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Seeing (over the guardrail) is believing

 



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While my car was in the shop getting a new timing belt, I had the opportunity to carpool to work. My friend drives a large pickup truck and I was expecting to get a bit of a rough ride. Boy, was I surprised by the high level of quality that's been put into today's pickups! The ride and interior features rival those of most passenger cars, and there's ample room for anything you'd like to carry––inside both the truck bed and the crew compartment.

But the feature I liked best was the ability to see over the highway guardrails as we were driving down the road. With my little car I've always had a rather limited view out the windows, and the result is that I've seen some of the nation's best and worst guardrails. The net effect is that, from my perspective looking out the window; California, Nebraska, Kansas, Alabama, and Maine all look virtually the same to me––just a single band of gray or rusting steel.

But with a truck, the view is incredible. I saw trees and lakes and wildlife and "scenery."

So, this experience got me thinking. What is it about a passenger car that keeps you from seeing anything but the guardrail? Yeah, I know, it's the sporty low slung seating and the desire to keep the car's center of gravity low to avoid rollover accidents. But these aren't the dark ages––if we can't safely bring the driver up to see over the guardrails, then we ought to be able to engineer a solution to bring the scenic view down to the driver's eye level.

I was fortunate to be driving in the rain last week when the solution dawned on me. We can utilize the refractory properties of water to redirect the pretty light waves past the dull gray guardrails down into our passenger cars. The same technology and physical laws that make a pencil sitting in a glass of water appear to be broken can be used to bend the light beams down into the passenger compartment.

Now, to help get this design started, let's look at a few of the little things that will need to be considered during the engineering of the final product.

How thick do the windows need to be to contain the refractory water?

How much water (or water thickness) is needed to refract the light waves around the guardrails?

What happens if the water freezes in these windows?

If you put antifreeze in the windows, how much would that affect your vision?

Would prism-shaped glass reduce the amount of water necessary for refraction?

The first reader to provide an answer to one of Ken's questions above, complete with appropriate engineering analysis, will receive a Design News flashlight. We will also post your answer on our website. Please email your answer to kfield@cahners.com, along with your mailing address.


Author Information
This report is one of a series of occasional columns exploring the not-altogether-serious side of engineering by Ken Foote, a mechanical engineer at GDLS. You can reach Ken at footes@chartermi.net or email your comments to us at kfield@cahners.com.

 

HEAD WORK

Admiring the scenery on a cross-country drive, Ken sees a locomotive pulling a train of 50 cars at a uniform speed up a 1% grade. What is the required draw bar pull at the head end of the train if each car weighs 100,000 lbs and it is a special case in which rational friction may be neglected?

A) 25,000 lbs

B) 50,000 lbs

C) 100,000 lbs

D) 125,000 lbs

E) 200,000 lbs

See answer below.

Adapted from the Fundamentals of Engineering Examination, Eugene L. Boronow, Prentice Hall Press, 1986. The worked out solutions of all Headwork problems can be found on our website at www.designnews.com. Look for the Headwork link in the navigation bar on the left.

Answer: B

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