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Getting Across the Bridge Puzzler

The driver does nothing.

Exactly. He’s burned two miles’ worth of fuel. He doesn’t need to.

That’s a better answer than mine. I thought it would be that if the bird had hovered over the truck without effect, there would be no harm in it’s landing on it: the truck had already supported the bird’s weight through the column of air between bird and truck. They sure are precise with those weight limits!

I figured he’d be ok because of fuel burned. He’s only 20 tons, so that’s a pretty light load for a semi, and I’ve never seen a straight truck haul livestock. That would be less that a third of a load for a semi, so it would get pretty good mileage (for a semi). I’ve seen reports of dead head fuel mileage of between 7 and 9 mpg. At 9 mpg and about 7 lbs per gallon, he should be able to handle a little more than a pound and a half.

Everyone’s going to come out of the woodwork calling bogus on this puzzler though. We should all know by now that, ignoring the fact that it’s an exercise in thinking, they’re going to claim that no bridge would be engineered to break at precisely its weight limit.

Of course it’s the fuel. I edited that out of what I originally posted. I assumed 20 mpg.

It could also be methane from the animals.

No one even knows the weight limit of a 4 mile long bridge made out of bamboo and hemp, because no one’s ever built one.

20 mpg in a truck? Is the bridge downhill that way? You won’t get that in a super duty diesel pickup truck, let alone a class 9 truck hauling something!

Jeepers H. Christ on a bicycle! It’s called using a conservative estimate. That way no one can say “what if the truck got better mileage?” The Puzzler is NOT REAL. No one would drive a 20 ton truck over a bridge made of bamboo.

No need to get your panties in a bunch. I’d disagree that it’s a conservative estimate. I’d call it an erroneous estimate. I think a conservative estimate must still fall within the boundaries of what is realistic. I don’t know what kind of mileage we get with the semis on my father’s farm, but I know the two new F250’s don’t come close to 20 even when they’re not hauling anything.

Just mirroring your tone. No harm meant. How about “wildly conservative”?

"I think a conservative estimate must still fall within the boundaries of what is realistic."

In the same way that a four mile long bridge made of bamboo and hemp that can support a load of 20 tons is realistic? That squirming sound you hear is monkeys trying to fly out of my butt. Party on, Garth.

The truth is I picked 20 miles a gallon to make the math easier. I know roughly what a tenth of a gallon weighs and I didn’t want to look up the weight of a sparrow.


Party on.

He could pee in a bottle and toss it out the window

No solution like that works because the extra weight is already on the car. Unless he sees the bird coming from a distance, decides to whiz in a bottle and throws it out before the bird lands, that’s a non-starter.