Measuring Road Grade:

You can use Google Earth to measure the road grade. Use the line
measurement tool and set it to feet (or whatever unit the altitude is
listed as in your preferences.) Find the road of interest and click the
top and the bottom to measure the distance. With each click, measure
the altitude (listed at the bottom of the window.) Now subtract the to
altitude measurements--that gives you your "rise" and the "distance"
comes from the measuring tool. To get the road grade, just use the
formula:

rise/distance * 100 = road grade (percent)

I know a lot of you probably know how to do this measurement, but I am
posting this message for those of you who have not worked it out. My
guess is that the values are not meaningful for very short distances (
50 feet) because of the limits of Google Earth data.

I visited Baldwin Road in NZ (using Google Earth ) and did a few
measurements:

Full road: 17.9% grade.
Lower half: 11.6% grade
Upper Half: 23% grade
Top 100 feet: 30% grade

Ouch!

Next time you want to tell us that the road or trail you climbed was
very steep, use Google Earth to put numbers on it.


--
scott ttocs
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