Alert reader John was checking out the new Interstate 35W bridge last weekend when he saw something he didn't expect:
It looked to me like the east side was about 1 to 1 1/2 feet lower that the west side. ... Is that just an optical illusion, or is there really a discrepancy in elevation between the two sides? If it's real, how do they take care of it?
John's eyes were perceptive, if not perfectly so. The roadways that protrude a couple of hundred feet from each bank did not in fact line up vertically -- the difference was 7 to 9 inches, says Kevin Gutknecht of the Minnesota Department of Transportation.
It would be more entertaining if this had come as a total surprise -- "You moron! Next time use a calculator!" -- but engineers anticipated the discrepancy. It was the result of a few million pounds of scaffolding beams weighing down the portion of the bridge over West River Parkway. The downward force there pushed up the part of the bridge over the river, something like a seesaw.
The beams have since been removed, Gutknecht said, and now the downtown side "is about where it needs to be."
As for the horizontal gap -- there's a 7-foot space between the two sides -- it'll be filled with concrete this coming week.
Favoring a freeway
Minnesota is dotted with expressways -- divided highways that let you travel at freeway speeds but that have at-grade intersections. They are relatively easy to drive on, but there's almost nothing more demoralizing than going from a full-fledged freeway to a stop-and-go expressway, as alert reader Pete from Coon Rapids can attest:
