A really thought-provoking article in the Atlantic Cities looks at whether we need to fundamentally change our approach to congestion:
With a few notable exceptions, transportation planning practice in the United States is focused on managing or eliminating traffic congestion. Regardless of whether planners are advocating for highway infrastructure to improve level-of-service, or transit projects intended to “get cars off the road,” the underlying assumption is that congestion relief is an unmitigated good.
Such arguments are often based on the idea that traffic congestion and vehicle delay are bad for the economy. According to the Texas Transportation Institute, vehicle delay costs Americans $115 billion in wasted fuel and time each year. The common interpretation of such statistics is that our cities and regions would be so much more economically productive if only we could eliminate the congestion that occurs on urban streets.
But this begs the question: is traffic congestion really a drag on the economy? Economies are measured not in terms of vehicle delay or the amount of travel that people do, but in terms of the dollar value of the goods and services that they produce. If it is true that congestion is detrimental to a region’s economy, then one would expect that people living in areas with low levels of traffic congestion would be more economically productive, on a per capita basis, than those in areas with high levels of congestion.
It certainly seems that when it comes to transport planning, congestion is the ultimate evil that we will do just about everything to rid ourselves from. Auckland’s history, building such city-destroying pieces of infrastructure like spaghetti junction, Mayoral Drive, Grafton Gully and Hobson/Nelson streets, were all done in the name of getting rid of congestion. We also spend billions and billions of dollars of public money each year on transport – once again mainly in the name of ridding ourselves of congestion.
It had better be worth it right? Congestion must really be terrible for our society, our economy and our environment if we are willing to go to such extreme lengths to rid ourselves of it.
The researchers who wrote the Atlantic Cities article tested whether higher levels of congestion had some relationship with the economic success of a place. Presumably, if congestion is so utterly terrible for the economy (as is so often claimed, especially by road building companies interestingly enough) then cities with higher levels of congestion should also have worse economies. Except it seems the opposite is true:
With the help of my research assistant Wenhao Li, I sought to determine whether vehicle delay had a negative effect on urban economies. I combined TTI’s data on traffic delay per capita with estimates of regional GDP per capita, acquired from the U.S. Bureau of Economic Analysis. I used 2010 data for both variables, converted them to their natural logs, and modeled them using regression analysis.
And what did I find? As per capita delay went up, so did GDP per capita. Every 10 percent increase in traffic delay per person was associated with a 3.4 percent increase in per capita GDP. For those interested in statistics, the relationship was significant at the 0.000 level, and the model had an R2 of 0.375. In layman’s terms, this was statistically-meaningful relationship.
Such a finding seems counterintuitive on its surface. How could being stuck in traffic lead people to be more productive? The relationship is almost certainly not causal. Instead, regional GDP and traffic congestion are tied to a common moderating variable – the presence of a vibrant, economically-productive city. And as city economies grow, so too does the demand for travel. People travel for work and meetings, for shopping and recreation. They produce and demand goods and services, which further increases travel demand. And when the streets become congested and driving inconvenient, people move to more accessible areas, rebuild at higher densities, travel shorter distances, and shift travel modes.
This is a really interesting finding. It suggests that congestion may not necessarily be something we need to worry about terribly as being an inhibitor of economic growth. In fact, some of the responses to congestion – moving to more accessible areas, building at higher densities, using public transport more – may actually boost economic growth through reducing the amount we need to spend on cars (money that generally flies out of the country to the Middle East) and also boosting things like agglomeration benefits: productivity gains when we cluster activity together.
Of course in some areas, congestion will have a dampening effect on economic growth. This is mainly in terms of adding time it takes to shift stuff around the city. But the answer to that issue may well not be in building more roads, or even undertaking any measures to actually reduce overall congestion. It’s to give freight a congestion-free alternative:
It is nevertheless true that goods movement is growing in the United States, making it a transportation issue that cannot be dismissed lightly. Should a region discover that it needs additional capacity for freight traffic, plenty of capacity can be found by converting a “free” highway lane into a truck-only toll lane, which not only allocates highway capacity for goods movement, but which also generates the revenues needed to pay for the highway’s maintenance. Given that highway infrastructure in the United States is aging and in growing need of repair, and that the ongoing decline of federal gas tax revenues has made it difficult for many state and local governments to fund basic highway maintenance, such solutions are likely to look increasingly attractive in the future.
