Running motorways through cities, it seems, was not the best of last century’s ideas. Alana Semuels in The Atlantic describes the growing trend of Motorway tear downs in North America- “Highways Destroyed America’s CitiesCan tearing them down bring revitalization?“.

“Where urban highway construction did occur, in urban design terms, it was highly detrimental to the urban fabric; creating physical and psychological rifts that are extremely difficult to bridge and introducing a substantial source of noise and air pollution,” Shelton and Gann wrote. “Cities across the country continue to struggle with this legacy.”

As some of the highways reach the end of their useful life, cities and counties are debating the idea of tearing down urban freeways and replacing them with boulevards, streets, and new neighborhoods. Though it might sound like a headache, tearing down freeways in city centers can reduce air pollution and create parks and public spaces that bring cities together, according to Shelton.

“The removal of urban interstates is a growing trend in the U.S.,” Shelton and Gann wrote. This trend, if carried to its logical extreme, can yield sites of intervention that hold the promise of remaking the American city.”

I-980 Concept. Credit: Kenneth Garcia, Dover, Kohl & Partners via San Francsico Chronicle

One of the more captivating concepts has emerged in Oakland, where a multi-way boulevard is proposed to replace the divisive and underutilised I-980.

John King, “Time to rethink I-980, spur that cuts through heart of Oakland“, San Francisco Chronicle.

The vision of community advocates that the asphalt moat could be replaced by a landscaped boulevard connecting downtown to residential West Oakland — lined with a diverse mix of housing, perhaps with BART underneath — might be a naive mirage.

This is the cause of a small group of planning advocates called Connect Oakland, and they’ve caught the interest of Mayor Libby Schaaf and her administration.

The idea takes cues from San Francisco’s Hayes Valley, where the Central Freeway was rolled back after the 1989 Loma Prieta earthquake and the neighborhood has blossomed. Then there’s the local twist: I-980 was created expressly to connect to a second Bay Bridge. Which never got built. So perhaps this route could serve as the approach to a second BART tunnel instead.

Christopher Patano Concept
Christopher Patano Concept or capping I-5 in Seattle.

Doug Trumm, “Lid the I-5 trench downtown and consider building housing too“, The Urbanist.  In Seattle the plans to cap the I-5 and create and extensive park is being tweaked with a proposal to add more housing.

Patano’s vision for the northern half of the linear park is reminiscent of the much ballyhooed High Line in New York City that it seems just about every city now wants to copy (and which New York copied from Paris’ Plantee Promenade). Park space several stories up in the sky is a nice novelty but it’s hardly central to good urban design. High Line replicas run the risk of being exorbitantly expensive, underutilized flops.

If your city doesn’t have redevelopment opportunities or a serious shortage of park space and tourist attractions near its planned elevated park then it might just be a vanity project. Unfortunately spending billions of dollars to build a High Line-like park on top of I-5 between Eastlake and Capitol Hill might fall into that category.

On the other hand, Bonjukian’s extensive research has demonstrated the many benefits of a Downtown lid, which I believe outweigh the costs manifold. Capping the freeway Downtown would provide a marked improvement to the public realm in this neglected area of the city and hopefully allow additional blocks to be developed to relieve some of the housing pressure in Seattle. Plus, there is always the possibility that the much anticipated often delayed I-5 rebuild (to rejuvenate the decrepit freeway down to its foundation) will make capping a wider swath of I-5 feasible.

Zoning restrictions have been front page news across a handful of major newspapers including the New York Times Wall Street Journal, and Bloomberg. Restrictive zoning rules exacerbate inequality, limit mobility, and stifle wider economic growth. Clearly it’s time to bring in the cats.

Dan Keshat, “9 Things People Always Say At Zoning Hearings, Illustrated By Cats“, Austin On Your Feet.

“2. Nobody talked to me!” “9. This housing is too small for me!”


The hysteria around adding more housing to existing neighbourhoods has a certain universality across at least anglophonic countries. The zoning mechanisms also seem to be quite similar.

In “Single Family Zoning in Seattle and The Limited Logic of Euclid” Charlie Gardner describes the tangle of rules that enable exclusionary residential zoning- FAR, setbacks, minimum setbacks, and unit controls. 

