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BITRE | Working paper 74


Eventually people are spending as much time on daily travel as they are willing to

commit—and are loathe to spend any more of limited time budgets on even more

travel, even if average income levels continue to increase. So growth in per capita

personal travel is likely to be lower in the future than for the long term historical trend

(BTRE 2006b, p. 50).

This conclusion is qualified by the observation that freight movement trends are not

expected to follow this pattern but ‘tonne kilometres performed per capita are still

growing quite strongly ... there is no saturating tendency evident yet’ (BTRE 2006b).

However, since freight vehicles tend to involve a greater proportion of travel outside

of the traditional peak periods (BTRE 2006b, p. 78), this growth will not have the same

impact on congestion costs as would growth in passenger motor vehicles.

Impact of network capacity increase

Clearly, estimates of future congestion costs will be the outcome of the combination

of traffic growth and the expected increase in network capacity. The most recent

projections of future congestion in Australia concluded that:

The [linear] growth rate means that the same absolute volume of traffic (in PCU terms)

will be added to our capital city roads in the next 15 years as was added in the past 15

(BTRE 2006b, p. 45).

The widely-quoted figure for Australia of congestion costs of $30 billion by 2015 is

qualified by the statement that ‘these projections do not take account of any measures

that might be taken to avert these kind of results, or of any major road developments

since 1995’ (BTCE 1999).

The figures in BTCE (1999) are derived from the congestion costs estimates in BTCE

(1996a). By necessity, this publication used data sets on traffic flows between the late

1980s to those collected in 1993. Hence, the impact of major improvements made to

the network as far back as 1992 (for instance, the Sydney Harbour Tunnel) could not

to be incorporated in the estimates (BTCE 1996a, p. 2).

An allowance was made for network expansion of 5 per cent per annum. Whether

the congestion cost estimates fully capture the impact of many of the recent

improvements in the network is unlikely. Table B3 lists the major projects (mainly

improvements in the radial network, ring roads and ‘internal bypasses’) in New South

Wales and Victoria that would be expected to have eased urban traffic congestion

since the original estimates were undertaken. 89

These network improvements (introducing major new arteries and relieving critical

pinch-points) have meant that some traffic demand growth has been accommodated

in the major cities without a notable increase in travel times—in some cases a decline

in travel times. However, this may not provide a comprehensive view of urban travel


Austroads (an association of Australian and New Zealand road transport and traffic

authorities) compile a number of congestion indicators, including travel times in the

capital cities: more technically, the ‘weighted aggregate speed on a representative

sample of arterial roads and freeways in major cities’. While as a congestion indicator

this measure has limitations, the indicators suggest that travel times during the

morning peak on key roads in most major capital cities have not increased significantly

over the past five years—see Figure B4.

89. Although, there is some controversy about whether the Cross City Tunnel has led to a reduction or an increase in


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