If there’s one over-riding dogma for transport planners throughout the past 50 years it would be this: “congestion is bad”. Almost everything that transport planning, traffic engineering and anything else related to this field has been about over the past 50 years is based on the belief that congestion is a bad thing, and we should do everything we can to minimise, avoid or – at best – completely banish congestion. A few years ago someone (we’re not really sure who actually) came up with the statistic that congestion was costing Auckland a billion dollars a year, or close to it. That figure (wherever it came from) has been used to politically justify much of the money spent on ‘improving’ Auckland’s motorway network over the past few years, in particular the almost religious belief that the Western Ring Route is the solution to all our problems.
However, all of this is based on an assumption – that congestion is a bad thing. Now of course we all hate getting stuck in a traffic jam, as it wastes our time, causes frustration and (possibly) wastes our petrol as we sit there doing nothing. So perhaps it seems nonsensical that congestion would be anything but bad. However, taking a broad view of matters if you really think about it there are a number of positive effects of congestion, that could lead us to really questioning whether traffic congestion really is enemy number one for traffic planner and transport engineers around the world. This post explores that possibility.
A classic example of a congested route in Auckland is Onewa Road on the North Shore. I drive this road reasonably frequently, including at peak times (I know, bad me, but I don’t really have any practical alternatives), and it does get very congested indeed. During the morning peak the road operates as two lanes – a general traffic lane that edges incredibly slowly down the hill from Highbury towards the Northern Motorway (at off-peak times this length of road shouldn’t take much more than 3-4 minutes to drive, at peak times it can take 20 minutes) and a T3 bus and carpool lane. Because the general lane is so congested, a lot of people catch the bus, carpool or drive during off-peak hours. All of these steps that people take to avoid the congestion of Onewa Road result in a positive outcome: higher public transport use, fewer people driving their cars, a greater spread of users throughout the ‘shoulder-peak’ periods and so forth.
However, these ‘benefits of congestion’ are rarely considered in the analysis of transportation improvements – with “time savings benefits” reigning supreme as the ultimate justification for roading projects. These time savings are, of course, created as the result of reductions in congestion – as people are able to undertake their trip quicker than before, thereby creating time at the beginning or the end of their trip they previously did not have, therefore creating a ‘benefit’. Now I think time-savings benefits are a load of rubbish and quite possibly non-existent, but that’s not really a debate for this thread. The bigger issue is “should we be worried about this?” Is it really the end of the world if our roads are clogged if we have a viable alternative? Clearly, the last bit of that is key – that there is a viable alternative in the form of a bus or (even better as it has its own right of way) a train.
An early chapter in Paul Mees’s book “A Very Public Solution“, which I have just started reading, probes this fundamental issue: is congestion really a bad thing? Could it be a good thing? An important aspect of answering that question is to look at who is affected by traffic congestion. Is it really a transport externality? The book states:
While dire estimates of congestion costs are frequently used to justify investments in roads, costing congestion is a difficult – if not nonsensical – task. The first problem is that congestion is not strictly an ‘externality’, the term economists use to describe costs that are borne by people other than those creating them.. Pollution from motor vehicles is an externality since it affects non-motorists as well as motorists. But congestion primarily affects the same group of people who produce it, namely road-users themselves. It may actually improve the lot of some residents, since slow-moving traffic makes less noise and is less intimidating for pedestrians and cyclists. And although there may be more accidents on congested roads, they will be less severe, owing to lower speeds. Congestion is only an externality in the sense that it is an effect each motorist imposes on other motorists.
So congestion doesn’t really affect anyone else but those on the road in a negative manner, and in some respects actually provides benefits to those other than the very people creating the problem. However, clearly it does seem as though there remains a problem – all that time lost while people are sitting in traffic doing nothing. Surely that’s economically inefficient? Surely there’s a real cost there?
This brings us back to the existence of ‘time savings benefits’, and also issues like induced demand that traffic planners and engineers tend to ignore because they upset the simplistic world of “predict and provide” they live in. Fortunately, there are a few smart thinkers out there who have looked at this issue more closely – including a guy called J.M. Thompson in a book called “Great Cities and their Traffic” – who outlines the following (quoted from Mees’s book):
Where a road and a rail system compete for patrons, Thompson argues that there will be an equilibrium between the two travel modes which ensures that they are of roughly equal quality. An increase in traffic on the road would raise travel times, encouraging some motorists to shift to public transport, a reduction in traffic would attract passengers from public transport until congestion rises to re-establish equilibrium. This equilibrium can be upset by changes to the quality of either mode. Improving the road system will produce a decline in patraonge of the rail service. This will cause a reduction in service levels, leading to a further decline in patronage. If sufficient rail passengers shift to the road on account of the decline in service a new equilibrium will be reached in which, paradoxically, both road-users and public transport patrons experience a worse level of service than before. Investing in road improvements has actually made everyone worse off.
Now aside from extreme situations like horrifically crowded trains in Tokyo, generally public transport works better the more patrons it has (as increased services become viable) while roads perform better the quieter they are. Therefore, taking steps to encourage people to use public transport rather than roads – through shifting the equilibrium in that direction – is likely to result in benefits to everyone.
Mees concludes that perhaps the best approach to congestion is for everyone to just relax a bit. There will always be congestion in large cities, but perhaps the focus should be on providing alternatives – as in cities with well developed transport alternatives people will be able to choose whether or not to endure it. The 1993 Vancouver Long Range Transportation Plan takes a similar viewpoint:
Congestion is usually considered an evil; however, allowing congestion to deteriorate for single occupant vehicles is a practical method of promoting transit and carpools. More congestion for single-occupant vehicles would magnify the impact of some travel demand management. For instance, buses/carpools in high occupancy vehicle lanes will gain an edge since the relative time saved by escaping lineups will be gone.
In fact, I think some level of peak hour congestion is actually probably a desirable outcome. If we had a complete absence of congestion at all times it would surely be a sign of huge over-investment in the roading network (if it was even possible, remembering the effects of induced demand). Places like Paris have more congested streets than a city like Los Angeles, but I’m doubtful that Parisians have poorer access around their city than their Californian counterparts. In fact, it’s likely the opposite is true. Slower traffic encourages alternatives means of transport that are often more sustainable, it encourages shorter trips and thereby encourages higher development densities and more mixed-use development. Which are all good things.
In the end, I think it’s stupid, and probably even counter-productive, to attempt to eliminate congestion. Instead, perhaps it’s more prudent to plan for an optimum level of congestion – keeping in mind other environmental, economic and social goals. If we set the equilibrium at the right level, in the end we will all benefit from it.