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Environmental impacts of Australia's transport system
The contribution of GHG from Australia's energy sector, which includes transport emissions, was 372 Mt (megatonnes) of carbon dioxide equivalents (CO2-e) or 69.5% of Australia's net national emissions in 2000 (table S23.2). Transport contributed 14.3% (76 Mt) of net national emissions, an increase of 3.3% of 1999 levels and 24.2% of 1990 levels. In 2000, road transport contributed 90.2% (69 Mt CO2-e) of transport emissions or 12.9% of net national emissions (table S23.3). Cars contributed 62.4% (43 Mt CO2-e) of transport emissions or 8% of the net national emissions. Trucks and light commercial vehicles contributed 35.3% (24 Mt CO2-e) or 6.5% of the net national emissions.
Overall, Australia's emissions per urban passenger kilometre travelled have increased by 7.5% between 1990 and 1999 (1999 figures are the latest reliable figures). Emissions per non-urban passenger kilometre travelled have fallen by 9.7% in the same period, and emissions per tonne-kilometre of freight have decreased by 9.5% since 1991. The volumes of travel have increased in this time as well, leading to a net increase in emissions (AGO 2002).
Emissions by transport mode
Passenger cars contributed 56.3% (43 Mt CO2-e) of transport emissions, an increase of 22.2% over 1990 levels (table S23.3). The number of vehicles on Australia's roads and number of kilometres travelled have increased, and on-road fuel efficiency has also increased. Liquid petroleum gas, a less polluting source of fuel, has increased its usage level by more than double since 1990.
Truck emissions increased by 33.9% between 1990 and 2000, to 15 Mt. The fuel efficiency of trucks fell by 4% over the same time period (AGO 2002). Light commercial vehicles emissions increased by 31.2% in this period despite an increase in fuel efficiency of 2%. Bus emissions increased by 17.9%.
Emissions from aircraft have increased by an average of 5.4% each year since 1990, due to an increase in domestic air passengers and freight. Coastal shipping emissions were 1.5 Mt in 2000 (2% of transport emissions).
Types of transport emissions
Most transport emissions are CO2, with small amounts of nitrous oxide and methane (table S23.4). Nitrous oxide emissions have doubled in proportion to other gases, from 2.7% of transport emissions in 1990 to 5.4% in 2000. This has been attributed to the increase in vehicles with catalytic converters and other pollution prevention technology. Three-way catalytic converters reduce emissions, but produce 12% more methane and 154% more nitrous oxide per kilometre than cars with two-way converters or those without pollution control devices. Catalytic converters have been fitted to new cars since 1987, and aim to reduce the contribution of car emissions to air pollution (AGO 2002). For more detail on the environmental impact of emissions, see Environment.
Impacts of road transport
Use of road transport
Of the Australian vehicle fleet, passenger vehicles constituted 9.7 million (80%) of the 12.2 million vehicles on Australian roads during the 12 months ended 31 October 2000. Light commercial vehicles were the second most populous vehicle type, with just under 1.7 million vehicles (14%). During this period, the total fuel consumed by Australian vehicles amounted to 24,926 million litres, passenger vehicles accounting for 16,190 million litres (65%). Total kilometres travelled in this time were 180,782 million. These measures all rose in the three years to 31 October 2000 and provide an indication of the growth of the road transport task in Australia (ABS 2001b).
Road transport's fuel efficiency
In 2000 the average rate of fuel consumption of passenger cars was the second lowest (at an average of 11.7 L/100 km travelled) after motorcycles (6 L/100 km). The vehicle type with the highest average fuel use was articulated trucks, consuming 52.3 L/100 km. Energy efficiency, while increasing slightly, has been offset by increases in vehicle weights and power outputs. For example, engines have become more efficient, but are bigger and more powerful, leading to only slightly lower fuel use levels per car (ABS 2001b).
The average age of passenger vehicles, the largest component of the vehicle fleet, was 10.1 years at 31 March 2001. Some 44% of the passenger vehicle fleet was 13 years or older and 24% was 8 years or older. The rate of fuel consumption of these vehicles is important.