From a freight perspective, who cares how congested the roads are if you’re able to avoid that congestion. The same is true for developing a top-class public transport system – congestion no longer become relevant if more and more people can simply avoid it by catching the train or catching a bus along a bus lane or busway.
I think it’s time we got over our obsession with reducing congestion. It seems pretty clear that higher levels of congestion don’t dampen economic growth. We’ve just always based our transport policy around reducing congestion because it’s annoying – but if we develop better alternatives: tolled freight lanes for trucks, better railways, busway and bus lanes for people, then congestion doesn’t really matter anymore. As a bonus there’s probably a good chance that would all be much cheaper, and certainly less destructive, than our obsession with getting rid of congestion. So we can spend our money on more important things like health, education or even return some of it to the people. And we can save our cities from further destruction.
It’s a whole new way of thinking though…. are we ready for it?
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Yes, but also, even if ‘solving’ congestion is the aim building more roadspace isn’t the answer, and that’s pretty much the only way we attempt to do it, or indeed attempt to do anything in the transport sector, and it doesn’t work. It just floods the system with more traffic- driving; great, unless everyone is doing it. If Ak has a congestion problem it is because we have only invested in one complete transport network, the one we all have to use, the private vehicle system. Remember the vast majority of vehicles are cars not trucks.
The experience of congestion is unpopular and politicians do get it in the neck about this whatever its effects, so being seen to be doing something about it is big, unfortunately the easiest way to do this is to look like a road builder, no matter how poor the actual results are for the economy, or even congestion. Let alone the quality of the resulting city.
Example to support the above article is the development of Sydney’s North Shore which is held to have boomed into a strong independent centre because of relative constriction across the harbour.
I agree congestion is not a good measure of the road network’s contribution to economic performance. A better measure would be throughput, ie the amount of people & freight moved per unit of time. This would take into account the load factors of the vehicles as well as the speed and flow.
But that regression analysis you cited is really dodgy — without controlling for any other variables that might affect GDP, it’s possible that the relationship observed with congestion is totally spurious, or there could actually be a statistically significant negative relationship that is not being picked up. In order to inform policy decisions, a much more sophisticated analysis is required.
“In order to inform policy decisions, a much more sophisticated analysis is required.”
Has someone told NZTA this yet?
maybe we don’t need to worry about congestion as an inhibitor of economic growth, but there are other aspect that are hugely worrying arising from queues of idling cars
first air quality, maybe spend more on health as an ambulance at the bottom of the cliff, but improving air quality would be an excellent preventative measure
second, until every car is fitted with stop/start, our finite oil resources are being used to run the heater and the CD/radio of a thousand cars waiting at the traffic lights
a much broader view of economics in a societal sense needs to be brought to the case, as AS says, there could be a negative relationship
The economic case for road investment is usually made by valuing time savings, and assumes that all users prefer to pay the money for the road improvement and get the time savings rather than use the money for something else (like food). However the actual behaviour when users have to pay to use a tollway is that half the users prefer to keep the money than have the time saving. When the Eastlink tollway opened in Melbourne it was free for the first 2 weeks. After this when tolls were applied, traffic volumes halved.
Visually, the graph suggests there may be three trendlines. An almost flat line for the wealthiest cities, above 11. The trendline shown for average cities, and a much steeper trendline below the illustrated trendline. I would need to get hold of spreadsheet used to create the graph to do a thorough analysis but using the TTI data and a list of the 100 largest US cities it is possible to label 40 cities on the right hand side of graph with high certainty and thirty in the middle with less certainty. That confirms what human geography knowledge of the USA suggests.
