I don't know why the turtle crossed the road, but if he does decide to do so, what are his chances of success?

It depends.  It ranges anywhere from "Good luck, little buddy" to crunch.  Based on my online sources, your average box turtle walks at between 0.2 and 0.6 mph.  That's 18 to 53 feet each minute!  Whenever I see a turtle on the road (as I did this morning), he's never moving that fast.  I guess when he's actually moving that may be right, but they usually stop and smell the asphalt several times as they cross.

Let's name our sample turtle Tommy.  Several other factors also determine the likelihood of Tommy making it across the road safely.

• How big is Tommy?  The bigger the turtle, the bigger the target.  Let's say Tommy is 5 inches.
• How wide is the road?  The wider the road, the longer he'll be walking across it.  We'll use a 2-lane road that is 24 feet wide.
• How wide is a car tire?  The bigger the tire, the harder it will be for Tommy to avoid it.  Let's use 8 inches for each tire (16 inches total).
• How many cars will pass by?  More cars mean more tense moments for Tommy.  Let's say there are 2 cars per minute.
• And once again, how fast does Tommy move?  This is the million dollar question.  He probably won't be running in a beeline from one edge to the other.  Also, he'll probably stop from time to time.  We'll use a walking speed of 0.1 mph (8.8 ft/min) which still seems pretty fast to me.

First, we need to define the danger zone for each time a car comes by.  Tommy presents a 5 inch target for each tire, and even if the tire hits the edge of his shell, I'm calling that a hit.  So each tire (8 inches) plus Tommy's size (5 inches) is the width of each danger zone.  Since there are two tires, (8+5)*2 gives us a 26" total danger zone.  The road is 24 ft (288") wide, so the chance of Tommy being in the wrong  place at the wrong time is 26/288, or a 9.0% chance of Tommy going to turtle heaven.

If there were only one car on the road, we would be done.  But Tommy isn't that fast, and our road isn't that deserted.  At Tommy's pace of 0.1 mph across a 24 ft road, he'll be on it for 2.8 minutes.  With cars driving by at a rate of two per minute, Tommy will be crossing paths with about 5 cars.

Our spare you the probability math (which I had to look up online), but under these conditions, Tommy has a 31% chance of being hit only once, a 6% chance of being hit exactly twice, and a 0.6% chance of being hit three times.  (He has almost no chance of being hit 4 or 5 times.)  Since it only takes one hit to take out Tommy, we add these chances together and say that Tommy has a 38% chance of being hit.  Or, a 62% chance of making it across safely.

Now, let's have some fun with the numbers.  What if Tommy falls asleep while crossing the road.  Instead of taking only 2.8 minutes to cross, he takes a 10 minute nap and it takes him 12.8 minutes!  Not good.  Tommy should have rested before making his trek.  He'll have to dodge not 5, but 25 cars, and he'll have only a 9.4% chance of survival.

Or, what if Tommy was fully rested and took the original 2.8 minutes to cross, but he was on a busier road.  What if there were not 2 cars per minute, but 6 cars per minute (one every 10 seconds)?  I hope Tommy filled out his will.  This gives him just a 22% chance of survival.

Finally, what if Tommy was sleepy AND crossing our busy road?  "Adios, tortuga."  He would have a frightening 99.92% chance of going to that big pond in the sky, and only a 0.08% chance of making it successfully.

So what have we learned?  A) You really CAN have fun with math!  B ) Urban sprawl has made life difficult for the turtle population?  C) We should be thankful that we don't have short legs like turtles.  Of course it's none of those and the correct answer is D) Mitch McConnell should always look both ways before crossing the street.