The Bureau of Transport and Regional Economics has recently published figures on both fuel consumption and engine performance of Australia's passenger vehicle fleet, from the mid 1970s. Trends indicate that both are decreasing, but only slightly, and less than could be expected with the current advance in efficiencies and technology.
Car manufacturers are responding to buyers' demands for bigger, more powerful cars, and as a result, fuel efficiencies and fuel consumption have decreased by slightly more than 10% (BTRE 2002a). Several manufacturers are now offering dedicated LPG fuel vehicles and hybrid petrol and electric vehicles with the aim of reducing the environmental impacts of motor vehicle use. A major initiative of the Australian Greenhouse Office is to encourage the purchase of fuel efficient vehicles by placing a fuel consumption sticker on new cars, showing the on-road fuel efficiencies. Some 24% of Australian households purchased a motor vehicle in the 12 months to March 2000. The environmental impact of the car was the least important factor in households' decision to buy a car (rated most important by only 3% of households), while the cost of the motor vehicle was the major factor (rated as such by 53% of households) (ABS 2000).
Minimising road transport travel demand and vehicle kilometres travelled
Reducing vehicle kilometres travelled (VKT) and managing the demand for transport are key areas for minimising the environmental impact of transport. Overall VKT has increased over time. Passenger vehicles contribute the bulk of VKT (Newton et al. 2001). Initiatives to minimise VKT include programs to reduce the demand for transport, maximise vehicle occupancy rates and maximise uses of public transport services which will reduce fuel use, emissions and congestion. Private vehicles are the most common form of transport to work or school, with 76% of households driving to work or school in 2000. In contrast, 6% walked or cycled, and 12% took public transport. Only 2% took public transport for environmental reasons (ABS 2000).
Road transport's impacts on biodiversity and wildlife
Although only limited research has been carried out, transport is thought to impact on biodiversity and wildlife in several ways. Road transport is responsible for a large number of deaths and injuries to animals each year, although the numbers are difficult to obtain. WIRES (NSW Wildlife Information & Rescue Service) estimates that 3,400 native animals are killed every day on Australian roads. Table S23.5 shows deaths or injuries to native wildlife in New South Wales in 1993-94. Other estimates of roadkill suggest that up to 5.5 million frogs and reptiles are killed on sealed Australian roads each year (Mackey et al. 1998).
Roads themselves impact upon biodiversity and wildlife. Roads are a barrier to movements by some native species, and can isolate species and alter the interactions of wildlife populations as a result. Roads enhance the dispersal and movement of weeds and feral predators. In the same way that species can travel unknowingly in ballast water, seeds and spores can travel on vehicles in mud deposits and colonise new areas, while feral animals (such as cats, dogs and foxes) use the roads as a corridor to move into areas previously unaffected by the feral species (Mackey et al. 1998). Road and track construction can also impact locally on the natural environment, as it can lead to changes in an area's water flows and increase sedimentation in local waterways. Off-road vehicles have an effect on local areas, through increased erosion levels, frightened wildlife, devegetation of adjacent areas and increased access to remote areas, thereby decreasing the wilderness values of areas (ABS 1997).
Road transport's impacts on urban stormwater
Urban sprawl in cities increases the amount of impervious areas in a catchment area. This leads to increased run-off into local waterways, as less water soaks into the ground. Increased run-off has been linked to the increase in pollution levels of local waterways. Vehicles contribute to this pollution through the buildup of deposits from emissions and from mechanical parts wearing out. Tyres and brake linings (from brake pads etc.) are a major source of heavy metals in urban environments, as are petrol and oil deposits. Cars deposit small amounts of these contaminants as they travel, and as more cars travel the deposits build up. When it rains, the deposits can be washed into the stormwater systems, eventually polluting waterways, estuaries and beaches, where the stormwater is released (ABS 1997).
