Had Roadguy known how yesterday’s Crosstown discussion would go, he would’ve hired an auctioneer to handle the comments: The new segment will be eight lanes across, yes, ladies and gentlemen, eight lanes, do I hear nine? Nine! How about ten? Ten it is! I see a hand up over here for eleven…

Thanks to loyal reader Froggie, I think we decided that the project will have 13 lanes at its widest point. (If our friends at MnDOT disagree, Roadguy will let you know — I need to contact them anyway to clarify the HOV/bus component.)

Wider highways are one way to boost capacity, but as an e-mail from alert reader Spongebue pointed out last week, some places build their highways upward instead of outward:

I was visiting some family members in Honolulu, Hawaii, recently and thought I’d give you a photo of a highway they have there…. This is the Nimitz highway, or route 92. This stretch of the highway is interesting, as it has Interstate H-1 directly above it for about 2.5 miles. It’s like a really long tunnel, but more claustrophobic-friendly:

Spongebue pointed out that no Hawaiian freeway is truly an “interstate” — it’s not like you can drive to Oahu from an adjacent state — but, he notes, H1 and H2 get interstate funding and signage.

Designs like this have been used where land is scarce and/or expensive — along I-70 in western Colorado, for example, there’s a canyon so narrow that they’ve put the westbound lanes on top of the eastbound ones. And Roadguy remembers driving along a different Nimitz — a double-decker freeway that was flattened a few months later by an earthquake that struck the San Francisco area. More than 40 people who were on the freeway at the time were killed.

Minnesota, fortunately, is multiply blessed — not only are we quake-free, but double-decker and elevated freeways never really caught on here. They’re harder to keep clear of ice and costlier to maintain, and other parts of the country are now working to get rid of them because their noise and shadows divide neighborhoods even more than trench freeways do. Seattle has been going through some brutal billion-dollar debates over its double-decker waterfront viaduct (click here for the official government page and some animations), and you’ve no doubt heard stories about Boston’s monumentally troubled Big Dig.

So while we might be justified in cursing the engineers who designed the Crosstown’s crazy weaves, Roadguy takes some comfort in this fact: they could’ve left us with something far worse.

This entry was posted on Wednesday, April 4th, 2007 at 6:05 am and is filed under Scenes and stories. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.