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Public Transport & traffic congestion

Jarrett at Humantransit.org has another one of those “must read” blog posts up, this time exploring the linkage between public transport and traffic congestion – and seeking to answer the question “does public transport improvements reduce traffic congestion?” He starts off, quite interestingly, by stating this:

To my knowledge, and correct me if I’m wrong, no transit project or service has ever been the clear direct cause of a substantial drop in traffic congestion. So claiming that a project you favor will reduce congestion is unwise; the data just don’t support that claim.

However, before all the road-lovers start shrieking “ha, I told you so!”, he also says this:

To my knowledge, and again correct me if I’m wrong, there are exactly three ways for a city to reduce its traffic congestion measurably, quickly, and in a lasting way. (Widening roads is not one of these ways, because its benefit to traffic congestion is temporary unless new development in the road’s catchment is completely and permanently banned.)

Of course, the issue we’re talking about here is the effect of induced demand and the practical impossibility of trying to “fix” congestion through adding transport supply – either through widened roads or through public transport improvements. The matter of debate is whether we’re talking about longer-term or shorter-term improvements to congestion: as driving up the Northern Motorway yesterday at peak times the trip was amazingly uncongested – a situation which I think the Northern Busway has contributed to quite a lot.

Jarrett goes on to analyse the three things that he reckons would actually reduce congestion:

Economic collapse. Traffic congestion tends to drop during economic slowdowns, because fewer people have jobs to commute to, or money to spend on discretionary travel. A complete economic collapse, which causes people to move away from a city in droves, is always a lasting fix for congestion problems!

Reduction of road capacity. Ever since the demise of San Francisco’s Embarcadero Freeway, it’s been pretty clear that if you reduce road capacity for private vehicles, traffic will drop in response. Destroying the Embarcadero Freeway didn’t reduce congestion on the parallel surface streets, but it didn’t increase it much either. If you reduce road capacity, the remaining capacity is still congested, but this can still be called a reduction in congestion — especially if you use standard highway metrics like “lane miles of congested roadway.”

Correct pricing of road space. Congestion is the result of underpricing. If you give away 500 free concert tickets to the first 500 people in line, you’ll get 500 people standing in line, some of them overnight. These people are paying time to save money. Current prevailing road pricing policy requires all motorists to act like these frugal concertgoers. Motorists are required to pay for road use in time, rather than in money, even though some would rather do the opposite and our cities would be safer and more efficient if they could. Current road pricing policy requires motorists to save money, a renewable resource, by expending time, the least renewable resource of all.

So if public transport doesn’t reduce congestion, why on earth should we bother with it? Here’s what Jarrett says about that:

Transit’s role is essential, but its effect is indirect.

Transit raises the level of economic activity and prosperity at a fixed level of congestion. Congestion appears to reach equilibrium at a level that is maddeningly high but that can’t be called “total gridlock.” At that level, people just stop trying to travel. If your city is car-dependent, that limit becomes the cap on the economic activity — and thus the prosperity — of your city. To the extent that your city is dependent on transit, supported by walking and cycling, economic activity and prosperity can continue to grow while congestion remains constant.

Transit enables people who can’t drive to participate in economic life. This includes the disabled and seniors of course, but also the poor. During the US welfare reform debate in 1994-96, government began raising pressure on welfare recipients to seek and accept any employment opportunity. For the very poor living in car-dependent cities, the lack of commuting options became a profound barrier to these job placements. This is really an element of the previous point, since all employment, even of the poor, contributes to prosperity. But this has independent force for government because unemployed people consume more government services than employed people do. This benefit of transit should always be described in terms of economic efficiency, as I’ve done here, rather than appealing to pity or to alleged “economic rights,” as social-service language often implicitly does. The appeal of the social service argument is just too narrow, especially in the US.

Transit-dependent cities are generally more sustainable than car-dependent cities. They cover less land and tend to have fewer emissions both per capita and per distance travelled. The walking that they require is also better for public health, which produces further indirect economic benefits in reduced healthcare costs.

Intense transit service is essential for congestion pricing. Congestion pricing appears to be the only effective and durable tool for ensuring free-flowing roads while maintaining or growing prosperity. Congestion pricing always causes mode shift toward public transit, so quality public transit, with surplus capacity, must be there for a pricing plan to be credible.