Road transport's impacts on the urban environment
The quality and distribution of urban transport systems has a major bearing on the livability of urban environments. The private car maintains its place as the dominant form of transport for personal travel (ABS 2000). Cars have had a profound impact on the structure of urban areas, leading to the concept of car-centered urban sprawl. Dispersed cities put greater strain on infrastructure such as water supply and sewerage systems and lead to stalled traffic, excessive noise and polluted air (Brown 2001). Congestion is another product of urban dependence on the private vehicle. The costs of congestion are considerable, as fuel, time and other resources are wasted (Newton et al. 2001). Urban areas have become more congested as more automobiles are being driven and mobility has decreased.
Impacts of marine transport
Australia's coastal environment is threatened by our heavy dependence on international and coastal shipping to transport goods to, from and around the country.
Oil spills cause a significant impact on marine environments. Fortunately, Australia has not suffered a catastrophic oil spill as other countries have. Australia has, however, experienced several spills that have impacted upon the local environment. Some of the major spills are shown in table S23.6. These spills have been the result of various circumstances and have had significantly different impacts. Some spills have been a result of extreme weather forcing vessels, such as the Korean Star, to run aground and leak fuel and oil, while other ships have been damaged in ports, allowing the subsequent spill to be successfully contained to minimise the impacts. Several spills occurred in open water, and resulted in the loss of wildlife and severely damaged local environments, such as the spill from the Arthur Phillip, which killed or seriously affected 200 fairy penguins. Other spills have been the result of the transfer of cargoes, such as between the Laura D'Amato and the Mobil Refinery.
Ballast water, bilge water, sewage, wastes from vessel maintenance and anti-fouling paints cause some of the other environmental impacts associated with shipping. Ballast water, used to stabilise empty ships when travelling to pick up cargoes, presents the potential for major environmental impact. Ballast water is discharged when loading, and may contain invasive non-native organisms that can impact on local environments (Newton et al. 2001). Ballast water can introduce non-native and environmentally harmful organisms, diseases, toxins and parasites that affect humans and ecosystems. At least 55 species of fish and invertebrates and a number of seaweeds have been introduced through ballast water discharge (ABS 1997). Anti-fouling paints are used on vessels to stop organisms growing on hulls. The paints contain toxic chemicals that leach into the surrounding water, polluting harbours and waterways.
ABS (Australian Bureau of Statistics) 1997, Australian Transport and the Environment (4605.0).
ABS 2000, Environmental Issues: People's Views and Practices (4602.0).
ABS 2001a, Energy and Greenhouse Gas Emissions Accounts. Australia (4604.0).
ABS 2001b, Survey of Motor Vehicle Use, Australia (9208.0).
AGO (Australian Greenhouse Office) 2000, National Greenhouse Gas Inventory 1998, Australian Greenhouse Office, at http://www.greenhouse.gov.au.
AGO 2001, National Greenhouse Gas Inventory 1999, Australian Greenhouse Office, at http://www.greenhouse.gov.au.
AGO 2002, National Greenhouse Gas Inventory 2000, Australian Greenhouse Office, at http://www.greenhouse.gov.au.
AMSA (Australian Maritime Safety Association) 2002, Major Oil Spills, at http://www.amsa.gov.au.
Brown Lester R 2001, Eco-economy: building an economy for the Earth, WW Norton and Co., New York.
BTRE (Bureau of Transport and Regional Economics) 2002a, Australian Transport Statistics 2002, at http://www.btre.gov.au.
BTRE 2002b, Fuel Consumption by New Passenger Vehicles in Australia, Information Sheet 18, at http://www.btre.gov.au.
Mackey BG, Lesslie RG, Lindenmayer DB, Nix HA & Incoll RD 1998, The role of wilderness in Nature Conservation, a report to the Australian and World Heritage Group, Environment Australia, July 1998.
Newton PW, Baum S, Bhatia K, Brown SK, Cameron AS, Foran B, Grant T, Mak SL, Memmott PC, Mitchell VG, Neate KL, Pears A, Smith N, Stimson RJ, Tucker SN & Yencken D 2001, 'Human Settlements', Australia State of the Environment Report 2001 (Theme Report), CSIRO Publishing on behalf of the Department of the Environment and Heritage, Canberra.
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