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Posts from the Urbanism Category


Danish Architect Jan Gehl on Cities for People: The Safe City

Sibelius Park, a housing complex in Copenhagen, has cooperated with the Danish Crime Prevention Council to carefully define private, semiprivate, semipublic and public territories in the complex. Subsequent studies have shown that there is less crime and greater security than in other similar developments. Photos: Jan Gehl

Editor’s note: Streetsblog San Francisco is thrilled to launch a three-part series today by renowned Danish architect and livable streets luminary Jan Gehl. The pieces are excerpts are from his book, “Cities for People” published by Island Press. Donate to Streetsblog SF and you’ll qualify to win a copy of the book, courtesy of Island Press. Visit the Island Press website to find many more great titles by the nation’s leading publisher of books on environmental issues.

Feeling safe is crucial if we hope to have people embrace city space. In general, life and people themselves make the city more inviting and safe in terms of both experienced and perceived security.

In this section we deal with the safe city issue with the goal of ensuring good cities by inviting walking, biking and staying. Our discussion will focus on two important sectors where targeted efforts can satisfy the requirement for safety in city space: traffic safety and crime prevention.

Throughout the entire period of car encroachment, cities have tried to remove bicycle traffic from their streets. The risk of accident to pedestrians and bicyclists has been great throughout the rise in car traffic, and the fear of accident even greater.

Many European countries and North America experienced the car invasion early on and have watched city quality deteriorate year by year. There have been numerous counter reactions and an incipient development of new traffic planning principles in response. In other countries whose economies have developed more slowly and modestly, cars have only begun to invade cities more recently. In every case the result is a dramatic worsening of conditions for pedestrians and bicycle traffic.

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Peru’s Traffic Menagerie

Different vehicles shape a different streetscape in Peru.

Our daily urban lives shape our imaginations in so many ways. Few things box us in like our everyday transit options, and the patterns of traffic that shape our sense of public space. These patterns themselves are historical of course. A quick look back at the famous Market Street film shot a few days before the 1906 earthquake shows how chaotic and unpredictable the flow of traffic was when San Francisco’s main artery hadn’t yet been paved and standardized. Similarly, leaving the U.S. and visiting other countries provides a fantastic opportunity to experience other assumptions and possibilities for urban space, and surprisingly perhaps, a different range of vehicles.

In Peru for a couple of weeks I first had to adjust to a major cultural difference–unlike California, pedestrians don’t have any legal rights, let alone cultural preference. When you start to cross the street at a corner in a Peruvian city, you better be ready to run. Because the cars are not going to wait for you, in fact they tend to speed up when they see someone trying to use the road space ahead of them. I noticed the same thing on highways too, a consistent refusal to yield to entering traffic, a universal assumption of individual ownership of the right of way. Here’s a video below the break we shot standing on a traffic island in Peru’s second largest city while waiting for the traffic to clear so we could cross the street.

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Transit: The Greenest Technology

Image © Peter Calthorpe & Marianna Leuschel

Editor’s note: This concludes our 5-part series of excerpts from Peter Calthorpe’s book, “Urbanism in the Age of Climate Change.”  Thanks to Island Press, a few lucky Streetsblog readers will be selected to receive a free copy of the book. To enter the contest, fill out this form. We’ll choose the winners tomorrow.

The most important community-scale system dependent on urbanism is transit. It has long been known that density and transit ridership are linked, but it goes much deeper than that. The key to viable transit systems is not just density but walkability and mixed use—true urban places. If people cannot walk the quarter mile to or from a station, chances are they will not use the transit. Conversely, if they can easily run errands and coordinate trips on the way to or from a station, they are more likely to use transit. European data show that the percentage of walk or bike trips always exceeds that of transit trips—often by more than two to one.27 In fact, walking by itself constitutes 30 percent of all trips in Great Britain (versus 9 percent transit), and in Sweden walk/bike trips are 34 percent of the total (versus 11 percent transit). 28 Transit supports and extends the pedestrian environment; transit is pedestrian dependent, not the other way around. The primary alternative to the car and all of its environmental costs is the pedestrian environment and the walkable urbanism that supports transit.