The cities well above the graph’s trendline are either financial capitals, entertainment capitals or high-tech centres. They include (from right to left on the graph) Atlanta, Seattle, Chicago, Los Angeles, San Francisco, Dallas, Houston, New York, Las Vegas, San Jose, Nashville and Anchorage.
The cities well below the trendline are all capitols of farming states or former agricultural processing cities and some former industrial powerhouse cities from the 1950s such as Akron, Milwaukee, Birmingham, Cincinnati and Toledo. The cities close to the trendline are a mixture include Minneapolis, Boston, Detroit, Cleveland and New Orleans.
Rather than higher incomes creating higher congestion it seems the opposite is true. Cities that were prosperous in the 1950s and 1960s will have engaged in the frenzy of freeway and suburban sprawl construction. As there economies decline so do there populations. Since the congestion is the sum of delay per mile and miles travelled one would expect these declining cities to have surplus road and housing capacity. Thus, if GDP per capita below the average is a measure of how big their decline has been then one would expect the surplus road and housing capacity to increase with falling GDP per capita. If greater housing availability increases the proportion of workers able to live close to workplaces then the combined effect of less congestion pr mile and fewer miles travelled will produce a steep decrease in congestion per capita from seemingly small decreases in GDP per capita.
The cities close to the trendline include both declining and growing cities so the effect is smoothed by the mix of cities with undercapacity and overcapcity.
For the wealthiest cities it does seem that provision of public transport may be an important factor for the large cities, which are mostly on the right of the graph, but not for the smaller cities which are mainly in the middle.
Unfortunately I haven’t been able to identify the highest and lowest cities near the left of the graph, the fact that they are so far from the mean suggests they are the cities we could learn the most from.
This disaggredation provides a clearer picture but the underlying conclusion still seems to be that congestion is good.
There is an economically efficient level of congestion – a level at which it isn’t efficient to adopt either pricing or capacity related instruments to address it (let’s face it, there really are only two tool that make a significant difference, everything else is incremental in the short term, although may have more measurable effects longer term that have both negative and positive externalities).
People avoid congestion like the plague. It is why motorists adopt ratruns, it is why many avoid peak periods, it is also why elasticities of demand resulting from pricing are higher than stated preference surveys suggest they really are. For most people the time taken to travel somewhere isn’t useful or enjoyable, so they seek to minimise it. Unless one is sightseeing, people want to “do stuff” at locations, not whilst on the move, because the options whilst travelling are limited.
Values of time vary, which is why toll lanes appear to be a great option (the real problem is in their practical implementation). Those who value time highly can pay to have a quicker trip, those who don’t can sit in the poorly priced network.
You say in one line “Of course in some areas, congestion will have a dampening effect on economic growth” then “It seems pretty clear that higher levels of congestion don’t dampen economic growth”.
The bigger issue is that beyond a certain level, congestion creates a vast range of negative externalities. For a starter, beyond a certain point it means network efficiency is hindered, as throughput drops with less people and goods moving per km than would be the case if it was optimal. That’s hardly a good use of an economic resource and precious space.
Secondly, until the age of all electric vehicles, it creates waste in fuel consumption and pollution. Why tolerate that?
Finally, it treats all road users as if they have equal values of time and that the costs of delay on each are equal. The most extreme example where this is wrong is with emergency services, where time can cost lives. Less extreme examples are people missing appointments, flights or as a result make allowances with their time to take congestion into account when they’d rather be doing other things.
You might not think that matters, but given the strong public support for addressing congestion, it suggests they think otherwise.
Of course if you think the only way to resolve congestion is to build more roads, then you will think it is limited, but the elephant in the room is pricing. In the UK alone, it was estimated some years ago that simply changing the existing fuel tax/VED pricing system to an efficient national road pricing system would reduce delays by 49%, and effectively delay or permanently shelve tens of billions of pounds of highway improvements which wouldn’t be needed.