Grade Percentages
04-23-2003, 05:28 PM
#31
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Re:Grade Percentages
Thomas, you are avoiding my question - here. I'll state it again:
IF a 45 degree angle represents a 100% grade, WHAT percent grade is 90 degrees? OR, if you don't like 90 degrees, because it has "no slope", use 85 degrees instead... Indulge me if you will - I'm not after your interpretation of HOW to calculate it, but rather, what you state the answer is... In case there's any doubt, I want to see if you claim, or can demonstrate there are grades possible GREATER than 100%
Plain enough?
At this point, the single greatest sticking point of our difference in the equation is what it is that constitutes the length-of-run as stated by DOT engineers - YOU apparently consider it to be that imaginary baseline, while *I* take it to mean the actual travel route and distance involved getting from a lower elevation to a higher one...
IF a 45 degree angle represents a 100% grade, WHAT percent grade is 90 degrees? OR, if you don't like 90 degrees, because it has "no slope", use 85 degrees instead... Indulge me if you will - I'm not after your interpretation of HOW to calculate it, but rather, what you state the answer is... In case there's any doubt, I want to see if you claim, or can demonstrate there are grades possible GREATER than 100%
Plain enough?
At this point, the single greatest sticking point of our difference in the equation is what it is that constitutes the length-of-run as stated by DOT engineers - YOU apparently consider it to be that imaginary baseline, while *I* take it to mean the actual travel route and distance involved getting from a lower elevation to a higher one...
04-23-2003, 05:49 PM
#32
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Re:Grade Percentages
Gentlemen,<br><br>Lary has already asked to keep this friendly. <br>While Lary hides from the animal activists...<br>Lets make sure we keep things civil.<br><br>This topic has had some good information. I do not want to have to pull out the<br>[move]
[/move]<br>keys.
[/move]<br>keys.
04-23-2003, 05:59 PM
#33
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Re:Grade Percentages
'scuse me?
As far as *I* can tell, it IS being done in a civil and gentlemanly manner - an honest difference of interpretation, but certainly NO insult or abuse in the slightest - unless I've missed something!
*I* think it's being discussed in a VERY congenial manner... If I or someone else has crossed over the line, feel free to point it out... I haven't tried to offend anyone, and certainly don't feel anyone has offended ME!
As far as I'm concerned, Thomas is a great guy - and undoubtedly is FAR better qualified in math and geometry than *I* am - we just have a small debate going on that basically involves interpretation of DOT terminology - we'll work it out, and might even end up on friendly terms! ;D ;D ;D
But believe me, I fully appreciate it that you are keeping a close eye on things - THAT'S what being a good moderator is ALL about!
;D
As far as *I* can tell, it IS being done in a civil and gentlemanly manner - an honest difference of interpretation, but certainly NO insult or abuse in the slightest - unless I've missed something!
*I* think it's being discussed in a VERY congenial manner... If I or someone else has crossed over the line, feel free to point it out... I haven't tried to offend anyone, and certainly don't feel anyone has offended ME!
As far as I'm concerned, Thomas is a great guy - and undoubtedly is FAR better qualified in math and geometry than *I* am - we just have a small debate going on that basically involves interpretation of DOT terminology - we'll work it out, and might even end up on friendly terms! ;D ;D ;D
But believe me, I fully appreciate it that you are keeping a close eye on things - THAT'S what being a good moderator is ALL about!
;D
04-23-2003, 09:46 PM
#34
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Re:Grade Percentages
If I am traveling on a 100% grade pulling a PSD and a travel trailer - I am only using 18% of my possible power. <br><br>BUT - - If I am traveling a 45% grade towing a loaded gooseneck with 18,000 pounds on it, I am using 22% of my possible power.<br><br>Thus we can conclude that if I drink 6 more beers I can tow a aircraft carrier up the Grapevine in California in OD.<br><br>Clear as mud? I think so ;D
04-23-2003, 10:23 PM
#35
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Re:Grade Percentages
"Clear as mud? I think so"
Oh, I dunno - about as clear and sensible as anthing the REST of us have posted on the subject!