A good transit system has many layers, from local buses to bus rapid transit and streetcars, from light rail to subways and commuter trains. They all feed into and reinforce one another, and they all depend on walkable urbanism at the origin and destination. The quality of the interface from walking to transit, and from one form of transit to the other, is central to displacing car trips and is the greenest technology that urbanism provides.

The relationship among transit, urbanism, travel behavior, and carbon emissions is complex but can be summarized with one key quantifiable metric, vehicle miles traveled (VMT)—effectively, the amount we drive. VMT is determined by the number and distance of trips we take, and our “mode split”—the percentage of trips taken by various transportation modes such as walk, bike, car, carpool, or transit. Each household, depending on its location, income, and size, has an average VMT per year, which when combined with various auto technologies will generate its travel carbon footprint.

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Urbanism in the Age of Climate Change: Green Technology

Tassafaronga Village in Oakland features buildings "designed to the highest level of green standard...incorporating a wide range of complementary green strategies including solar power for on-site generation of electricity and hot water." Image: Brian Rose from David Baker + Partners Architects

Editor’s note: This week, we continue our 5-part series of excerpts from Peter Calthorpe’s book, “Urbanism in the Age of Climate Change.” This is installment number four. Thanks to Island Press, a few lucky Streetsblog readers will be selected to receive a free copy of the book. To enter the contest, fill out this form.

I was part of the passive solar architectural movement in the 1970s. Its core idea was to provide energy for buildings in the most direct, elegant way. We had disdain for complicated “active solar” systems, with their complex engineering, maintenance, and costs. The passive way was first to reduce the demands by building tight, well insulated structures, flooded with natural light, and then to let the sun’s radiation or the cool night air work with the buildings’ form to provide thermal comfort. The same approach needs to be taken in relation to the climate change challenge: we need to find the simple, elegant solutions that are based on conservation before we introduce complex technology, even if it is green.

We need to focus, ironically, on ends, not means. For example, in passive solar buildings, focusing on the end goal (thermal comfort) rather than the means (heating air) changed the design approach dramatically. It turns out that human comfort has more to do with surrounding surface temperatures than with air temperature in a building, so massive walls that absorb and store the sun’s gentle heat also provide a more comfortable environment without all the hot air. Or, if lighting is the goal, electricity and bulbs are just one potential means; a building that welcomes daylight is the simple, elegant solution—even better than a complex system of wind farms generating green electrons for efficient fixtures. Likewise, the goal of transportation is access, not movement or mobility per se; movement is a means, not the end. So, bringing destinations closer together is a simpler, more elegant solution than assembling a new fleet of electric cars and the acres of solar collectors needed to power them. Call it “passive urbanism.”

Once demands are reduced by passive urbanism, the next step is to add technology. Green urbanism is what you get when you combine the best of traditional urbanism with renewable energy sources, advanced conservation techniques, new green technologies, and integrated services and utilities. All the inherent benefits of urbanism can be amplified by a new generation of ecological design, smart grids, climate-responsive buildings, low-carbon or electric cars, and next generation transit systems.

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Urbanism in the Age of Climate Change: Vision California

A future San Jose Diridon Station with high-speed rail. Image: CHSRA

A future San Jose Diridon Station with high-speed rail. Image: CHSRA

Editor’s note: This week and next, we’re presenting a 5-part series of excerpts from Peter Calthorpe’s book, “Urbanism in the Age of Climate Change.” This is installment number two. Thanks to Island Press, a few lucky Streetsblog readers will be selected to receive a free copy of the book. To enter the contest, fill out this form.

