There’s an interesting post on “The Infrastructurist” blog that proposes a counter-intuitive, but seemingly very successful method of reducing congestion on motorways: tear them down. Here’s part of the post:
Though our transportation planners still operate from the orthodoxy that the best way to untangle traffic is to build more roads, doing so actually proves counterproductive in some cases. There is even a mathematical theorem to explain why: “The Braess Paradox” (which sounds rather like a Robert Ludlum title) established that the addition of extra capacity to a road network often results in increased congestion and longer travel times. The reason has to do with the complex effects of individual drivers all trying to optimize their routes. The Braess paradox is not just an arcane bit of theory either – it plays frequently in real world situation.
Likewise, there is the phenomenon of induced demand – or the “if you build it, they will come” effect. In short, fancy new roads encourage people to drive more miles, as well as seeding new sprawl-style development that shifts new users onto them.
Of course, improving congestion is not the main reason why a city would want to knock down a poorly planned highway–the reasons for that are plentiful, and might include improving citizen health, restoring the local environment, and energizing the regional economy. More efficient traffic flow is just a wonderful side benefit.
Sound dubious? Here are several examples of how three cities (and their drivers) have fared better after highways that should never have been built in the first place were taken down.
The blog post then gives a number of examples of where this has been done, including turning the Cheonggyecheon Freeway back into a river, not replacing the Embarcadero Freeway or the Central Freeway in San Francisco when they got knocked down by the 1989 earthquake there, and ripping up Harbour Drive in Portland, Oregon. The Seoul example is perhaps the most spectacular, as they went from having this:
To this:
In 2002, Mayor Lee Myung Bak pledged to renew South Korea’s capital Seoul by eliminating a 1970s-era highway that literally represented a paving over of the Cheonggyecheon River. His radical plan replacing it not with another road, but with a restored stream along the old riverbed. The immediate result of the intervention was a beautiful new 1000-acre park in the center of the city, lower pollution, cooler temperatures city-wide. What wasn’t expected, however, was the city’s reduced traffic volumes. After all, the road carried 160,000 cars a day before it was closed. But the highway’s closing was enough to convince thousands of people to drive less, or change their habits, as the city offered better public transportation options.
Now I’m not necessarily advocating that we rip out spaghetti junction (although it is tempting), but it is interesting to note that the concept of induced demand works in reverse too. Just as “if you build it, they will come” is valid, so is “if you get rid of it, they will go”. Perhaps one thing that we could/should dismantle is the disgustingly ugly concrete jungle that is the “interchange” between new North Road and Dominion Road. There’s no reason why that couldn’t just be a normal intersection, and become a nice little town centre.
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Very interesting concept, and I would love to see some of our motorways go or be slimmed down, but let me play Devil’s Advocate for a second (arguing at least against full removal) – SH1 especially is the main long-distance link though the Isthmus. So there’s a big argument to keeping it. Maybe remove about half the interchanges?
And while the Dom Road / Ian McKinnon interchange IS a massively outsized piece of infrastructure, the very isolation it stands in means it is not INDUCING traffic. I say we wait with pulling that one down until it is rickety and / or the land prices increase enough for the reduced footprint to pay for the change on its own (though who knows – that might even be the case already).
I dont think there are any state-highway motorways that can be pulled down due to reasons described above.
However this argument can certainly be used for removing road lanes in the CBD itself. Of course the usual suspects such as the disastrous Nelson/Hobson combo, Quay St, the Fanshawe Bridge. Also could include reducing the number of lanes on Queen St. Reducing traffic lanes would cause some more localised congestion the short term, but would push people of to PT and help dencongest the wider motorway network leading to/from the CBD.
Max, certainly I agree about the long-distance necessity of SH1.
An interesting thought about whether removing the Dom Rd/New North Rd intersection could pay for itself. Here’s what it looks like now:
And here’s what it looked like back in 1959:
That’s a seriously big piece of prime real estate that it’s eaten up.
Great stuff. There’s space all over the city that needs to be reclaimed from the grips of motordom.
The main issue is that it wouldn’t be prime land in all respects. Sure, you would get some significant land back after recreating a normal (probably still pretty big!) intersection, but it would be odd-shaped, scattered in four bits, and (for good or worse) directly on a major arterial. You’d also still have to cross the rail. All said and done, it probably isn’t enough to pay for it itself (especially as demolition apparently is also quite costly – didn’t they say that taking down the old Nelson Street off-ramp would cost a couple million?) What with the disruption any construction would cause here, you’d probably be looking at similar costs for taking it down and temporarily rerouting traffic.