And LOTS more entertaining! ;D
(EDIT)
JEEZE, I just looked at the mileage notation in your sig - you must Hotshot - that's a LOT of miles in a fairly short time, and with power mods to boot - had many mechanical failures in those miles?
Oh, I dunno - about as clear and sensible as anthing the REST of us have posted on the subject!
And LOTS more entertaining! ;D
(EDIT)
JEEZE, I just looked at the mileage notation in your sig - you must Hotshot - that's a LOT of miles in a fairly short time, and with power mods to boot - had many mechanical failures in those miles?
04-23-2003, 10:45 PM
#36
Administrator
Re:Grade Percentages
What I want to know is why they always use the same picture of a truck driving down the same triangle, regardless of what the actual grade is?
Shouldn't they use an actual representation of the actual grade in the picture for those of us who don't understand exactly what the "8%" means? ??? :
??? :
phox
[img width=150 height=150]http://highwaytrafficsupply.com/images/regulatory_signs.html/W7-1.jpg[/img]
Oh, I won't even mention how long it took me to find a linkable picture to post
Shouldn't they use an actual representation of the actual grade in the picture for those of us who don't understand exactly what the "8%" means? ??? :
??? :phox
[img width=150 height=150]http://highwaytrafficsupply.com/images/regulatory_signs.html/W7-1.jpg[/img]
Oh, I won't even mention how long it took me to find a linkable picture to post
04-24-2003, 10:45 PM
#38
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Re:Grade Percentages
Ok, I'll stick my neck out on this one --
My information (Pocket ref by Thomas Glover) has a table of % grade to degrees, and according to it, 45 degrees = 100% grade, and 90 degrees is infinity percent grade. This is determined by the formula: % Grade = 100 * tan(slope) or (100 * vertical rise)/Horizontal distance. From this I would conclude that:
a. % grade is rise/run
b. It is possible to have a grade greater than 100%
c. The hypotenuse is not the run.
Sounds logical to me 8)
My information (Pocket ref by Thomas Glover) has a table of % grade to degrees, and according to it, 45 degrees = 100% grade, and 90 degrees is infinity percent grade. This is determined by the formula: % Grade = 100 * tan(slope) or (100 * vertical rise)/Horizontal distance. From this I would conclude that:
a. % grade is rise/run
b. It is possible to have a grade greater than 100%
c. The hypotenuse is not the run.
Sounds logical to me 8)
04-25-2003, 10:26 AM
#40
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Re:Grade Percentages
[quote author=bulabula link=board=11;threadid=13700;start=0#129015 date=1050587356]<br>I agree. I always thought the grade was a ratio of rise over run. If the road rises 5 feet up per 100 feet of roadway, the grade would be 5%.<br>[/quote]<br><br>Correct, this is the easiest way to think it out.<br><br>Hence...<br>2.5% is 2.5' or rise in 100' of horizontal run<br>10% is 10' of rise in 100' of horizontal run<br>7.8% is 7.8' of rise in 100' of horizontal run.<br>...and so on.<br>
04-25-2003, 11:49 AM
#41
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Re:Grade Percentages
"Hence...
2.5% is 2.5' or rise in 100' of horizontal run
10% is 10' of rise in 100' of horizontal run
7.8% is 7.8' of rise in 100' of horizontal run.
...and so on."
It seems to come down to terminology - there is NO "rise" in a horizontal run - "horizontal" is flat, level - once you go beyond horizontal, you get to "slope" or "grade" - and my view has been that the above would be properly expressed more like:
"10% is 10' of rise in 100' of LITERAL, or actual INCLINED travel"
not as compared to an imaginary, non-existent HORIZONTAL baseline. Otherwise, it would be properly expressed as:
"10% is a 10' rise in travel *AS COMPARED TO* 100' of HORIZONTAL run"
... See the difference? When I'm driving in the mountains, and I drive 5 miles of curving road - climbing 1000 feet in that distance - I can easily figure the grade percentage, but I DERN SURE can't even GUESS what the length of that imaginary horizontal baseline might be - so how do I figure it? And WHY would I even WANT - or NEED - to know the length of that imaginary baseline, if I already knew how much I had climbed in a known travel distance? ??? ???
