Elevated Freeways: The Low Road?

The Congress for the New Urbanism (CNU) promotes neighborhood-based development as an alternative to sprawl. As part of their Highways to Boulevards initiative they recently listed ten Freeways Without Futures — elevated urban freeways that they say wreak all manner of economic and social havoc on cities and are ripe for being torn down. The highway-building boom that started revving up in the late '50s to support our exploding car culture undeniably destroyed many urban neighborhoods, particularly ones where the less-wealthy lived. It "solved" two "problems" with a single solution. (And, frankly, it's a lot easier to push the poor folks around than the rich ones.) In addition to leveling great swaths of housing, it created noisy, air-polluting divisions between what was left. Elevated highways are, in theory, an answer to part of those problems. The noise and air pollution is lifted up above ground level, and the real estate is less interrupted. But clearly success is mixed at best — the areas abutting this kind of infrastructure are generally depressed and inhospitable. The CNU list (the result of an open nomination process and weighted by several factors including age, redevelopment potential, potential cost savings, and local support) suggests the best opportunities to "stimulate valuable revitalization by replacing aging urban highways with boulevards and other cost-saving urban alternatives... saving billions of dollars on transportation infrastructure and revitalizing adjacent land with walkable, compact development." The looming maintenance expense these aging structures are facing is, all by itself, a serious driver. But I'm not so sure about all the social benefits being claimed. Certainly a boulevard — with a lower speed limit, plantings, connected to the street grid — is going to have far superior commercial potential than a freeway. Usability goes up, along with real estate values, tax revenues (and rents, once again driving out the low-income population). However, I either don't have enough imagination to visualize or information to understand how routing freeway-volume traffic through a boulevard won't greatly elevate local pollution and congestion, creating a nightmare for commuters and pedestrians alike. Feel free to spell out the missing details in the comments. Related in BuildingGreen Suite:

· Americans Favor Short Commutes· Reclaiming Our Cities & Towns: Better Living with Less Traffic· Transportation Planning: It's Time for Green Design to Hit the Road· Asphalt Nation: How the Automobile Took Over America and How We Can Take it Back· Elevated Childhood Asthma Risk Near Freeways