Surface exclusive transit lanes (for buses, rail, and arguably two-wheelers and taxis) improve the performance of emergency services. This argument should be much more prominent, because even the most ardent car-lover will understand it. Few things are more distressing than to see an emergency vehicle stuck in traffic, sirens blaring. When confronted with this, all motorists do their best to help. But if the entire width of a street or highway is reserved for cars (moving or parked), and is therefore capable of being congested, it can be impossible to get out of the way of an emergency vehicle even if every motorist present has the best of intentions. Emergency response should be one of the strongest and most obvious cases for surface transit lanes. Motorists understand the need to drop to a low speed in school zones, to protect the life of every single child. Why do we not accept come degree of delay to save a child who may be dying somewhere else, because the ambulance is stuck in traffic?

I actually think it’s the first reason that Jarrett gives which is the most critical. Essentially, it is pointing out the difference between mobility and accessibility, that I have looked at in previous blog posts. Accessibility is, in my opinion, a measure of how easy it is to do the various things we want to do – while mobility is more of a crude measure about how fast one can travel around. Improving mobility can lead to improved accessibility, but that is not necessarily the case (and due to induced demand it may not be the case at all when it comes to road building and widening).

What public transport does is enable a more efficient use of the transport system, by most basically using the space the city dedicates to transport more effectively and intensively. If we take New York City for example, if it did not have the public transport system that it has then the 95% of people who work on Manhattan island and get to work via public transport would not be able to do so. The roads of New York City would be congested (probably quite extremely so) if there wasn’t the public transport system to carry the vast majority of people to work every day, but the streets are also congested now even though only 5% of the population drives to work if they work on Manhattan Island. The huge difference is the number of jobs that Manhattan is able to support because its transport system can get twenty times the number of people onto the island than it would be able to do if the only option was driving. That is an absolutely massive benefit to the economy of New York City, and probably the USA (and even the world) as a whole.

Bringing this back to Auckland, the same argument can be applied – both to public transport and to roads in general I suppose. Auckland’s level of congestion in the 1950s was undoubtedly far less than it is today, even though we’ve built all these motorways in the meanwhile. Does that mean it was pointless building the motorways – well that depends on what you were trying to “solve” by building them. If your goal was simply to reduce congestion, then the motorway building programme has been an utter disaster, and probably always will be. However, if you goal was to enable the development of the city and provide for people to access the places they wanted to access, then the programme could probably be considered a success.

I suppose the fundamental question now though is whether we can continue to provide for Auckland’s growth while retaining the current levels of congestion (or not letting them get too much worse) through building more motorways or through investing more in public transport. I’m strongly of the opinion that we’ve pretty much maxed out the number of additional roads that can be built, and also that our unbalanced approach to transport policy over the past 60 years has meant that our level of economic activity has probably been limited more than it should have (this recent post backed that up). In other words, our transport system has proven to be fairly inefficient at shifting people around the city, because it has been so heavily roads focused, and that has limited the attractiveness to businesses of many parts of the city (particularly the CBD) and/or has forced them into spending a lot of money on transport (in particular on providing parking) that would have more usefully been spent elsewhere to compensate for the poor public transport.

However, because current economic evaluation manuals and general political thinking on transport is so obsessed with “fixing congestion”, I am loathe to completely adhere to the “public transport won’t fix congestion” argument. Public transport, particularly rail transport because it’s completely ‘off road’, does have the ability to ‘take cars off the road’, which I think has a definite congestion-reducing benefit. In the longer run, yes that benefit will be eaten away by induced demand, but I think it will certainly last longer than any benefit created by widening a road: as that will just encourage more people to drive. I suppose in short I would agree that public transport won’t “fix” congestion, but I would say that it will probably do a better, and more long-lasting job, of reducing congestion than investment in new or (most particularly) widened roads could ever hope to achieve.

(Oh, and the social inclusion, sustainability and emergency benefits are certainly not to be sneezed at either!)

10 comments to Public Transport & traffic congestion

  • Nick R

    You could argue that public transport does ‘fix’ congestion, not in a systemic citywide level, but on a personal or group level.
    Personally I have hardly set foot (ass?) in a car for the last six months since moving into a house where no one drives. I haven’t thought about congestion (or parking, or gas prices) for six months now, let alone experienced it. So for me, on a personal level, the availablility of good transit has fixed congestion completely.

    So what if a large proportion of the population was in the same boat, say 50%? If half the people in the city never experienced congestion (I’m dreaming here, but it’s just an example) could we say it was fixed?

    • I was thinking that too Nick. If we take NYC again, most commuters would be on the rail system which means tha while congestion still exists – the vast majority of the population can avoid it. If there was no off-road PT then everyone would experience the congestion.