Limitations on units are the the essence of the single-family designation, and lend the category its name.  This limitation often tests the bounds of rationality and common sense: on what ground, for instance, could one permit single-family homes on lots of 5,000 sq. ft. but prohibit a two-unit structure on 10,000 square feet?  Occupancy limits, covered thoroughly by Alan Durning in a series at the Sightline website, are a means of closing a final loophole and preventing detached, single-unit homes from being adapted to multi-household use as dormitory-style SRO housing with shared kitchen or bathroom spaces.

As should be clear from the above, the single-family zone, far from the straightforward concept that it it pretends to be, is a complex and artificial legal construct with many interlocking parts designed to forbid any deviation, no matter how slight, from the ideal.  Nor is some universal concept which is simply given recognition in law: in many or most countries, the idea of regulating housing in such a manner is not even conceived of. In Japanese zoning law, for instance, only bulk and height are regulated, and no attempt is made to restrict how the space within the building envelope is divided into living quarters.

via Mike Eliason and Old Urbanist

From a related but wider perspective, here are a couple of articles on urbanism and climate change.

Dimitri Zenghelis andNicholas Stern, “Climate change and cities: a prime source of problems, yet key to a solution“. The Guardian.

..cities are also a key part of the response. They afford multiple opportunities to dramatically reduce carbon emissions while sustaining prosperous standards of living. Indeed, there is no hope of reducing global emissions to safe levels if new and expanding cities are based on a sprawling, resource-intensive model of urban development.

Compact urban growth can create cities that are economically dynamic and healthy. The Global Commission on the Economy and Climate, a partnership led by 28 business leaders and former heads of state, and its flagship New Climate Economy project (NCE), found that compact, connected and coordinated cities are more productive, socially inclusive, resilient, cleaner, quieter and safer. They also have lower greenhouse gas emissions – a good example of the benefits of pursuing economic growth and climate action together.

Laura Bliss, “How Cities Became Heroes of the Environment“, CITYLAB.

But it really seems like cities went fully green in the 1990s, when the science around global warming began to gain momentum, and new academic fields like environmental science and planning blossomed. These new frames of thinking helped give rise to the concept of the “carbon footprint,” which helped policy makers and scientists “build sustainability arguments … that now often favor cities,” William Cronon, an author and environmental historian, told me earlier this year. That’s been an incredibly useful metric as cities all over the world now attempt to reduce their emissions and plan for the future.

With high density and low per-capita energy use, obviously New York City is a more ecologically friendly place to live than, say, suburban Scarsdale, we might now think. But this notion came fully into its own within just the last decade.

denser settlements tend to mean fewer emissions. That’s why so many local leaders got to walk into COP21 as heroes, not villains—and they’ve got a century of history to thank.

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  1. I think the whole “psychological rift” from motorways needs further exploration. It relies on a perceived Platonic ideal of the city where neighbourhoods etc. are organic, living things, where people know each other etc. And, in turn, motorways harm that.
    Now, I agree with that ideal, but some people don’t. To them, suburbia where each home is an island is the ideal.

    1. If you ever get the chance to visit Glasgow and where Woodland road meets the M8, no further study is required. It tore some great high density living out for 4 lanes of tarmac plus countless slip lanes. There are at least 4 junctions in a couple of Kms which require large amounts of land to deliver all those single occupied metal box’s onto dense urban streets.

    2. There’s no need to over think this. Their effects are clear both in delivering auto-mobility and in place destruction and severance. The pressing issue is not their meaning in theoretical sense but practical steps to ameliorate the negative effects of the existing ones, removal of the most egregious examples, especially those of low utility, but most importantly of all to stop adding and super-sizing them!

      This also requires a diversion of investment from them, to the more efficient, less destructive alternative urban movement systems. These bring with them the added benefit of incentivising alternative non-autodependant land use outcomes. So it is also ideal to keep an eye on regulation and demand side structures that may inhibit such improvements. This is how cities change for the best; through a process of incentivised morphology.

      1. This is how cities change for the best; through a process of “Incentivised morphology”. I like it Patrick. I think I know what you mean, but maybe an article putting up for debate what ‘incentives are needed’ wouldn’t be a bad idea.

        1. Been writing that one in my head for a while… among other things have been waiting to see what would happen in Paris. So now we know, even our visionless and obstructive government [on climate and pollution issues] has signed up for a ambitious change. This should mean everything changes around cities and transport from the government’s point of view. We have to contribute to helping them work this out, assuming, of course, there is even a thread of sincerity in this action….? I certainly intend to take them at their word on this. The first problem is showing that cities are a big part of the answer and not the problem, in this nation of urban skeptic urban dwellers!

