Local Transport Today is the authoritative, independent journal for transport decision makers. Analysis, Comment & News on Transport Policy, Planning, Finance and Delivery since 1989.

How to communicate uncertainty to decision-makers

Miles Logie, Minnerva, Windermere LA23
15 May 2015
 

Phil Goodwin’s comments on the variability of DfT road traffic forecasts (LTT 1 May) include reference to Tom van Vuren’s question on how decision-makers can handle additional information produced by transport models reflecting uncertainty. Elsewhere in the same issue, Luis Willumsen is quoted as wondering how models can cope when they are uprooted from standard comforting assumptions about equilibrium, which can seem even less tenable in a world of rapid technological change. 

For some time I have been taking opportunities when they present themselves to encourage transport modelling to take a more whole-hearted approach to incorporating uncertainty into its standard approaches. A typical and understandable reaction is to feel that obtaining even one set of results from complex forecasting models can be difficult enough in practice, so obtaining results for a wide spectrum of variations in scenarios and assumptions seems unrealistic. 

Against this viewpoint is the fact that other, non-transport disciplines have made significant strides in how to approach the topic, and the work on uncertainty in complex modelling by Sheffield and Aston universities (e.g. the MUCM Toolkit) merits a mention. Advances on the methodological front, however, might still be seen as simply making life difficult for decision-makers and, as they are the important ones, this needs real attention. 

My advocacy includes changing the terminology from ‘uncertainty’, which resonates with mathematics and methodologies and is suitable to inputs, to ‘robustness’, which relates to outputs and is how decision-makers should judge and be judged. This means that scenarios are presented both in terms of standard Appraisal Summary Table outcomes but also, significantly, in terms of their chances of failure to meet the expected outcomes. A robust outcome is therefore one in which changes in the assumptions have limited effect, in contrast to cases where there is a high risk that outcomes are unstable. This translates into a bet on the outcomes, say big benefits and big risk versus small benefits and low risk, which is a familiar situation for decision-makers to decide upon.

It does not always take much to discover whether outcomes are robust or not, but it can do, and ‘cottage industry’ modelling is not necessarily the best approach. 

Maybe the Transport Catapult can help make the transition?

 

Specialist Transport Services Manager
Warrington Borough Council
Warrington
GRADE 13 (£58,797 - £63,735)
Senior Transport Planner
Wigan Council
Wigan
Grade 9, £37,336 - £42,403 per annum.
Specialist Transport Services Manager
Warrington Borough Council
Warrington
GRADE 13 (£58,797 - £63,735)
View all Vacancies
 
Search
 
 
 

TransportXtra is part of Landor LINKS

© 2024 TransportXtra | Landor LINKS Ltd | All Rights Reserved

Subscriptions, Magazines & Online Access Enquires
[Frequently Asked Questions]
Email: subs.ltt@landor.co.uk | Tel: +44 (0) 20 7091 7959

Shop & Accounts Enquires
Email: accounts@landor.co.uk | Tel: +44 (0) 20 7091 7855

Advertising Sales & Recruitment Enquires
Email: daniel@landor.co.uk | Tel: +44 (0) 20 7091 7861

Events & Conference Enquires
Email: conferences@landor.co.uk | Tel: +44 (0) 20 7091 7865

Press Releases & Editorial Enquires
Email: info@transportxtra.com | Tel: +44 (0) 20 7091 7875

Privacy Policy | Terms and Conditions | Advertise

Web design london by Brainiac Media 2020