Advantages of Elevated Rail

Here in the Midwest, the most iconic semi-local transit infrastructure is, naturally, the Chicago El, and specifically the Loop.While the El is not entirely above ground (the Red and Blue lines go underground through downtown), the name and the brand are both about the elevated lines. This contrasts strongly, of course, with a city like London, where the most significant and iconic intracity rail network is literally called the Underground (though, as we'll discuss below, the DLR is often elevated, and there is of course a whole system called the Overground as well).I also recently visited Montréal, which is building out two different mass transit lines on very different principles: one tunneled belowground and one elevated above it. And one of them is way over budget--the one with the tunnels.So naturally, I have some thoughts on why elevated rail works well, and why (given those cost advantages we're seeing in places like Montréal) more cities should use it.To be clear, I'm not…