In city planning there's a popular phrase: "Stop sprawl, preserve existing neighborhoods, maintain affordability. Pick two." It's a poignant observation of the relationship between these three goals and the tension between them — how in a place like Houston, homes remain affordable and neighborhoods maintain their character as long as sprawl can continue unabated; or how London can enforce an urban growth boundary to prevent sprawl, but without significant new construction in older neighborhoods its housing prices have reached astronomical heights.
For the uninitiated, green belts — sometimes known as urban growth boundaries — are undeveloped regions that surround many cities and limit sprawl while preserving green space. And as the Guardian notes, "[a]lmost anyone you talk to on the subject agrees that the green belt is one of the great successes of planning, anywhere in the world." They encourage more efficient use of developed land, keep nature close to home for city residents, and prevent the interminable sprawl of low-density development that characterizes many U.S. metro areas, especially in the Southwest.
But green belts have a dark side. London, home to perhaps the best-known green belt in the world, also has the dubious distinction of being the most expensive rental market in the world, recently overtaking Hong Kong as the city with the highest residential and commercial rents. As with any other artificial limits on the supply of new housing in an ever-growing city, green belts are at least partially to blame for London's affordability crisis. Some have also claimed that Portland's rapid increase in housing prices is partly a result of their urban growth boundary. The question is, then, how can we maintain access to green space and limit sprawl, while still allowing cities to grow naturally, in sync with demand?
One potential answer is to discard the idea of green "belts" and to replace them with "webs" — green space spread throughout the city that connects rather than contains it.
The problem with green belts, aside from the supply restrictions they impose on new housing, is that they're not particularly accessible to a large number of residents. Using London as an example once more, it's clear that residents of Central London are too distant from the green belt to consider it valuable as an open space resource, and ideally they would have other parkland at a more accessible distance. Green belts are undoubtedly wonderful resources for those that live within a mile or two of them — those that can afford to, that is — but inner city residents don't typically get to enjoy them, and for those that live beyond the green belt they simply add more time to each day's commute. It may be prettier than the average commute, but there's very little "green" about it. It would be much better to have them living nearer their work, in denser, more energy-efficient housing.
For a great example of what a green web could look like, Amigos de los Rios have a proposal for us in, of all places, Los Angeles County. The project is called the Emerald Necklace Vision Plan, named in honor of Frederick Law Olmsted, Sr., who designed New York's Central Park and Boston's Emerald Necklace park system, and his son Frederick Jr., who helped create a vision for LA parks in 1930 that was, unfortunately, never realized. The Emerald Necklace Vision Plan is pictured in part below:
Taking advantage of several existing LA initiatives, including the Army Corps of Engineers' billion-dollar LA River revitalization program, the Greenway 2020 Plan, and plans for a 38-acre park on top of the 101 freeway, the project would create a network of green space throughout the region and put parks within easy reach of millions of LA County residents. Just as importantly, it would provide safe, convenient routes for walking and bicycling throughout the city, and create value to promote the development of more homes and businesses near the trails, rather than in the suburban/exurban Orange, San Bernardino, and Riverside Counties.
LA is surrounded by water, mountains, and other cities, so it lacks a green belt, but the appeal of a "green web" is that it could have value in nearly any context. For Los Angeles, the number of properties that would need to be destroyed could be replaced 20 times over with new (re)development near green space — including affordable housing, which could be funded by (e.g.) a partial tax-increment on park-adjacent land. We'd have thousands of new, energy-efficient units near world-class active transportation corridors, and if there's one thing LA needs right now, it's more housing.
Cities like London and Portland have it easier, because they can build out their network by expanding development beyond their growth boundaries and leaving stretches of undeveloped space to create "strands" within the green web. The growth of the web into the existing urban fabric could then be funded by proceeds from selling off land and development rights in the green belt. The large majority of the green belt could be maintained while bringing much more accessible green space to residents nearer the core of their cities.
In cities with or without green belts, there are opportunities to use green webs to create value throughout a region, and unlike isolated park and infrastructure projects, they can cast a wide enough net to limit the impact of gentrification in individual neighborhoods. They can add desperately-needed housing in some of the least affordable regions, increasing density in some locations and spurring new investment in historically disinvested neighborhoods. They can provide residents with a wealth of green space that doubles as a transportation resource, and is, most importantly, actually accessible. Best of all, they can build off of existing plans, the Hollywood cap park being an excellent example.
[Feel free to comment if you can spot any weaknesses or opportunities for improvement, because this is very much an idea in progress. For example, how would this be funded in lieu of a tax-increment type funding source? Since full expansion would require condemnation of many homes and businesses, how do you go through that process in a fair, equitable manner (or is contrary to the whole idea of eminent domain)? If this sounds totally politically or physically impossible, can you suggest what might make it more plausible? Any ideas for names that are better than "green web"? Thanks!]