  • Nick R

    I guess the distinction is between fixing congestion and fixing the impact or outcomes of congestion.
    So while the first seems to be tending toward impossible, the second is perfectly possible by simply avoiding the need to travel in traffic.

  • David

    I think it is important to carefully define what one means by congestion and how one measures it. If the accepted measure of congestion was something like “the number of minutes spent waiting in traffic per trip made” and all trips, including those made by transit, were included in the denominator it would be clear that transit does actually reduce congestion. (It also makes it clear that road widening does not reduce congestion once induced demand kicks in.)

  • Nick R

    I guess that is the difference between congestion and mobility. Congestion is something of a “more roads is the answer what was the question again?” situation. By defining the problem as vehicular congestion one immediately narrows the solution to a small set of options related to shifting heaps of cars at the same time no matter what the cost.

    So, how about road pricing? Let’s borrow five billion and build Auckland a serious rapid transit system, then use the revenue from pricing the existing roads to pay for it. That would cure congestion and increase mobility at the same time, but I can’t see Joe Public taking that one on the chin.

    • James B

      I guess one advantage of having a CBD cut off by motorways is that setting the boundaries should be really easy. I count only 12 roads leading into the CBD (not including off-ramps). That is assuming that you have set the boundaries at the motorway and the railyards.

  • karl

    This post leads me to another interesting point. We hear (from the opponents of PT) that the Auckland CBD has fewer % of all jobs than before, etc… and therefore, we should not think PT will work.

    Well, we can turn that argument on its head quite easily: the Auckland CBD may well be a less attractive place to work because it is harder to get there than it should be by PT – and despite absolutely inundating the CBD with car access options, those are stuffed too, every morning. So if we build the CBD rail tunnel, and more busways, it will actually get more attractive to work there because you can get more people into the CBD, increasing development opportunities and intensification.

    Worldwide, more and more people are moving to the cities. Even in the USA, the flight to suburbia has started to reverse. The arguments of the anti-PT brigade just don’t hold water.

    • You’re right, and that is probably the biggest long term benefit of the CBD tunnel, that it will encourage CBD development. That is important as CBD workers tend to be high-wage high-productivity workers. Furthermore, if we are to encourage big companies to set up in Auckland then it will be in the CBD that they will have their offices. This is essential if we want to avoid NZ becoming the branch office of Australia.

  • Riccardo

    Great post – one of your best so far.

    Reality is I’ve been stuck in traffic jams (as a driver) in London, Paris, Hong Kong, Dubai, Toronto and others. All cities with great public transport. That is really the only point – that there is an alternative.

    You can get from one side of Paris to the other in 2 hours using the Peripherique, the permanently jammed ring motorway. Or you can use rail transport and do it considerably quicker.

    Auckland will have ‘made it’ when it has rail or segregated bus transport that you can say is absolutely quicker, full end to end, over typical journeys, than driving.

    Remember too the ‘anti-PT brigade’ is not about economics, its about power. If a road lane holds 2000 cars per hour and a rail line can carry 50,000 per track per hour, I can’t see how the issue becomes about roads.

    The reality is the tribes and tribal leaders who dominate decision making see THEMSELVES as the beneficiary of road spending. THEY don’t want to ride the trains themselves. It’s all about them, not about society.

  • Vincent

    Absolutely right Ricardo, BUT, and why I love the work admin et al do here, the best hope we have of altering what those in power so selfishly do is to fight them with hard facts, data, and reason. While also trying to enlist numbers behind us and attempting to limit their numbers by appealing to their self interest. This is why I still think advocating rail and off line buses [RTNs] as the best way of fighting congestion is so important; most of Auckland’s voters see the only thing wrong with the present system is that the roads aren’t wide enough, as they are sold this as the solution to their only problem: congestion. Sell RTNs as getting grandmothers and undergraduates out of THEIR way on THEIR freeways, because most can never see themselves using PT in Auckland, [although they do when on holiday in London etc and I believe many will do it once it is there and fast and clean and modern]. They are only thinking of the frustration they sometimes experience in their piece of fine German engineering by [in their minds] the incomplete motorway system. We also need PT to be sexier which is why the delay in electrification is so disappointing. More and more people are changing their view on this and the new stations and the improved service [esp. with the Northern Busway] help enormously and we can’t let Joyce break the momentum started by Britomart… But you’re right it is about Joyce and Key and their mates standing around an Omaha BBQ or heading to the airport in a limo: they hear no dissenting voices. We are dismissed as greenie dreamers or, if we get any power, dangerous greenie dreamers to be brought down [Mike Lee]. National voters are car drivers; losers and lefties ride transit [in their world].

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