Road planning needs a new systems approach

Days after being re-elected in 1967, Brisbane Lord Mayor Clem Jones reaffirmed his commitment to building the major urban freeway network recommended by transport consultant Wilbur Smith. Lord Mayor Jones said that
“We also know the (Wilbur Smith) traffic plan has to be carried out otherwise the traffic situation will cost the people of this city millions of dollars.” [note 1]

By 1984, a government review of Brisbane road plans noted that the 1981 population predicted for the city by Wilbur Smith had been achieved but not in the locations forecast.

“The difference in population distribution has resulted in travel patterns also varying from those expected.” [note 2] These differences are not surprising considering that only a fraction of the Wilbur Smith freeway network was ever built.

Did Brisbane reach major gridlock by 1981 without these freeways? No. Across the metropolitan area, people adjusted their travel and location decisions and Brisbane continued to grow and prosper. The urban system adapted to the road infrastructure available.

Systems thinking versus linear modelling
Systems thinking in urban studies has been around since the 1960s. It’s self-evident that cities are made up of complex interdependencies rather than separate, discrete elements like individual arterial roads.

In any complex system, feedback processes operate to change the first round effects, either reducing or amplifying these effects. However, road infrastructure planning often relies on mathematical models that are unable to deal adequately with system feedbacks. Litman (2012) sees the models this way:
“Most do not accurately account for the tendency of traffic to maintain equilibrium (congestion causes travelers to shift time, route, mode and destination) and the effects of generated traffic that results from roadway capacity expansion, and so tend to exaggerate future congestion problems and the benefits that result if roadway capacity is expanded.” [note 3]

Forecast travel time savings and the travel time budget
As well as forecasting future traffic flows, traffic models also calculate future travel time savings for road users.

However, the calculated time savings need to be interpreted in the light of how much time people travel each day. It turns out that this ‘travel time budget’ (the average time spent travelling per person per day) is relatively constant.

Doonan (2009) notes that
“It is well documented that people tend to allocate a set amount of time (often said to be a daily average of 75 minutes) which they are content to spend travelling. Beyond this time, people tend to change their travel behaviours to defer trips and find new, more accessible destinations.” [note 4]

SEQ Household Travel Survey data [note 5] confirms that the travel time budget in SEQ has been quite stable over time – 64 minutes in 1992, 70 minutes in 2004, 72 minutes in 2007 and 65 minutes in 2009. [note 6]

In contrast, there were many changes in transport infrastructure and settlement patterns in the Brisbane region, particularly between 1992 and 2004. [note 7] The travel survey results above suggest that residents in the region adjusted to these changes in a way that changed the average travel time budget only marginally.

Implications of travel time budget constancy
Travel time budget constancy means that time savings in part of the transport network are, on average, almost entirely ‘spent’ in other parts of the network. In other words, on average, almost no time savings are used for non-travel purposes.

Manning (2004) describes the consequences of this as follows:
“If the time budget rule (constant travel time budget) applies, there are two serious consequences for assessing the benefits of congestion relief. The first is that, for passenger traffic out of paid time, though not for freight traffic or for public transport operating costs, time savings are a chimera. Instead, the benefit of faster transport is greater distance travelled, which means that the benefit of urban road construction is sprawl.” [note 8]

In fact, between 1992 and 2007, the average distance travelled per person per day in SEQ increased by about 25%.

Forecast travel time savings on a new road facility come from forecast increases in travel speed for those using that facility. Litman (2009) considers that
‘(t)he true value of changes in travel speed can be difficult to determine because people tend to have fixed travel time budgets, typically about 70 daily minutes or 8 hours weekly to personal travel. As a result, increased travel speeds tend to increase travel rather than save time. For example, if a highway or transit improvement increases travel speeds, commuters often accept longer distance commutes. As a result, the true benefits are increased mobility and improved location options, not time savings.” [note 9]

