You Might Be an Engineer If…


– you enjoy the commute to work because it gives you time to calculate benefit/cost ratios for all the decisions that must be made at home (and so prove that buying a new car when the old breaks down no more than three times a year is not a wise choice).


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When an engineer makes a decision, from which car to buy to how long to stay at a relative’s house, he will do a benefit/cost (b/c) analysis. We have discussed this before on

We may also have mentioned the importance of the number 1, more precisely 1.0, to include the significant digit to the tenths. Today, we will emphasize this. We could take this to the hundredth or the thousandth or the millionth, but for most simple calculations, the tenths or hundredths will do. For now, we will keep to tenths.

What makes this number important to the engineer is that it is the tipping point, or the figurative line in the sand for the engineer when making a decision. If a b/c calculation results in a number greater than 1.0, then the activity is worth doing. Again, this can be from buying a roll of toilet paper to driving to the store for Tylenol because one of his kids “says” they have extreme pain from a baseball hitting their shin.

The difficult aspect about calculating a b/c ratio is that frequently either the benefit or cost is not easily quantifiable. If everything was given a monetary value, that would make life easy. But how do you measure the amount of whining of a kid with shin pain? How would one measure the annoyance level of spending time at the house of the relatives? How about the cost of sleeping on the couch rather than in bed if one decides not to buy flowers for an anniversary?

Fortunately, engineers are very creative when it comes to putting value on things. In highway safety engineering, we put a value on human life. If that is the case, and it is, then we certainly can place a value on the whining level of a kid with a hurt shin, or the pain level that kid supposedly is enduring. And when we place a value on the benefit and the cost, it is a simple matter to find the b/c ratio and decide, quite logically, that, say, maybe flowers aren’t waste of money.

It all has to do with 1.0 – is the b/c greater than or less than this. Life can be no simpler.

The Cost of Dry Hair

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My wife was riding with me in the car. She had just washed her hair and didn’t have time to dry it, so she opened a window and started to wind-dry her hair. She made the comment that this was saving all that money using the hair dryer. (It was a nice day.) She then stopped and wondered how much it did save.

So, to run the numbers, as an engineer will always want to do:

C = kW x t x r


C = cost of electricity of using the hair dryer for one hair drying event, calculated in cents

kW = kilowatts used by the hair dryer

t = time of hair dyer use, in hours

r = rate of electricity cost, in cents per kilowatt-hour

For us, r, in the range of our confusing electric company’s tiered charges is around 5.5 cents per kilowatt-hour. The time, according to my wife (although I could have disputed this, from personal observation) would have been 5 minutes, or 0.0833 hours. The electric use rating of the hair dryer is 1875 watts, or 1.875 kilowatts.

So, we have:

C = 1.875 x 0.0833 x 5.5 = 0.86 cents

What I thought was that she obviously was not doing a full cost comparison between the cost of using a hair dryer. My calculation is only for the use of the hair dryer. But what about the extra cost of gas to propel the car with the added wind drag? On the other hand, there should be calculations made for the increase in air conditioning to cool down the home with all the heat added by the hair dryer. Then, there are the possibilities and the risk being taken that my wife will not hit her head on while we pass a branch, or a bird, or that she will not get chilled and get sick from drying her hair in the chilled air. This would involve probability and risk calculations.

When it comes down to it, it is just easier to dry her hair at home with the hair dryer.


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If an engineer goes out to the store with his non-engineer wife, there are a few things the wife has learned (hopefully) never to ask. They could be considering the purchase of a car or computer or a set of dish towels, it does not matter.

She likely has learned not to throw these questions out there from experience – long, slogging, arduous experience. Here are a few of the key questions not to ask. We will call them anti-questions.

Doesn’t that color look pretty?

What do you feel about this?

How about we splurge a little?

His wife might as well be speaking some Sumerian. The engineer will have no idea how to respond to the first two, and will easily respond to the last question with a resounding, “That would not be wise use of our funds.” brings marital help to all engineers and their spouses.

You are welcome.

Golden Gate Bridge, and Beyond


A month or so ago, I mentioned that I not only visited the Golden Gate Bridge, I also heard from an engineer I met that his favorite toy as a kid was a model of that bridge.

Another story from this engineer was that when he was a child, he and his brother would talk their dad into visiting really cool sites on vacations. But, remember, this kid’s favorite toy was a model of a bridge. So, on their vacations, they planned around stops to power plants, dams, landmark bridges, and maybe even a really neat wastewater treatment facility.

Some kids would love to plan their vacations so they could visit zoos, circuses, amusement parks, or some other temporarily fun-filled adventure. But a future engineer understands that a good vacation is one where the fun lasts for a lifetime, or at least a career.

If you have a child with engineering leanings, I will share this fact with you. Factory tours and visits to water treatment facilities are fascinating.

You Might Be an Engineer If…

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– most anyone in your family, if asked to describe you using one word, would take no time to think about it and say, “Engineer”, and consider the response all that is needed.


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A couple weeks ago, we learned that there are three basic questions that an engineer asks, either to himself, or to the family member spending family money, when considering the purchase of an item. The three are:

1. How much does it cost?

2. How long will it last?

3. Will it cause me to socialize with people?

Those, however, are simply the screening questions. A more complete list contains at least 8 questions when considering to purchase an item, the first three, plus five more (therefore, 8 – done without, but checked by, using a calculator):

4. What is the likelihood of the it breaking before the normal useful life?

5. What are the maintenance costs?

6. What are the costs to run or use the item? (like gas in a car or electricity in an electric toothbrush)

7. Will it help in any way to understand my wife (or girlfriend, or any female) better?

8. Will I ever have to make a presentation in front of people because I bought this item?

To go through all the answers favorable to purchase:

The answer to 1. should be very little.

The answer to 2. should be very long.

The answer to 3. should be, “No.”

The answer to 4. should be very low.

The answer to 5. should be very low.

The answer to 6. should be very low.

The answer to 7. should be yes, but skepticism to this answer means the weight of the answer is low.

The answer to 8. should be “No.” That’s a deal-breaker.


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