Measuring grade on hills

pulsar wrote:
The Garmin dezl560 and 760 gps devices will display grade. I've not used the feature, so I can't comment on the accuracy.

Tom

I used the grade feature of the deal 560 yesterday, as we drove up the Black Mountain climb on I-40 in North Carolina. It seemed to be very accurate. Except for a brief 5% and even briefer 8%, it stayed between 6% and 7%. The hill is listed as a having a 7% grade.

On the long descent into Tennessee, the device gave no grade. I surmise that, because of the mountains, it was receiving signals from only 3 satellites. As aside, 3 satellites is sufficient for location, but 4 are required to measure elevation.

Tom

Ron Gratz wrote:

Airstreamer67 wrote:
---My little gauge indicates my rig is at a 10-degree attitude while climbing my driveway. That's about a 11% grade. Pretty steep for me to walk.

A 10-degree slope is close to an 18% grade.
Hope that doesn't make it seem even steeper for you to walk. :)

The percent gradient for slopes from 1 to 10 degrees are given below:

Slope in degrees in column 1
Gradient in percentage in column 2

1 ____ 1.75%
2 ____ 3.49%
3 ____ 5.24%
4 ____ 6.99%
5 ____ 8.75%
6 ____ 10.51%
7 ____ 12.28%
8 ____ 14.05%
9 ____ 15.84%
10 ____ 17.63%


For small slopes, to convert degrees to gradient,

multiply slope, in degrees, by 100 times pi (3.1416) divided by 180

or, approximately 1.75% per degree.

The actual ratio increases as slope increases. At a slope of 45 degrees, which is a gradient of 100%, the ratio is 2.22% per degree.

Ron

Consider a right triangle with one leg horizontal and the other vertical. The hypotenuse is the road. The acute angle formed by the the hypotenuse and the horizontal leg is the angle of inclination. The tangent of that angle is the opposite (rise) over the adjacent (run). That is, the tangent of the angle is the slope of the road. To convert degrees to % grade, one can use a scientific calculator to computer the tangent of the degree measure (and multiply by 100.) To convert from % grade to degrees, one needs to calculate the inverse tangent of the % grade, written as a decimal number.

Tom

45Ricochet wrote:

coolbreeze01 wrote:
The Sonora Pass 26% grade sign is my favorite :C

Me too

Thanks for the pic, that's the one :C

Not in real time, but you can do it later from the track profile. You can use the zoom tool to enlarge the area you want. Then pick you high and low points with the blue & red Marker Tools. You will then see your elevation in feet and your distance in miles. Change mile to feet and put put in here. You will now have a average percent of grade.

90 degrees is infinity rise is 100' lets say, run is 0'. 100% is when you rise one unit, go forward 1 unit. hence 45 degrees being 100%. 66degrees if I am doing the math really quick in the brain should be 200%,

I usually use 2% equals 1 degree. WHile not correct to a nats asset, gets me generally speaking, pretty close!

Marty

Ron and hotpepperkid, thanks for the correction and information.

I was going by my Pocket Ref book, which indicates in its conversion tables that "grades" relate to "degrees" by a factor of 0.9. This seemed logical, since a 100% grade (straight upwards) would seem to equate to a 90 degree attitude (perpendicular).

But, as I indicated, I understand Degrees better than Grades, although my college Degree obviously did not come via good math Grades.

Good thing the railroads didn't have me figuring how much of a grade their locomotives could pull on steel tracks in the Rockies.

Me and Jethro, we never did cipering very well.

And Ron, yes, my driveway suddenly seems so much steeper now.

Everything you want to know about slop, degrees and percents

Airstreamer67 wrote:
---My little gauge indicates my rig is at a 10-degree attitude while climbing my driveway. That's about a 11% grade. Pretty steep for me to walk.

A 10-degree slope is close to an 18% grade.
Hope that doesn't make it seem even steeper for you to walk. :)

The percent gradient for slopes from 1 to 10 degrees are given below:

Slope in degrees in column 1
Gradient in percentage in column 2

1 ____ 1.75%
2 ____ 3.49%
3 ____ 5.24%
4 ____ 6.99%
5 ____ 8.75%
6 ____ 10.51%
7 ____ 12.28%
8 ____ 14.05%
9 ____ 15.84%
10 ____ 17.63%


For small slopes, to convert degrees to gradient,

multiply slope, in degrees, by 100 times pi (3.1416) divided by 180

or, approximately 1.75% per degree.

The actual ratio increases as slope increases. At a slope of 45 degrees, which is a gradient of 100%, the ratio is 2.22% per degree.

Ron

coolbreeze01 wrote:
The Sonora Pass 26% grade sign is my favorite :C

Me too

The Sonora Pass 26% grade sign is my favorite :C