How forecast travel time savings influence project evaluation
Reductions in travel time for road users are generally considered to produce community benefits. As Metz (2008) puts it:
“The idea is simple: there are better things to do than travel, so if travel time could be reduced by improving the infrastructure, then there would be a quantifiable economic benefit to set against the cost of the investment.” [note 10]

These reductions (as calculated from the modelling process) are given a dollar value and included as a benefit in the cost benefit analysis (CBA) for the project. The dollar value of the forecast time savings often makes up most of the benefits claimed for the project. For both the Go Between bridge and the Airport Link, forecast time savings were about two-thirds of the claimed benefits. [note 11]

However, as Metz (2008) notes
“If travel time is conserved rather than saved (i.e. constant time budget), then there are implications for investment appraisal, modelling and policy as discussed above. In particular, standard CBA is not a reliable guide to the value of infrastructure investment and arguably should be abandoned.”

“Travel time savings are likely to arise as a transient phenomenon. It might be supposed that the possibility of saving time would be an important factor to be considered when the choice of a new travel option presents itself. But once the new route or mode becomes part of an established pattern of daily activity, the benefit may then be perceived as an improvement in access, rather than as a time saving. With the elapse of time (months or years), the improvement in the transport system allows further access to desired destinations, within the more or less constant time people allow themselves on average for travel.” [note 12]

Without travel time benefits, it is likely that few urban arterial road projects would achieve a positive Benefit Cost Ratio. [notes 13 & 14] That is, the costs would almost always exceed the calculated value of the benefits. This suggests that other criteria need to be used for evaluating these projects, in particular to what extent the project supports the achievement of broader planning objectives.

Implications for metropolitan planning
Gleeson et al (2004) note that
“(t)here is a national consensus on the need to address the car dependent, sprawling morphology of Australian capital cities.” [note 15]

The SEQ Regional Plan addresses this issue by focussing on compact settlement, particularly through Desired Regional Outcome 8 Compact Settlement.

In reality, at the individual project level, the evaluation methodology used for road projects is undermining the Regional Plan’s compact settlement objective by including forecast time savings as a project benefit. Perversely, this practice has not reduced travel time in the aggregate, but has encouraged longer trips. [note 16]

Historically, transport infrastructure has had a significant impact on settlement patterns in the Brisbane region, starting with the Brisbane to Ipswich railway in 1876. Heywood (2000) argues that, in some respects, the Wilbur Smith traffic plan of the 1960s
“exerted a stronger influence on the development of settlement form than did the (1965 Brisbane) Town Plan” [note 17]

Beard (1998) is concerned about the influence of transport infrastructure such as the late 1990s Pacific Motorway upgrade on settlement patterns, asserting that
“Where and how we provide transport infrastructure will profoundly influence the shape of our cities. The primary objective of transport infrastructure planning should be to positively influence the urban environment, not to satisfy forecast travel demand.” [note 18]

Brisbane City Council’s TransApex project [note 19] is a current example of building transport infrastructure to satisfy demand rather than to positively influence the urban environment.

In 2007, the Brisbane Lord Mayor – in an echo of what his predecessor said 40 years before – told a journalist that
“‘These (the TransApex projects) are vital pieces of infrastructure that the city can’t do without in years to come’. He says that congestion would cost Brisbane $9.3 billion a year by 2015 if nothing were done.” [note 20]

In contrast, Gleeson and Steele (2009) describe TransApex in this way
“the ‘crash through’ infrastructure development style of the TransApex project with its focus on facilitating trans-metropolitan travel and improving congestion and delays for motorists, is contradicting the State and council’s own commitment to sustainability and reducing car dependency. These are core strategic planning values outlined in key planning instruments at all levels of government. The crash through approach which increasingly resonates in infrastructure politics is starkly at odds with planning’s claim to value deliberation and sustainability.” [note 21]

Road planning needs a new systems approach
Ignoring the system effects reflected in the constancy of travel time budgets has worked against metropolitan planning’s key concerns of compact settlement and sustainability, and left the community with very large debts that will be a drain on public sector budgets for years to come. [note 22]

Simplistic assessment methods inherited from a time when the need for urban road infrastructure was considered self-evident are no longer good enough.

