one in three hill

[69Boss302]

Saw it recently on Top Gear and heard it elsewhere. I know it's a steep hill but what are the differences between a 1 in(and maybe?) 2 and 1 in 3 hill?

[d c]

1 in 3 refers to the gradient of an incline / slope etc.
for every 3 feet travelled the incline rises (or falls depending which way you are travelling) 1 foot which appears as 1 : 3 with a triangle on our road signs.

sometimes the road signs are shown as a percentage here in the uk.
for example a 1 in 4 gradient = a 25% gradient

gradient.gif

[Big Daddy Kane]

You know what, now that you mention the 25% thing, it was in the Iowa driver's license study book.

If a hill's grade is shown on a sign in the US, it's always a percent as far as I know.

For example, I was trying to climb a 6% grade (1:17 I suppose) over the NA Continental Divide with W-rated summer tires on packed snow at 7500ft.

...Yeah, I didn't make it! Had to be pulled over the top by a US Government Forest Ranger vehicle. Brakes were not so effective on the other side, and realized the ABS system goes haywire if all you do is spin the tires constantly!

[69Boss302]

I knew I came to the right place.

Thank you.