Elevated Trains and Affordable Housing

Commenting on a post about elevated rail transit, Angus Grieve-Smith remarks:

As I wrote back on Jarrett Walker’s post from 2009, the key is the noise. I live in Woodside, Queens, where the #7 train viaduct is made of unsoundproofed steel, and it’s impossible to have a conversation while the train is going overhead. Roosevelt Avenue is also noticeably darker where the tracks run overhead.

I think what needs to be thought about here is what’s the question? If the Red Line in DC ran elevated along Connecticut Avenue north of Dupont Circle, there’s no question that living alongside Connecticut Avenue would be less desirable than it currently is. But if those homes were less desirable then they would simply be . . . cheaper and you’ve have more of a mixed-income neighborhood where living right up next to the tracks was cheap but living a few blocks from the station would still be highly desirable. What’s more, since elevated rail would be cheaper to build than tunnels, for the same price as it took to tunnel from Dupont up to Bethesda, we could have built additional Metro lines.

The political economy reasons for not doing it this way seem obvious enough, but if I were building a city from scratch I would think that in general building a large number of elevated lines would be a better idea than a small number of subway lines. Speaking of which, has anyone played the SimCity iPhone ap?