Increased traffic


Traffic is greatly affected by pressures from population and economic growth, unless there is a significant decline in car use per person. Any associated traffic increase is, in turn, its own pressure on urban amenity and livability. This section provides some broad-level historical and projected transport trends to provide context for the pressures associated with traffic trends. A more comprehensive discussion of recent state and trends of urban transport is provided in Transport in State and trends of the built environment.

Australia’s cities generally show higher private car use relative to public transport use than overseas cities (Armstrong et al. 2015). Total passenger travel in Australian cities has grown almost 10-fold during the past 70 years, with private road vehicles currently accounting for 87 per cent of the aggregate urban passenger task. However, per-person reductions in car use have begun (see Figure BLT28). Under currently expected patterns of metropolitan population growth, a steady increase in aggregate urban traffic is likely in the next 15 years, with total vehicle-kilometres2 travelled forecast to increase by around 2 per cent per year to 2030 (BITRE 2014). However, there are significant questions about the impact of continuing declines in per-capita car use, urban infill, Uber, public transport growth, autonomous vehicles and smart phone–related car sharing.

Outside the major cities, in the ‘inner-regional’ communities that surround Australian cities, almost all the inner-regional population of more than 4 million relies entirely on the car for transport (Armstrong et al. 2015).

Transport types

Figure BLT5 shows the proportion of transport types used in our cities, including historical trends and scenario projections.

Public transport accounts for a significant proportion of city transport—for example, nearly one-third (31 per cent) of Sydney commuters use public transport as their main mode of transport to work or study (see Public transport). Urban rail provides a major share of transport into the central business districts of the larger cities. Global trends of increased growth in public transport are also found in Australian cities. All Australian capitals are predicting and planning for an increase in public transport compared with private vehicle use. Demand for public transport is set to rise by an average of 89 per cent across all capital cities by 2031. This may mean that more services will experience ‘crush loadings’, where peak demand exceeds capacity, unless peak-period passenger loads are managed and capacity is increased (Infrastructure Australia 2015). However, the bulk of urban passenger travel will still be on the road system, largely by private motor vehicles, for the foreseeable future (BITRE 2015b).

Most intra-urban freight is moved by road—intra-urban freight represented 59 billion tonne-kilometres (transport of 1 tonne by road for 1 kilometre) in 2015, and is growing at around 3 per cent per year.

Impact of traffic increases

Given the size and structure of large parts of Australia’s cities, motor vehicle travel is essential if city residents are to access jobs and services. However, such travel also comes at a cost. For residents, there are the ongoing costs of owning and operating a motor vehicle, and the time taken to travel. This is a particular burden on residents who have few transport alternatives and are required to travel long distances. In addition, congestion, productivity and environmental costs are all rising. Australia is one of the world’s highest per-person emitters of greenhouse gases. Transport emissions are particularly high and continuing to grow (Armstrong et al. 2015). Increasingly, motor vehicle travel is becoming a strain for the functioning of our cities and their economies.

Future increases in Australian capital-city traffic volumes are expected to lead to increasing aggregate social costs because of road network delays, at least in the medium term (BITRE 2015b). Severe bottlenecks and capacity constraints along critical road arteries and rail corridors are already causing delays, resulting in lengthy travel times for commuters and lost productivity (Infrastructure Australia 2016).

The ‘avoidable’ cost of congestion (where the benefits to road users of some travel in congested conditions are less than the costs imposed on other road users and the wider community) for Australian capital cities is estimated to be around $16.5 billion in 2014–15, having grown from about $12.8 billion in 2010 (Figure BLT6). This total comprises approximately $6 billion in private time costs, $8 billion in business time costs, $1.5 billion in extra vehicle operating costs and $1 billion in additional air pollution costs (BITRE 2015b).

Business-as-usual projections of the costs of metropolitan congestion rise to around $30 billion by 2030—the various modelling scenarios conducted give aggregate 2030 results of between $27.7 billion and $37.3 billion, depending on the chosen assumptions (BITRE 2015b).

Such modelling cannot be certain because it is subject to many social and technical factors. Hence, the exact extent of congestion increases—and consequent implications for mobility and amenity in our cities—will depend on a range of social and technical factors. Australian cities, like all developed cities, are now decoupling their economic growth per capita from their growth in car use per capita (Newman & Kenworthy 2015). Traffic and congestion management requires an analysis of a range of potential options, including suitable pricing measures and emerging technologies. (See Traffic in Effectiveness of management of the built environment for a discussion of how traffic is being managed and how it will be managed in the future.)

Coleman S (2016). Built environment: Increased traffic. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra,, DOI 10.4226/94/58b65a5037ed8