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Jeez, I hope this doesn't last too long...

Posted: Fri Aug 24, 2012 4:23 pm
by AlanOfTheBerg

Re: Jeez, I hope this doesn't last too long...

Posted: Sat Aug 25, 2012 7:07 am
by AlanOfTheBerg
jasonh300 wrote:So would 100% be 45 deg. or 90 deg.?
I imagine it would be 45deg where rise=run. Or run=fall. :o

Re: Jeez, I hope this doesn't last too long...

Posted: Fri Aug 24, 2012 10:54 pm
by bgodette
jasonh300 wrote:
fvwazing wrote:14% means the road drops 14m if you drive 100m. That is pretty steep.
What is that in feet? :lol: j/k

Yes, that's pretty steep. I did some research and the steepest grade on the U.S. Interstate system is 8%, and I have driven it (I-24/US-41/64 Westbound over Monteagle Mountain, TN).
For comparison, and I'm sure you drove it, the natural grade of Lombard St is 27% but the effective grade is 14% to 16%.

Re: Jeez, I hope this doesn't last too long...

Posted: Fri Aug 24, 2012 11:58 pm
by floppyrod84
We have 33% locally, and higher elsewhere.

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Jeez, I hope this doesn't last too long...

Posted: Fri Aug 24, 2012 10:21 pm
by fvwazing
14% means the road drops 14m if you drive 100m. That is pretty steep.

Jeez, I hope this doesn't last too long...

Posted: Sat Aug 25, 2012 10:02 am
by fvwazing
1m down for 1m of road? 90 degrees, of course.

Edit:
Oops, my bad. Definition uses horizontal movement, not length of road.

Jeez, I hope this doesn't last too long...

Posted: Sat Aug 25, 2012 9:24 pm
by fvwazing
That is how I calculated/interpreted those roadsigns all the years! But harling was so assured that I looked it up - http://en.wikipedia.org/wiki/Grade_%28slope%29 - and well, the difference is not sooo big if the percentage is small.

Re: Jeez, I hope this doesn't last too long...

Posted: Sat Aug 25, 2012 5:01 am
by harling
14% grade: arctan(0.14) = 8 deg.
27% grade: arctan(0.27) = 15 deg.
33% grade: arctan(0.33) = 18 deg.

Re: Jeez, I hope this doesn't last too long...

Posted: Sat Aug 25, 2012 7:54 am
by harling
AlanOfTheBerg wrote:
jasonh300 wrote:So would 100% be 45 deg. or 90 deg.?
I imagine it would be 45deg where rise=run. Or run=fall. :o
100% grade (1m down for 1m forward): arctan(1.00) = 45 deg.

The "grade" of a vertical cliff is infinite.

Re: Jeez, I hope this doesn't last too long...

Posted: Sun Aug 26, 2012 1:44 am
by harling
I try not to apply my Math degree to practical problems more than once a year. That was it. :-)