Beyond the travel time savings paradigm for project appraisal

The experience shows that state-of-the-art practices on planning and project appraisal often result in contradictory conclusions when applied to sustainable mobility policies, particularly at the urban scale. Benefits associated with faster transport are central according to many standard cost-benefit guidelines, therefore providing higher economic return than improving other social and environmental aspects of projects, which paradoxically have increasing social importance in more mature and advanced societies. Therefore, the time trap of standard cost-benefit analysis (CBA) could support projects transferring public urban space from pedestrians back to car traffic, just because drivers could benefit from a few seconds of time savings.

This fact results in great misunderstandings when CBA is used in public hearings and deliberations. Mobility and transport policies at both urban and interurban scales have today in Europe a comprehensive set of goals such as the improvement of accessibility, sustainability, liveability and affordability, well beyond achieving faster travel. The emergence of virtual technologies as well as the changing values of new generations makes evident the need to reconsider.

The claim for a paradigm shift in transport planning is not new. As early as the 1960s there were a number of relevant expert opinions challenging faster travel as the overwhelming criteria for transport planning – like the well-known “Traffic in Towns” report by Collin Buchannan (1964).

Arguments for focusing on enhanced accessibility vis-à-vis travel-time savings are rooted in time-budget theory (Zahavi and Talvitie, 1980; Tanner, 1981). Despite rapid increases in average travel speed, people continue to invest roughly the same amount of time to move about a city, on average an hour per day. This daily time budget has held remarkably constant over time, from ancient Rome to the walking cities of 15th century Europe to the streetcar suburbs of the early 20th century and freeway-laced cities of today. Time budgets are seemingly an anthropological constant, as if people are genetically pre-disposed to spend a fixed amount of time during their lives moving about their surroundings.

For environmental costs, the strongest argument against the simple willingness-to-pay approach is that individuals often do not correctly perceive the costs of environmental impacts; for instance, that of air pollution on health, crops and buildings. Noise is often valued based on the house price approach whereby the willingness-to-pay of residents to reduce noise nuisance is estimated from differentials in house prices between quiet and noisy environments, other things being equal (Nellthorp, Bristow and Day, 2007). Research is also taking place using the willingness-to pay-approach to examine townscape and landscape, although the difficulty of classifying different landscapes in terms of their amenity value is a considerable barrier; unlike noise, landscape value is not easily measured.

All in all, since the economic theory of the valuation of time was first worked out in the 1960s, the practical application of the value of time concept in the social appraisal of projects has been controversial. Mackie, et al. (2001) synthesised some key questions related to the issue in several studies over the last decades;

• Should time savings be valued at all? Atkins (1984) suggests not.
• Should behavioural values derived from individual willingness-to-pay be carried through and adjusted into evaluation? Sugden (1999) suggests so. If not, how should they be adjusted?
• Should the social value per minute vary with the size or the sign of the time saving? Welch and Williams (1998) propose so.
• Should the value of time be assumed to increase proportionately with income or less than proportionately? A published report by Accent/Hague (1999) suggests that for the UK, an income elasticity of the value of travel time savings of 0.5 is more consistent with the evidence than an income elasticity of unity.

Moving beyond faster travel as a dominant decision-making paradigm is not to say that saving time to millions of people commuting daily by public transport is not an important welfare gain; or that reducing door-to-door travel time for intercity rail travellers or for air business trips are relevant policy goals. We still believe that saving time remains an important indication of transport efficiency. But the concept of “value of time” needs to be reconsidered to better reflect the social and technological developing trends, and should be complemented with other concepts such as “value of access”. Values assigned to social and ecological factors also have to be reconsidered in the CBA framework.

There are a number of research initiatives at the local, national, European and international scale with these aims, but still much needs to be done for a real change.