distance of 30 metres rates about 50 decibels, heavier traffic about 70dB. The World Health Organization recommends less than 45dB for productive sleep. Continued exposure to noise levels above 65dB presents a serious health hazard and increases the risk of cardiovascular diseases and mortality; levels above 85dB cause hearing loss. Again, children and people that live near highways appear to be particularly vulnerable. But there are stress-related risks from noise too.Land markA car commercial on French television shows a man running around hugging and shaking hands with road workers as they lay out fresh tarmac. He thanks them, joyfully, for creating the road on which he plans to try out his new car. The message is unusual, because while people are often encouraged to love their cars, even personalise them, not so for our roads. In fact, it has become politically fashionable for many to oppose everything from road widening to new road development. Yet, the very cities and towns we live in would not exist without roads. Roads are responsible for some great engineering achievements, from viaducts to tunnels. To some, they are possessed of aesthetic qualities, evoking images of evasion and dreams of the open road. But they are far from innocent landscape features.Roads affect ecosystems, interfere with natural drainage and block species migration. Highways, ramps, car parks, but also train tracks and aircraft runways: all consume environmental capital.
Transport infrastructure, mainly roads, consumes about 40% of land in urban areas of the OECD (more in North America) and less than 10% in rural areas. The road network occupies 93% of the total area of land used for transport in the EU. Per passenger-kilometre travelled, railways require less than a third of the land taken by passenger cars, aviation even less.Surprisingly, perhaps, the length of the total road network per capita has changed little since 1975; indeed, it has fallen in several countries. However, surface area has risen sharply, since the extent of motorways,tollways and other restricted roads has increased dramatically. These wider roads require displacement of some 130 times more matter (land, concrete, gravel, sand, tar, etc.) than other roads.Sprawl is a related problem. In the US between 1982 and 1992, the amount of land dedicated to urban uses increased from 210,000 to 260,000 square kilometres, 70% faster than the growth rate of nearby populations in urban regions. A particular feature of sprawl is the predominance of the private motor car. More fuel is used for transport as people drive around more. And that usually means a high land-take in terms of multi-laned highways, bypasses, driveways and other roads.GuzzlersAbout 20% of worldwide energy use is for transport, 30% in OECD countries. Almost all transport is fuelled by oil, which accounts for about 60% of total energy use. Transport is the main user of oil, accounting for some 60% of the amount extracted. The rest goes to heating of buildings and the production of items such as asphalt, plastics, detergents, fertilisers and medicines.Not all of the oil consumed by transport is used for vehicle fuel, as some provides the energy for the production, maintenance and disposal of vehicles and infrastructure. Oil also goes into the plastics that form an increasing portion of vehicles, including, ironically, to reduce weight and improve vehicle efficiency. At odds with this, though, is the continuing tendency in some countries to buy larger, more powerful, cars, like Sports Utility Vehicles (SUVs), rather than smaller ones.That means using more materials in construction. In fact, production of vehicles and transport infrastructure accounts for some 40% of consumption of major materials, including cement, steel and aluminium. Ores are another non-renewable input. Some common metals like iron and copper are recycled, but recycling becomes increasingly difficult as more sophisticated alloys and blends are used. Better substitutes will no doubt be developed, but their acceptance will take time.The same goes for the development of alternative combustion fuels. There have been many false dawns and interesting experiments, but until a competitive alternative has emerged, hybrids offer a next best solution. Take diester, for instance; this is a mix of canola vegetable oil and diesel, which is being successfully used in public buses in several French towns. But even canola production can entail serious soil depletion.Transport economicsTransport’s huge toll on public health and the environment can be evaluated. One recent study for the International Union of Railways puts the direct cost of this toll at 8% of GDP for OECD Europe. This includes accidents, noise, climate and pollution. It does not include congestion costs and indirect costs such as fuel supply, production of vehicles, etc. These could add another two percentage points. Road transport and aviation are primarily responsible; rail traffic contributes less than 1% of the social cost burden. The economy suffers, yet the economic consequences of all this are probably underestimated; for one thing, disposal and decommissioning of vehicles and infrastructure are also usually overlooked.Can it go on? Probably not. Most of the trends are expected to worsen, certainly worldwide. Aviation activity, for instance, will rise faster than the other modes, perhaps as much as 600% more than in 1990. Trends like this put the long-term environmental sustainability of transport systems in serious doubt. Sooner or later, the market may react. But to reduce the costs, policymakers will have to take a lead and make it sooner. That means putting environmental and health criteria up-front. The EST guidelines can help to do this. Doing nothing is no longer an option.Peter Wiederkehr and Nadia CaidReferencesOECD (2000), “Environmentally Sustainable Transport: Futures, Strategies and Best Practices”, see www.oecd.org/env, under “documentation, best practices”.OECD (2002), Policy Instruments for Achieving Environmentally Sustainable Transport, OECD, Paris, forthcoming.INFRAS/IWW (2000), “External Costs of Transport (Accident, Environment and Congestion Costs) in Western Europe”, report to the International Union of Railways, Paris.OECD (2002), Strategies to Reduce Greenhouse Gas Emissions from Road Transport: Analytical Methods, OECD, Paris.OECD (2002), Key Issues for Transport beyond 2000, ECMT, Paris.© OECD Observer No. 233, August 2002