'Smarter choices' - so what's the evidence?

'Smarter choices' is a broad collection of different initiatives aimed at enabling people to choose improved standards of accessibility with less car use. Our 2004 report 'Smarter Choices: Changing the Way we Travel' was commissioned by the DfT to make an assessment of the evidence available on workplace and school travel plans, personalised travel planning, public transport information and marketing, travel awareness campaigns, car clubs and car sharing, teleworking, teleconferencing, and home shopping. The report is some 700 pages, in two volumes, of case studies, literature reviews, and synthesis. Since then there has been important newer work on residential and leisure travel plans, and initiatives on cycling and walking.

Previous reviews of evidence

Already by 2004 there had been seven previous evidence reviews, dating back to 1997. Allowing for differences in definition, six of those seven reviews had calculated that the maximum impact on total traffic levels would be a reduction of 10% to 15% nationally, and 15% to 20% (maybe 30%) in favourable local conditions. The seventh had calculated a smaller effect, about 5% at national level, which, on inspection, was because the researchers had assumed a lower level of implementation. The latter figure was used to inform DfT advice to the multi-modal studies in 2002. The reviews taken together cited some hundreds of specific studies, mostly from the 1990s, of which the most common were of workplace and school travel plans, which contributed about a third of the total effect, though this was highly variable. (Wide variation applies to all the averages cited here, which include cases with little or no effect as well as the best performing ones).

Workplace Travel Plans

A large case study literature had already accumulated by 2002. Subsequent new evidence on best practice in 20 organisations indicated an average reduction in car driver trips of 18%, equivalent to 14 fewer cars arriving per 100 staff. Similar figures had been found in the USA and Netherlands. In further research in seven areas, we found that about 16% of the 2.2 million employees in the areas worked for companies already engaged in travel plans. Results available from 28 workplaces also showed an average reduction of 18% in car driver trips.

School Travel Plans

Six reviews of evidence published between 2000 and 2003 found some reductions in car use of up to 50%, but mostly in the range 10% to 20%. We carried out further study in eight areas, detailed work in three areas, and had access to results from 23 areas generated by a parallel DfT project. The results suggested that local authorities might expect to achieve an average cut in school car use of 8-15% across all engaged schools, with substantial reductions at some schools (up to 50%), but with relatively little effect at others, particularly those where generating a travel plan document was not matched with subsequent travel initiatives.

Personalised Travel Planning

A small but growing number of specialist agencies conduct programmes of interviews and guidance aimed at the specific travel patterns of individuals and households. Reductions in car use of 2% to 15% had been reported in 17 applications, mostly in Australia and Germany, by the early 2000s. We added detailed information on three case studies, and reviewed several other newly emerging ones. Overall, there were typical reductions in car driver trips of 7% to 15% in urban areas, and less robust indications of 2% to 6% in rural areas. There has since been a very rapid growth of interest in this technique, and the three Sustainable Travel Towns have given it more attention than has been paid to other ‘smart’ measures. Hence provisional findings suggest that this will be their major contribution to the evidence base (rather than new information on travel plans, for example, which were a less significant part of their programmes). Our work will be finished soon.

There is not space in this summary to give a breakdown of the separate evidence of the effects of the other types of initiatives listed, but allowing for them our overall estimate was of a potential reduction in total traffic levels of around 11%. This was based on detailed examination of many real-life examples, showing a wide variation and robust, recurrent, evidence of average reductions in car use.

The 2004 study had some strong caveats about the scale and nature of commitment, which remain important. At a local and national level many ‘smarter’ staff were, and some still are, treated as supernumerary and not important career professionals. Benefits can be undermined if other policies tend to increase, rather than reduce, traffic. We envisaged a ten-year programme, and it is likely that shorter-term initiatives would result in less significant impacts.

There are still some important unresolved questions about ‘smarter choices’. It is sometimes assumed that effects will primarily be on short car trips, though this will in part be influenced by the policies chosen (school travel plans and teleshopping target shorter distance journeys than workplace travel plans and teleconferencing, for example). Our work on this continues, and the results, soon available, already look very interesting. It is not yet known whether the observed behaviour change from interventions such as personal travel planning is due to many people making small changes in their behaviour, or a few people making large changes, as, indeed, is also little understood in longer-established policies on road use and public transport. Skills in designing better interventions, whose impact is ratcheted up over time, are still developing. Evidence on all these questions is still accumulating.

All scientific evidence is contingent, context-specific, and subject to amendment. It is right that considerable effort should be put into experiments, trials, demonstration towns and cities, and rural areas also. They will very usefully enrich understanding and knowledge. But it would be a mistake to think that the evidence already available is of minor significance: the field is maturing much more quickly than many people realise, and the reported impacts are substantial.

From rudi.net