Tuesday, July 12, 2011

How Flat I Am.

On Sunday we traveled an extrodinary section of the canal. It goes 69 miles between locks. As we travel, I've been thinking about how extraordinarily flat that is.

On the highway we measure angle by percent grade. A 10% grade is considered a steep hill. How flat is the canal in percent? Well, there are no tides and little current, so the surface of the water is exactly flat (neglecting curvature of the earth.) The depth of the water we monitor on the depth sounder, I'm sure it varies no more than a foot along the length. Say two feet to be generous. Well, 69 miles is 364,320 feet. 2 feet of 364,320 is a 0.0005 % grade. That's really flat.

But the canal is man made. What about the surrounding terrain? We can observe that part of the time we are roughly level with the surroundings, sometimes below, and sometimes above. Indeed, there are many places where we look down on fields of crops, and a few places where we look down on the roofs of houses near the canal. I estimate that the surrounding terrain varies 30 feet above and below the elevation of the water. That means the average flatness of of the land is about 0.016 % grade. That's still amazingly flat. If we look locally rather than on average, there are slopes up to about a 3 % grade. Thus local/average variation is about 180/1.  (I presume there is a civil engineering quantitative definition of flatness.  I looked but I didn't find it.  Perhaps some reader will provide it.)

Those numbers are impressive. Everything is naturally very flat around here. Does that mean making the canal was easy? Hardly. There are long stretches where the canal sits high above the surroundings. The embankments containing the canal are made of soil and rocks that had to be hauled in from many miles away. In several places the embankments are so high that the local highways go under the canal. It was a really massive engineering job. Think of the primitive tools and transportation they had for the original canal. It is instructive that the canal was improved and widened three times in it's history. That suggests that as the technology of earth moving increased gradually, the size of the canal kept increasing accordingly. That lasted until the railroads, and later the highways, captured the market for freight and the canal became obsolete for commercial use.

Today, we are treated like kings on the Erie Canal. I'm sure that NY Canal Corporation employees know that they owe their jobs to recreational boaters, so they treat us well. By contrast, the Saint Lawrence Seaway is for commercial traffic and we were treated shabbily when we traversed it. Fortunately for us boaters, the canal's budget falls under the NY Thruway Authority. It is financed by road tolls and not taxes. That makes it less threatened in this era of cut backs.

By the way, east of this flat stretch is a section of the canal 70 feet higher than the surrounding terrain. That makes for really big embankments. I wonder how insecure it feels to live in one of those houses at the base of the embankment.  The Erie canal has a long and notorious history of blowouts and breaks.  In one, a canal packet boat was carried several miles from the canal by the flood and found stuck 19 feet above the ground in a tree.

p.s. Not every city tickles our fancy.  On the way west, we skipped Pittsford and Brockport.  On the return trip we stopped at both of those places for lunch and to see if we might like to stay overnight.  In both cases, it took us only 20 minutes to decide "No" and to move on.   Pittsford had a Starbucks which David would like, but it also had a big Birkenstock banner hanging by the canal, that should have tipped me off.   Today we're going to lunch in Palmyra, another place we skipped on the westward jaunt.

1 comment:

  1. Okay, you have piqued my curiosity: Is it the fact of an advertising banner by the canal in Pittsford that should have been a sign; or was it that it was a Birkenstock banner specifically (I hate advertising banners in general, but for myself the Birkenstock part would not be an additional negative).

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