Community demands for sustainability and value for money must surely mean that these outmoded assessment methods have to be discarded, and system effects taken much more seriously. All projects should be evaluated for their contribution to creating a more sustainable city, not on how well they satisfy forecast travel demand.

1. Brisbane Lord Mayor Clem Jones, Courier Mail, 24 April 1967.
2. Policy Committee for Brisbane Region Transport Planning (1984), ‘Brisbane’s Major Road System, A statement of policy and objectives’.
3. Litman, Todd (2012), ‘Online TDM Encyclopedia’, Victoria Transport Policy Institute.
4. Doonan, Kellie (2009), ‘Setting the Transport Scene’, Queensland Department of Transport and Main Roads.
5. ‘SEQ Household Travel Survey Data (2011)’, Queensland Department of Transport and Main Roads.
6. Sampling errors may well account for some of the variation. The Global Financial Crisis may also have affected the 2009 data.
7. New road infrastructure included: Gateway Motorway upgrade 1995, Gateway Motorway extension to Logan Motorway 1997, Pacific Motorway upgrade to Nerang 2000, Inner City Bypass 2002, and Bruce Highway upgrade north of Gateway Motorway 2002. The Pacific Motorway upgrade in particular stimulated residential growth in northern Gold Coast areas such as Pacific Pines and Ormeau.
8. Manning, Ian (2006), Victorian Competition and Efficiency Commission Inquiry into Managing Transport Congestion – Submission by Dr Ian Manning.$File/Submission%20DR%20100%20-%20Ian%20Manning.pdf
9. Litman, Todd (2009), ‘Transport Cost and Benefit Analysis’, Victoria Transport Policy Institute.
10. Metz, D (2008), ‘The Myth of Travel Time Savings’, Transport Reviews.
11. See GHD (2006), ‘Hale Street Link Impact Assessment Statement’ and SKM/Connell Wagner (2006), ‘Airport Link Environmental Impact Statement’ Vol 3.
12. Metz, D (2008), ‘The Myth of Travel Time Savings’, Transport Reviews.
13. According to the Environmental Impact Statement for the Airport Link project, the benefit-cost ratio is only 1.1 even with ‘time savings’ for private motorists (i.e. not in work time) accounting for half the claimed benefits.
14. For a discussion of more fundamental problems with Cost Benefit Analysis see Ackerman, Frank (2008) ‘Critique of Cost-Benefit Analysis, and Alternative Approaches to Decision-Making’.
15. Gleeson, B, Darbas, T, Johnson, L and Lawson, S (2004) ‘What is Metropolitan Planning?’ Urban Research Program, Griffith University.
16. The Queensland Treasury’s ‘Project Assurance Framework’ generally requires that a CBA be undertaken in assessing State-funded projects, thereby helping to entrench this perverse outcome.
17. Phil Heywood (2000) ‘The Planning and Development of Brisbane’s Urban Form and Structure’ Brisbane City Plan: A City Strategy, Background Discussion Paper No 7, Brisbane City Council.
18. Beard, Colin (1998), ‘Government sponsorship of urban sprawl in South-East Queensland’. Transport Engineering in Australia.
19. Projects under the TransApex banner are the Clem 7 tunnel, the Airport Link, the Go Between bridge, Legacy Way and the East West Link see
20. Brisbane Lord Mayor Campbell Newman, Australian Financial Review, 17 August 2007.
21. Gleeson, B and Steele, W (2009) ‘The Bellwether Zone? Planning Infrastructure in South-East Queensland’, Urban Research Program, Griffith University.
22. Brisbane City Council budget documents show a commitment to spend more than $2 billion on just three of the TransApex projects – at least $500 million spent on the Clem 7 tunnel, $320 million spent on the Go Between Bridge and a commitment of $1.3 billion for the future Legacy Way tunnel.


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