ill Goodwin, Professor of Transport Policy and Head of the
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Centre for Transport udies at UCL, warns that now methods of measuring congestion must be found. If you want to sound off about a road transport issue write to features editor !Vic Cunnane or fax your views (up to 600 words) to Micky Clarke on 020 8652 8812.
dd Last month the Council for the Protection of Rural
England published an analysis of the Ten Year Plan for transport that I had written, Running to Stand Still. I argued that the plan, even if it was implemented in full, and in time, would have invisibly small effects on the average speed of road travel, whether one looked at trunk roads and cities (undetectably better) or motorways, towns and rural areas (undetectably worse).
These forecasts were not my own, but based entirely on reworking the official DoT forecasts, by some detective work and with the most welcome help of DoT officials.
I should explain that I was, and remain, a great supporter of the government's 1998 Transport White Paper, which I helped to write, and the change in transport thinking it articulated: current trends are unsustainable; we can't build our way out of trouble; we need to focus on demand management, traffic control and public transport; and we must be extremely cautious about the
1; previously exaggerated hopes for road-building as the core of 2 transport strategy.
• All the research which led to those conclusions still applies.
• But I did come to the view that there had been an error of F.; judgement on one of those strange, almost incomprehensible, § technical matters that are usually only of concern to transport
• modellers, and not even all of them; the mathematical measurement of congestion. Few would normally care, but in this case the mistake then had quite unexpected ramifications on the whole way the plan was described which—as far as I can make out—even ministers and their advisors did not quite realise.
So the plan is full of fine numbers like "a 6% reduction in congestion", but nobody knew what they meant. Even if the forecasts are perfectly accurate, they mean that changes in average travel times in 10 years would be an order of magnitude smaller than the average day-to-day variation due to congestion itself, equating to seconds per mile, and sometimes tenths of seconds.
Well, maybe I'm right, maybe I'm wrong. I'd like to think that people would take their view on this from reading the full report Running to Stand Stiff rather than on the basis of whether the finding is convenient or inconvenient.
A lot of the report is based on what many professionals are now saying, whether they agree or disagree with the government's transport strategy. Rather to my surprise (we don't always see eye to eye) a significant number of the leading transport consultants have said they agree with me.
But either way, it's an object lesson on how technical assumptions can interact with policy development. I agree entirely with government in according prominence to the reduction of congestion among the objectives of transport policy. However, my report argues that it is in the interest of the policy concerns of the government, and clarity of understanding of transport users, to devise a different measure of congestion as rapidly as is feasible to do so.
The current measure is difficult to interpret, revealing nothing about important aspects of congestion (such as queue length, unpredictable conditions, gridlock, day-to-day variability and instability) other than the average of all speeds on the average of all days. It is exceedingly difficult to monitor; likely to lead to unrealistic public expectations in advance, unlikely to correspond with public experience when success is reported; has some perverse policy implications (such as implying that congestion is always reduced by reductions in speed limits, even if they are ineffective); and is not suitable as a cornerstone indicator of the transport strategy.
Its continued use can only lead to embarrassment and confusion.