Tuesday, 11 November 2014

How to waste a staggering £15bn

Martin Mogridge was a transport economist.  He was originally a physicist who wore long hair and leather trousers, and a cultivated air of exoticism. His interests included science fiction and Victorian eroticism, and just before his untimely death in 1999 at the age of only 59, he began studying Hebrew.

Over the previous three decades, while the major cities of the world enthusiastically demolished their slums and built massive urban highways, transport experts had been puzzling over the phenomenon of how new roads – even widened roads – seemed to increase traffic.

Economists had noticed that, if there is more road space, then people find it worthwhile to pay to use their cars, if they had one. Then public transport attracts fewer paying passengers and the fares go up or services reduce, and even more people go by car. 

Even in the 1930s, they had noticed that new roads released what they called ‘suppressed demand’. Worse, then the traffic goes faster and the buses find it more difficult to negotiate traffic streams or cross big highways. It all combined together to create what was called the Downs-Thomson Paradox, described like this:

“If the decision to use public or private transport is left to the free choice of the individual commuter, an equilibrium will be reached in which the overall attractiveness of the two systems is about equal, because if one is faster, cheaper and more agreeable than the other there will be a shift of passengers to it, rendering it more crowded while the other becomes less so, until a position is reached where no-one on either system thinks there is any advantage in changing to the other... Hence we derive one of the golden rules of urban transport: the quality of peak-hour travel by car tends to equal that of public transport.”

That was a vital clue: the speed of road transport and public transport are linked, and the journey times door to door for both are often very similar. Mogridge realised that, in London, everything depended on the speed of the underground system, which is why the traffic in London has stayed at a pretty average speed since 1900. 

If you build more roads, people go back to their cars because it is then quicker than going by underground – until the point when the speed is so slow that underground travel is faster. Then they leave their cars behind and go by tube.

The solution to speeding up the traffic is therefore to speed up the main public transport infrastructure. What’s more, said Mogridge, this works even if you take space away from cars to make room for public transport. It was the thinking that led to plans like Crossrail – the new high speed underground line across London – as well as on Zurich’s successful strategy to reduce car use based on better pedestrian access and investment in trams. 

By the end of his life, Mogridge reckoned that traffic speed could be doubled just by reducing space for cars, though it remains difficult for public officials – at least in the UK – to act on this new law of traffic management.  Read more in my book The New Economics.

What applies to London also applies to he trunk road system.  What is really staggering is that David Cameron has announced road-building plans which fly in the face of this knowledge.  In fact, £15bn worth, about which he claims:

“This will be nothing less than a roads revolution – one which will lead to quicker journey times, more jobs, and businesses boosted right across the country."

If Mogridge was right, and I think he was, the very last thing this will do is boost journey times.  It is a staggering waste of money and it seems at the very least unproven that it will boost business, except of course the business of road-building.  Road-building tends to move jobs from the poor areas to the rich areas, and rarely the other way.

Every one of those extra lanes, built at such enormous expense, will attract the road traffic to fill them again and I feel despairing of the establishment's ability to learn anything very much - and their amazing ability to keep plugging away with their money at the futile and hopeless.

It makes you yearn for austerity.  It's a pity it has got such a bad name.  At least it meant a little forethought before slinging money around at all the old shibboleths.

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4 comments:

Peter Roberts said...

Only one problem here David, you wrote 'their money'. It's our money.

PS Good to see you at the Timebanking UK conference.

Barry said...

I came across Martin Mogridge a number of times in the 1960s. I always enjoyed his leather-suited interventions at transport conferences. We were of the same generation of transport planners. Our views coincided, mine were prompted by Jane Jacob's "The Death and Life of Great American Cities"(1961). Her views made me aware of the dynamic nature of transport systems.

In the 1960s I was a Civil/Municipal Engineer i/c transportation planning in Southampton City. Contrary to the conventional view of those times, I persuaded the City Council that we could pedestrianise the main shopping street, Above Bar, without first building roads to take the displaced traffic. We did it and sure enough, after a week or two of chaos, everything settled down and traffic congestion was no worse than previously.

Whilst I sense that it is now generally accepted that increasing road capacity, by road building or traffic management, releases suppressed travel demand - what we called "induced traffic"- it is not accepted that the reverse is also the case. Wherever there is suppressed travel demand travel speeds remain more or less constant irrespective of the road space available.

So why don't transport planners and traffic engineers offer planning options which would reduce travel demand? Quite simply it is because their vested interest is to develop plans which aim to reduce traffic congestion. By doing so they protect and build their empires - in-house or outsourced. As happens throughout the public sector.

Richard said...

I'd take it one further: close some roads to cars, "force" more people onto buses, which then go faster, leading to a new equilibrium with everyone going faster. This only works if buses are the dominant form of public transport (but that's most places outside central London).

Tom Druitt said...

Fascinating, and confirms with evidence what I have always observed. However, I'm interested in the statement "Road-building tends to move jobs from the poor areas to the rich areas, and rarely the other way". How does this happen? Is there a study somewhere that confirms this?