New challenges in city transport modelling

Transport modellers are ill-equipped to understand how changes in urban lifestyles and technology will affect peoples’ travel behaviour, a transport modelling expert told Modelling World. 

Delivering the keynote address, Professor John Polak said the modelling profession had almost “zero capability” to model the response of citizens to new collaborative consumption lifestyles, such as car clubs, car sharing, and other peer-to-peer arrangements.

Polak, chair of the Centre for Transport Studies at Imperial College London, identified this as one of four challenges for modelling what he called ‘smart cities’. The others were:

• the effect of different information products and services on travel choices;

• the relationship between physical and virtual activities, for instance, internet shopping; and

• the inter-relationship between transport and other city systems and processes, for instance, interactions between transport, land-use and labour markets.

Polak said the uncertainties about future developments in society were enormous and there was a need to re-examine the traditional methods of communicating modelling and appraisal results to decision-makers. “We are awful at dealing with uncertainty,” he said. “Is a single 30-year Net Present Value calculation really the most useful aid to decision-making?” he asked, suggesting that to think so was “absurd”. He also criticised the presentation of forecasts as ranges from high, medium, and low. “I regard that as little better than a single point prediction.”

A more explicit treatment of uncertainty was needed. He called for the “explicit quantification of the types and magnitude of different sources of uncertainty”.

Polak said decision-making processes also had to change. An environment was needed that rewarded decision-makers who were willing to adapt and learn and did not “cane” them for changing course.

“Modelling should be a fundamental part of institutional learning and growth; too often in the past it has just been a weapon in a fight with a paymaster,” he said.

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