In July 2012, a few months into the height of my Pittsburgh Bridge-walking, I pondered the definition of a bridge in What is a Bridge? and What is a Bridge? Part II. Asking what a bridge is may seem a little odd. After all, it’s one of those things that you know it when you see it. Yet, in walking bridges, I’ve discovered it really isn’t that simple (see the previous posts for more). In everyday life, the actual semantics of what a bridge is, is not important–you either cross it or you don’t and move on with your life. But if you’re trying to walk as many Pittsburgh bridges as you can (as I am) or count the number of bridges a city has to see which has the most of any city in the world (as others have), spelling out a clear definition of a bridge becomes important. By the end of my previous posts on the definition of a bridge, it seemed like I had covered almost all the difficulties: is a bridge still a bridge if it no longer bridges anything? what’s the difference between a bridge and a ramp? how many is one bridge?….then I went to Chicago and faced a new facet to this problem.
The issue Chicago brings up is best illustrated by the image above. Is there a bridge in that picture?….No, right?….Try again. If you walk past the buildings on the right, you get a new perspective on the seemingly solid ground you stand on.
Walking around on this street and the blocks around it, you may notice metal joints like those normally found only in bridges running across the roads and sidewalks. You may also feel the ground bounce like a bridge as a large truck drives by.
Are these roads, then, really bridges? If not, what are they and where do the bridges end (such as the Michigan Ave bridge across the Chicago River, visible in the back left of the image above-left) and the other begin?