California’s effort to implement its new greenhouse gas reduction laws has provided a comprehensive look at urbanism and its potential in relation to a range of conservation and clean energy policies. The Vision California study, developed for the California High Speed Rail Authority and the California Strategic Growth Council, measured the results of several statewide land use futures coupled with conservation policies through the year 2050.5 The results make concrete the choices before us, the feedback loops, and the scale of both benefits and costs.

California is projected to grow by 7 million new households and 20 million people, to a population of nearly 60 million, by 2050.6 It is currently the eighth-largest economy in the world and therefore provides an important model of what is possible. The study compared a “Trend” future dominated by the state’s now typical low-density suburban growth and conservative conservation policies to a “Green Urban” alternative. This Green Urban alternative assumed that 35 percent of growth would be urban infill; 55 percent would be formed from a more compact, mixed-use, and walkable form of suburban expansion; and only 10 percent would be standard low-density development. In addition, the Green Urban alternative would push the auto fleet to an average 55 miles per gallon (MPG), its fuel would contain one third less carbon, and all new buildings would be 80 percent more efficient than today’s norm. It does not represent a green utopia, but it is heading in that direction. The results of this comparison highlight just how much is at stake and what the costs will be.

Remarkably, the quantity of land needed to accommodate the next two generations was reduced 67 percent by the Green Urban scenario, from more than 5,600 square miles in the Trend future to only 1,850 square miles. By comparison, the state’s current developed area is 5,300 square miles.7 This difference would save vast areas (up to 900 square miles) of farmland in the Central Valley along with key open space and habitat in the coastal regions of the state. The more compact future means smaller yards to irrigate and fewer parking lots to landscape, saving an average of 3.4 million acre-feet of water per year—enough to fill the San Francisco Bay annually or to irrigate 5 million acres of farmland.8 Less developed land also translates to fewer miles of infrastructure to build and maintain. The annual savings would be around $194 billion for the state, or $24,300 for each new household—not including the costs of ongoing maintenance. In addition, the Trend future would cost more in police and fire services as coverage areas increase.

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Urbanism in the Age of Climate Change

Image © Peter Calthorpe & Marianna Leuschel

Image © Peter Calthorpe & Marianna Leuschel

Editor’s note: Today we are very pleased to begin a five-part series of excerpts from Peter Calthorpe’s book, “Urbanism in the Age of Climate Change.” Keep reading this week and next to learn how you can win a copy of the book from Island Press.

I take as a given that climate change is an imminent threat and potentially catastrophic—the science is now clear that we are day by day contributing to our own demise. In addition, I believe that an increase in fuel costs due to declining oil reserves is also inevitable. The combination of these two global threats presents an economic and environmental challenge of unparalleled proportions—and, lacking a response, the potential for dire consequences. These challenges will in turn bring into urgent focus the way our buildings, towns, cities, and regions shape our lives and our environmental footprint. Beyond a transition to clean energy sources, I believe that urbanism—compact, diverse, and walkable communities—will play a central role in addressing these twin threats. In fact, responding to climate change and our coming energy challenge without a more sustainable form of urbanism will be impossible.

Many deny either the timing or the reality of these challenges. They argue that global demand for oil will not outstrip production and that climate change is overstated, nonexistent, or somehow not related to our actions. Setting aside such debates, my book, “Urbanism in the Age of Climate Change,” accepts the premise that both climate change and peak oil are pressing realities that need aggressive solutions.

Responding to climate change and our coming energy challenge without a more sustainable form of urbanism will be impossible.

The two challenges are deeply linked. The science tells us that if we are to arrest climate change, our goal for carbon emissions should be just 20 percent of our 1990 level by 2050. That, combined with a projected U.S. population increase of 130 million people,1 means each person in 2050 would need to be emitting on average just 12 percent of his or her current greenhouse gases (GHG)—what I will call here the “12% Solution.”2 If we can achieve the 12% Solution to offset climate change, we will simultaneously reduce our fossil-fuel dependence and demonstrate a sustainable model of prosperity. Such a low-carbon future will inherently reduce oil demands at rates that will allow a smoother transition to alternative fuels—and the next economy.

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