Ah well, as I said, I don’t really mind it – it’s actually interesting to have it there, in its isolation. As long as we fix Dom Road and Ian McKinnon Drive to be more human scale and purposes…
The Cheonggyecheon “after” picture doesn’t excite me at all. The “before” was brutal and ugly, but now they have a small straight stream with uninteresting straight flood walls and there are still ugly roads and buildings nearby. It just doesn’t work for me. Part of this is the scale of the “river”… The north bank of the Yarra in Melbourne CBD has similar flood walls and I have no problem with that. And I think London’s embankments are brilliant, even with all the traffic on the north side of the river. Maybe if the Koreans had let the stream meander a bit rather than channeling it in a straight line? It just looks man made rather than natural.
It might meander a bit further along, hard to tell. Perhaps its design has a cultural element to it? I’m not sure.
I actually quite like the fact that it’s an obviously urban and created environment, after all it is in the middle of the city. The walls are a bit high I agree, but perhaps that’s for flooding reasons?
Good luck preaching this to the conservitives!
The e2 series (which screens thursday 7.30pm on tvnz7) has an episode on the Cheonggyecheon Freeway which is worth watching if you haven’t seen it already.
You can find it at http://www.e2-series.com (25mins)
Graham Reid wrote about the Seoul transformation here: http://idealog.co.nz/magazine/september-october-2008/features/its-all-about-seoul (this was when we were debating Auckland’s waterfront stadium)
“Sure, there were subsequent bribery charges, and the stream is more manufactured than natural (the water has to be pumped through)—but the six-kilometre walkway is undeniably pleasant, has led to ancillary development, and at one end there is an impressive spiral sculpture by Claes Oldenburg.
Today, Cheonggye Stream is the focus for festivals, a destination for tourists and locals—as was intended—and an example to Koreans and the world of what is achievable in this city.”
Queen Street was once a stream. Now wouldn’t it be nice to do something similar in the heart of Auckland?
I think starategically removed roads would be excellent for Auckland, done carefully it can increase accessibility…
What about removing the grade serperation of Wellesley and Symonds Streets? Now that the motorway no longer flows straight into Wellesley Street there seems to be not point to the grade seperation.
I would fully support that James, except that Symonds Street is a really really important bus corridor, and doing that would lead to extra delays for buses along it.
I did think that would be a down side of it. On the other hand you could see it as a traffic calming measure. That whole area from Kitchener Street on up is a bit of a mess. How about tear down the lower Hobson Street ramp and the council carparks and pedestrianise lower Hobson Street and put a nice quality development in where the carpark is. You could then turn much of the eastern part of Quay Street into a nice boulevard and the little triangler area into a park.
Definitely agree on Lower Hobson, what a stupid idea that was. I agree that the intersection would do good thing to Wellesley Street, I just think that its impact on bus priority on Symonds Street needs to be fully considered.
I agree as well, it might be interesting to see just what the effect would be. It might not be too bad given there are lights there for some inexplicable reason. I understand for traffic going north and turning into Wellesley Street, but why are lights needed for traffic going south?
To let pedestrians across I guess. But yes you’re right, there are already lights there so maybe things would be OK.
Yeah, I took a look on my way through today and there is a crossing there.
Now that the CMJ is finished and northern to port traffic can bypass the CBD, they can begin with the long promised removal of lanes from Quay St. Once Quay St is no longer the main thoroughfare the big ramp down from Hobson becomes kinda irrelevant. I was poking around down there just the other day and realised they could pull down the ramp, have a two lane road from Customs St to access Princes Wharf and the eastern viaduct and still have room to develop right along the side of the carpark building.
This would make lower Hobson st more like Fort St in width and allow a pleasant shared space environment, as well as making money off the development site and not commiting the cardinal sin of removing a carpark building.
I wonder how that would fly with the new council, downsizing excessive arterial roads to create waterfront development sites.
That would be great if they could reduce the width of Quay Street, maybe they could turn it into a Jellicoe Street style promenade. Then you’d have a great waterfront all the way from Silo Park to the port.
Un-grade separating Symonds/Wellesly would just be spending a whole lot of money for very little gain (and even some potential loss). There’s much more important things to be done. The Quay Street narrowing and changes to the western and northern CBD should really be the main focus. Especially as the central and east have gotten/will get a lot of love via shared space. The Nelson/Hobson parts need some TLC now – and changing those streets would fit right into the name of this post!
I would be keen to see Pitt Street narrowed as well and maybe Beresford Square become an actual square. I could see Beresford Square becoming a key public space particularly if the CBD tunnel is built.
Yes Pitt Street is unnecessarily wide. A hangover from the days before CMJ was completed. It should be one general traffic lane and one bus lane on each side.