Adding an M to TAG: moral guidance and transport analysis

TAG is guidance, no more, no less. So where does this leave the modeller’s responsibility?

I have wanted to write this article for a while, if only to raise fellow modellers' awareness of the excellent article by by Nick Francis on “Civil engineers’ role in saving the world: updating the moral basis of the profession". Does it make sense to you?

I have been reviewing a number of TAG units recently (yes, I know, other people have more fulfilling hobbies…). And one point that I come back to time and time again, is wondering how prescriptive TAG, the Department for Transport’s Transport Analysis Guidance, should be. Frequently, the language is very open-ended (“Consideration might be given to using greater segmentation…”  and “It may be necessary to create an interaction between the highway and public transport assignments”– both from TAG Unit M1.1, Principles of Modelling and Forecasting, 2014).

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Tom van Vuren will be leading a session on moral modelling at Modelling World in Birminghham on 19 June. Reserve your space

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For me, these statements often don’t give firm enough direction: they can easily be ignored in practice, cutting corners when developing and using what should be sound modelling tools. I would like to see many of the words “may” replaced by “should”, and sometimes even “must”.

But I understand the Department’s conundrum: TAG is guidance, no more, no less.  Sadly, the guidance can be misused by practitioners in two ways: 1) if it is in TAG, it must be adhered to, and to the letter, (TAG compliance?)* which means that their model cannot be challenged; and 2) if it is not in TAG, then it doesn’t need consideration, which also means that their model cannot be challenged. Where does this leave the modeller’s responsibility?

Read the full article by Tom on his Linked In page...