          1. It would be great if the Key government used this historic agreement as the impetus to get out from the cloud of animal exhaust they’ve been hding behind and actually incentivised the vast array of easy wins we have in New Zealand to make a real contribution to achieving 1.5degrees. A large number of those wins come from favouring proximity over mobility and charging for the environmental impacts of mobility. Not big changes, rather the little nudges that help people make better decisions.

          2. “even our visionless and obstructive government [on climate and pollution issues] has signed up for a ambitious change”

            Ambitious? Not! A 30% reduction by 2030, of our 2005 CO2 and CO2 equivalent (CO2e) levels, is hardly “ambitious” – especially when you consider that the bulk of that comes from importing carbon credits generated (possibly fraudulently) from elsewhere on the planet, leaving the rest of the world to do the “heavy lifting”.

            Of course by not doing anything for so long, the Key Government can now pick the low hanging fruit of CO2 reductions and claim instant rewards for doing what NZ should have been doing for the last 7 years and get credit for it.

            As for real change, Simon Bridges might be aware and keen to change but the dinosaurs like Joyce, English, Brownlee and MoT to name a few are seeing the comet in the sky, rushing towards them, and are still carrying on like nothings ever gonna change.

            So the young guns like him have a hard row to hoe to even get National to accept a need for meaningful change, let alone their partners like ACT, and then convince the trucking and farming lobbies that they have to change their business as usual approach starting from now.

            And as transport and farming make the big two generators of CO2 and CO2e we create each year, its really up to those sectors to do the heavy lifting. That starts with a policy of “owning the problem”.

          3. “We have to contribute to helping them work this out, assuming, of course, there is even a thread of sincerity in this action”

            And right on cue, outgoing MP & Minister Groser said this morning on RNZ whe interviewed about 6:10am – that its “business as usual” for Government policies as far he is concerned (a no doubt Joyce, English and co as well).

            So I feel your trust in their sincerity is well and truly misplaced. And its still early days yet.

      2. Come on Patrick, your reply was over-full of over-long multi-syllables. Sounds like waffle and I don’t think you’re a sophist. You haven’t actually said ANYTHING.

        Why is severance bad? What is “place destruction”, exactly? Another well-defined term like “vibrancy” which I think means whatever designers want it to meet.

        I like to walk to the shops. Other people like suburban streets with big backyards. Now, one might be more EFFICIENT (the walkable city), but that doesn’t mean that the latter is “psychologically destructive” or any such waffle. Motorways just are. They don’t have agency (though they do have a bloody big agency…)

        1. Motorways are psychologically destructive in that they mean we no longer think of where they are a a place but merely a conduit between places. In this way they have at least to the average punter removed the place from existence.

  2. Further quotes from Hamburg’s City Vision Statement: ” Mobility – From Owning to Using”

    “The car is losing its importance as a status symbol, while the desire for flexible, convenient, environment friendly forms of mobility and transport is growing. This is apparent from the noticeably greater popularity of walking, cycling or riding a pedelec. These trends must be taken as the starting point for future oriented transport policies”.

    “Plans for this decade include expanding the fast local train service (details named) and a brand new underground line (U5) and an extension of the underground line toward Horner Geest. And only emission free buses from 2020 at the latest”.

    A policy change by the Key government to immediately curtail motorway spending and advance public transport expenditure and efficiency in the Auckland – Hamilton – Tauranga triangle is indeed ‘low hanging fruit’ in the emissions stakes and would take some pressure off our overseas earnings agricultural sector and significant National electoral constituency. If only they would have the guts!

  3. “much bigger than the plan for Victoria St here in Auckland. Better hurry up AC, AT, or you’ll have no bragging rights”

    I know I’m a man alone on this, but crikey I can’t see that Victoria St ‘linear park’ working. Unless by ‘working’ one means causing traffic chaos (for vehicles, not pedestrians, obviously). Why not just close off the CBD between Albert and Symonds Streets and be done with it?

    I can’t see the Manhattan ‘Green Line’ happening either – my guess is business will argue it will throttle commercial deliveries and that there is plenty of green space in NYC.

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