BUT, I'm outnumbered - and most likely wrong (not the first time!) My second problem, is I don't recall EVER seeing a grade displayed that was GREATER than 100% - I realize it would be uncommon in road travel, but NOT when used to measure or list grade percentages in other settings - and I STILL would like someone step up and tell me what percentage grade 85 degrees slope is - it's NOT "infinity", and it IS greater than what many claim/accept is 100% - so what IS it? Any takers?
But, it's been a stimulating discussion...
2.5% is 2.5' or rise in 100' of horizontal run
10% is 10' of rise in 100' of horizontal run
7.8% is 7.8' of rise in 100' of horizontal run.
...and so on."
It seems to come down to terminology - there is NO "rise" in a horizontal run - "horizontal" is flat, level - once you go beyond horizontal, you get to "slope" or "grade" - and my view has been that the above would be properly expressed more like:
"10% is 10' of rise in 100' of LITERAL, or actual INCLINED travel"
not as compared to an imaginary, non-existent HORIZONTAL baseline. Otherwise, it would be properly expressed as:
"10% is a 10' rise in travel *AS COMPARED TO* 100' of HORIZONTAL run"
... See the difference? When I'm driving in the mountains, and I drive 5 miles of curving road - climbing 1000 feet in that distance - I can easily figure the grade percentage, but I DERN SURE can't even GUESS what the length of that imaginary horizontal baseline might be - so how do I figure it? And WHY would I even WANT - or NEED - to know the length of that imaginary baseline, if I already knew how much I had climbed in a known travel distance? ??? ???
BUT, I'm outnumbered - and most likely wrong (not the first time!) My second problem, is I don't recall EVER seeing a grade displayed that was GREATER than 100% - I realize it would be uncommon in road travel, but NOT when used to measure or list grade percentages in other settings - and I STILL would like someone step up and tell me what percentage grade 85 degrees slope is - it's NOT "infinity", and it IS greater than what many claim/accept is 100% - so what IS it? Any takers?
But, it's been a stimulating discussion...
04-25-2003, 12:08 PM
#42
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Re:Grade Percentages
{whew}, if I could instill as much energy as has gone into this discussion into my teenage sons to mow the lawn, I'd never cut the grass again.<br><br>Personally, I would call a 90 degree grade a "wall" or "cliff" depending if my head was looking up, or down.
04-25-2003, 12:16 PM
#43
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Re:Grade Percentages
"Personally, I would call a 90 degree grade a "wall" or "cliff" depending if my head was looking up, or down."<br><br>*I* would call it a 100% GRADE - one foot of rise per one foot of actual TRAVEL!
04-25-2003, 12:27 PM
#44
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Re:Grade Percentages
Using the formula Thomas gave us to calculate percent from the tangent of the angle expressed as degrees, I get 1143%? Is that right? I think so, I hope Thomas can help us, as 85 is getting closer to undefined. I have figured this equation for figuring slope the "non-dot" way. 100[a(tan)]=x where a is the angle of the slope and x is the percent of slope. Of course, none of this means anything compared to the road signs we see, we need a formula to relate the dot's version of percentage slope to actual percentage slope. The dot's version is much simpler when actually on the road, since you are traveling on the "hypotenuse" of the equation, and you can just figure slope by looking at the odometer and measuring elevation increase. At the low angle generally travelled on a roadway, I would say the difference is neglegible anyways. Interesting discussion, TGIF. Let's all go camping. Jcamper
04-25-2003, 12:28 PM
#45
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Re:Grade Percentages
gary, it was a joke. A 100% grade could also be called an "A". ....an old school teacher joke.<br><br>What time are you normally on 10m? I'd like to see how well my homemade windom works.