Mark H. Reddig
I recently was reminded of a story my old high school physics teacher told.
He said that many years ago, the folks in charge of paving things in New York (who, judging by the amount of paving, are quite dedicated to their jobs) were having a problem with the city’s sidewalks.
It seems they were chipping and eventually breaking up, long before they were expected to need repairs.
A group of engineers was assigned to figure out what was causing the problem. Their first, quick deduction identified – just as in the film “Casablanca” – the usual suspects. In this case, trucks.
The genius squad noted that delivery trucks regularly drove up on the sidewalks. Some larger haulers drove the wheels on one side up on the sidewalks to get partly off the street.
The solution: Ban the trucks from the sidewalks. However, the sidewalks kept chipping, leaving the genius squad perplexed and discredited.
That is, until one of them decided to use some of the science they all said they were dedicated to. In this case, that basic, simple principle was the concept of pounds per square inch.
Sure trucks were heavy. But they spread their weight over several tires, each of which, as anyone behind the wheel knows, covers a considerable piece of ground. So one lonely scientist started calculating the pounds per square inch of various other items found on New York sidewalks. He tested everything. And what he concluded, our teacher said, was pretty startling.
The culprit in the case of the damaged sidewalk: high-heeled shoes.
OK, stop laughing. That’s really what he said.
I got this image in my head – huge herds of well-dressed supermodels on red high-heeled spikes, rampaging across New York in gangs, like some kind of freak version of a Godzilla movie – but one where everyone’s really good looking and very well dressed.
The problem with high heels is that they compress the whole weight of a human being into four tiny areas, a portion of the ball of each foot and the tiny, tiny spike of the heel. When our genius did comparisons, he found some women who created more pounds per square inch than an elephant.
Our teacher showed us the math. He used real weights. It added up.
But did New York ban the supermodels, as they so readily did the trucks? Take a stroll in America’s Big Apple, and it’s clear they didn’t.
I was reminded of this recently when I read about one of our fine state governors who, in justifying raising fees on trucks, used the oft-quoted statistic that every truck does as much damage to the highway as 10,000 cars.
One of our OOIDA members saw it too, and asked us to print the real facts. I turned to Paul Abelson, our senior technical editor. He remembered that 10,000-car figure, and he says it’s bogus. Here’s the Reader’s Digest version of where Paul says it came from:
The one-truck/10,000-car figure was based on a test of roadbed materials done on Interstate 80 in Illinois. The scientists doing the study noticed that during the test, the right lane took more of a beating than the left. They assumed that all trucks travel in the right lane, and all cars in the left, so the damage must be caused by trucks.
You may note some erroneous assumptions in the previous paragraph.
Well, one of my old teachers had an expression: “If your mother says she loves you, check it out.” So we did. Here’s what we found out (with more than a little help from Paul):
The average semi – the 18-wheeled, fully loaded, 80,000-pound rig – places an average of 100 pounds per square inch of pressure on the pavement.
Then, with the help of one of our OOIDA staffers (and her formal footwear), we calculated the high heels. What we found shocked us.
If an average-weight woman with an average shoe size is standing on high heels, not moving with both feet firmly on the ground, she puts about 18 pounds per square inch weight on the pavement. But if she’s walking, it’s a different story.
As Professor Paul (that’s what we call him when he proves he’s smarter than the rest of us) points out, at times, the entire weight of a woman in high heels is on the heel. With a heel that’s as small as 1/16 of a square inch, that puts the pressure at somewhere between 1,200 and 2,400 pounds per square inch.
Makes the truck seem kind of wimpy, doesn’t it?
But the anti-truck folks were not talking about shoes, they were talking about cars. And in that case as well, simple science proves that the one-truck and 10,000-car statistic is nonsense.
Bryan Gorak, a trucker from Morton Grove, IL, wrote in to give us a statistic on that count. An SUV – one of the most popular types of passenger vehicle on the road today – weighs between 5,000 and 10,000 pounds. So a truck weighs about the same as between eight and 13 Humvees – not 10,000. Smaller cars weigh in frequently at 2,000 pounds, which means a truck is equal to maybe 40 of those.
When you look at pounds per square inch, it doesn’t get any better for the anti-truck folks. One of my fellow Land Line staffers drives an SUV that comes in at 33 pounds per square inch pressure on the ground, while another staffer’s minivan comes in at 35. By that measure, the tractor-trailer is about three times the pounds per square inch of that minivan.
So what’s the lesson here? Well, it’s three fold.
First, the next time someone blames you for all the damage to the highways, you can tell them they’re wrong, and you can tell them that science proves so.
Second, the next time someone cites that bogus statistic about one truck equaling 10,000 cars while they’re trying to raise your taxes, call them and tell them it’s bogus. Tell them what the real facts are. Tell them how much you pay in taxes; let them know you’re covering your fair share – and then some.
And third, watch out for those high-heeled shoes. They’re a killer, that’s for sure.
Just ask New York.