The Tragedy of the Commons (or no congestion charge?)

This article was published in 2008, in Newsletter 79.

Have you heard of ‘The Tragedy of the Commons’?

On many tracts of common land many different ‘Commoners’ may have rights to keep cattle, sheep, pigs, fowl, take wood, peat or even dig for coal! Often these ‘rights’ belong to different sets of people, and conflicts will result.

One of the commonest (sorry) conflicts is with grazing. It is not that simple as there isn’t a finite amount of grazing, because if land is overgrazed, the amount of grazing available may be rapidly reduced over time. Unfortunately if commoners are selfish and there is no proper control, the person who has the largest flock/herd will get the greatest gain, but if people co-operate all can gain by ensuring overgrazing does not occur. In fact, counter-intuitively perhaps, the person with the largest flock/herd will gain more income if his flock/herd is reduced. In addition, although there may be ample grazing for sheep, because they keep the sward short there may be no suitable fodder for cattle.

I’m told some of the earliest examples of English law relate to these issues in the Forest of Dean. There, for example, animals can be ‘excluded’ by fencing from areas for many years to enable trees to establish.

Cartoon of Tragedy of the Commons

So what’s this to do with ‘congestion’?

Congestion is a more modern example of this problem with roadspace being in ‘common’. Like ‘The Tragedy of the Commons’ it differs from classic distribution of finite resources problems, in that increasing use leads to exponentially increasing problems. Hence ‘selfish use’ leads to us all being worse off, and even those ‘greedy of resources’ would be better off if resources were more equitably shared.

Fortunately, unlike overgrazing of commons, the situation is more easily recovered. We know that when near capacity, small increases in traffic result in vastly greater congestion, and we also know that cyclists and buses take up far less space per person than private motor vehicles. What we need is a method of persuading motorists not to use their cars at peak times, either by shifting their trips in time or by using other modes. If we can do that, for example by charging in the peak hours, congestion CAN be reduced, and if the money so collected is spent on improving facilities for ‘more sustainable modes’ even those who still need to use their cars will win, as their trips will be quicker, and for many whose ‘value of time’ is high, they will in fact be better off. This is the so called ‘win-win’ situation.

In this analogy I wouldn’t dare to suggest who are the pigs or the chickens, but perhaps we need a ‘Verderers Court’ in Cambridge to ensure that common rights on our roads are fairly distributed…

You can find out more about ‘The Tragedy of the Commons’ on Wikipedia, so it must be true.

Jim Chisholm