The future of transport appraisal
28 September 2018

The future of transport appraisal

By Boris Johansson, Toby Cuthbertson and Duncan Irons, SYSTRA

The future, as the saying goes, is not what it used to be. The old certainties that have guided transport planning for the last thirty years or more have been rapidly worn away by changing political priorities, technological developments and consumer trends leaving the forecaster with less and less solid ground to stand on. There has never been a crystal ball, but today it can seem more like gazing into a brick wall. So, what is to be done?

It’s not the first time appraisers have had to adjust to major changes, of course. But this is of a different order of magnitude. In the recent past we have had to adapt to many significant changes that have affected the behaviour of models and the accuracy of forecasts, but these have tended to be refinements that left the fundamentals unchanged. Vehicles have changed a lot in the last fifty years but they have continued to be used in more or less the same way by people travelling in the same patterns for the same sorts of reasons, just a little quicker or more comfortably.

Behaviour, in other words, has remained relatively consistent and that consistency has enabled us to build models that can be adjusted with at least some confidence to reflect relatively gradual and predictable change. But new technology is disrupting long established patterns. Services such as Uber are breaking down the public/private divide and app-based connectivity encourages a highly integrated, flexible and contingent approach to consumer travel planning that responds in real time to changing local conditions and is, therefore, by its nature unpredictable. And this is just the start of the tech revolution. Autonomous vehicles are becoming a realistic prospect that will potentially change private car use out of all recognition and in turn trigger changes in behaviour and demand that we can now only vaguely imagine. Accurate appraisal outcomes will certainly become ever more challenging.

At the same time public policy demands have been changing fast too. The days of ‘less congestion, more traffic faster’ are now behind us and the industry has responded well to new regeneration and sustainability agendas which prioritise place-making and environmental protection. But the pressure to develop schemes that actively promote economic and social growth for a new generation that make very different decisions from the past is only going to get more intense. Evaluation, meanwhile, grows ever more stringent in the age of austerity. New objectives for a less predictable future will be judged more harshly: by any standard, this is a challenge.

But it is not an unsurmountable one. To meet it, we will have to step forward and embrace uncertainty. Instead of providing a detailed, highly analysed ‘correct’ solution, we can instead work to a scenario planning model along with policy makers from the onset. In this way we take a broad view of possible outcomes and instead of just asking - what is most likely to happen, we ask what is most desirable? Policy makers are then encouraged to move away from the natural question of ‘how do we address the future demand we think is coming’ and to ask instead: ‘what is the future you want to aim for, from a range of plausible scenarios?’

We also need to evolve the culture of forecasting for appraisal. Taking the scenario-based approach, which acknowledges different plausible outcomes is one way to enable decision-makers to consider the drivers of change.

The technologies that are disrupting transport behaviour and appraisal are also tools that can be adapted to shape it as part of a broad policy agenda aimed at creating live-able, economically thriving places.

The danger is that, faced with daunting complexity of analysis, we retreat back to our comfort zone, to simpler models and ideas that have served us well in the past. There is a lot at stake after all, our models help form the basis of expensive, disruptive and politically sensitive decisions.

While any forecast could be debated to be “wrong”, albeit for a range of reasons, as transport planners we can’t ignore the potential political and commercial risks that this carries. The wider point here is that, when appraisal takes a limited view of the future based on a subjective “most likely” basis, then this inevitably carries a risk.

Yet, we have to make sure that we don’t repeat the mistakes of the past by clinging to tools that have served us well so often but which were designed for a different world. We can no longer simply predict change, we have to be drivers of it.

In our dynamic world, we need to look far and wide for clues to understanding travel behaviour. Going forward, policy makers and practitioners alike will need to look outside their own national or regional experiences. As well as being open about assumptions on passenger valuations, impacts of demand drivers and impacts of new technology changes so that processes can be dynamically updated as understanding gets better. Importantly, the industry is up for the challenge.

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