% grade

Close but not quite accurate. % grade refers to vertical distance divided by horizontal distance. Think of a right angled triangle. If you are going down a 5% grade for 1 mile you would travel 1 mile (the hypotenuse). Using Pythagoras theorem your vertical distance would be 264', the horizontal distance would be 5,273'. Not much of a difference but the difference has to be noted when taking field notes and laying out a map. Sometimes surveyors mess up and you will see signs on the interstate saying 84764 ahead = 84770 back.

 

Actually it depends on which state you are traveling in...both formulas are used...not at the same time, but some states use the first and others use the second formula...the best thing for a driver to be aware of is the fact that there is a steep grade ahead so adjust your driving to maintain control going down the grade.

So with this info...which formula does ID use?

 

Since I use to build houses, I refer to grades as pitches. Ah, this ones a 4/12. jk

A long hill can change grade, but they will post the max.

 

Cool! Someone else asked this question. I was going to, but I did a thread search and found this.
I think I've got it now. I always kinda wondered what would constitute a 100% grade; sounds like it would be a 45 degree angle.
Not very practical, but still, inquiring minds wanna know.
It also makes it theoretically possible, although practially useless, for there to be a grade of over 100%. Probably only on a motocross course, I suppose.
-- Handlebar --

 

Do you get retarded also and coast down the hills?

 

Your are almost correct Lil Bit--but there are some exceptions I MUST POINT OUT!
#1--Any ex cornflakes drivers
#2--Any Big R driver outta White Pine
#3--All Yellow freight relay drivers outta Salty(swapping in Evanston)
#4--All French Canadians(with Canadian governors)on I-87 or 81!
#5--All Berdoo Trashcan linehaul drivers

OK I know it's a little outdated! But I'm old! LMAO
Just my $.02

 

The worst/most fun grades I've encountered aren't on the interstate. They're in PA and usually has a "All trucks must stop here before proceeding" sign. Then you get to do about 30mph the entire way down. I swear these things are at least 12% grade. And of course you take off when there's no cars around. A few minutes later when you're halfway down you look and there will be like 20 cars behind you.

 

Remember 30,000 pounds of bananas by Harry Chaffin ?? about a hill outside of Scranton Pa