There's been a lot of Facebook chatter about how this access road to a new apartment complex in Boone, NC is going to be unsafe in the winter, especially because it is shaded and faces Northwest (toward the prevailing winds).
However, my question is this: in the report given to the county, the builders claimed the road would have a 15% grade. But this looks steeper than that for sure. Can anyone who is more of a road expert give an estimate on the grade of the road?
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fsphotos-a-ord.xx.fbcdn.net%2Fhphotos-prn1%2F534025_10201868297053080_2027884460_n.jpg&hash=5c99544c18d8fb5d786eeb8eb7a664bea3699c24)
First, what idiot allowed this to be built?
Second, even though this looks veeerrrryy unsafe (even when dry), the builders did a nice job.
Quote from: amroad17 on August 20, 2013, 08:06:39 PM
First, what idiot allowed this to be built?
Second, even though this looks veeerrrryy unsafe (even when dry), the builders did a nice job.
The entire development, including the road, is located squarely within Watauga County and not the town of Boone. The county's lax standards when compared with the municipalities (Boone and Blowing Rock) are well known. In addition to the dangerous access road, several residents are currently living in hotels because of construction delays and failed inspections.
looks like the hill is almost exactly tall as it is long. 45 degree angle at the tree line. 100% grade.
the question is, how far of an offset towards the foreground is there for the road to take a diagonal route, as opposed to straight up and down.
my eyeballing is "approximately 3 times as long as tall", so call it a 33% grade.
I may have lost a sine/arcsine conversion in there; I haven't done this stuff in years.
Easiest way to measure: take a spirit level and a protractor, and find the angle between the road and horizontal. Then convert that to a percent grade.
Quote from: agentsteel53 on August 20, 2013, 08:20:59 PM
looks like the hill is almost exactly tall as it is long. 45 degree angle at the tree line. 100% grade.
the question is, how far of an offset towards the foreground is there for the road to take a diagonal route, as opposed to straight up and down.
my eyeballing is "approximately 3 times as long as tall", so call it a 33% grade.
I may have lost a sine/arcsine conversion in there; I haven't done this stuff in years.
I eyeball it at 5 times longer than tall from treeline to treeline, around the switchback. 20%. 15% would be nearly 7 times longer than tall.
how is "grade" generally defined? average grade, likely, but over what length? the entire drop?
this becomes akin to measuring the length of a coastline. at some point, you'll run into some pretty useless numbers if you measure every pebble of road - but if a road is 3 miles of steady 5%, except with a 15% drop in the middle over 1000 feet, shouldn't that be taken into account? 500 feet? 100?
Quote from: agentsteel53 on August 20, 2013, 09:14:55 PM
how is "grade" generally defined? average grade, likely, but over what length? the entire drop?
This is something I've wondered, and I'm sure there is a generally accepted practice in engineering circles. At the extreme, if you measured the grade on I-80 from New York to San Francisco, it would come to about 0%.
There's a section of PA 487 heading north from Red Rock into Rickets Glen State Park which is posted 18%, but I'm sure there are short sections that are greater than that. The actual maximum immediate angle at any given point may come into play with trucks that are loaded and can only tolerate a certain angle for cargo, etc.
..the photo brought to mind this cartoon from a Volkswagen promotional book from the '60s with a bunch of
New Yorker-type cartoons. One showed a Beetle approaching a hill with a warning sign "40% Grade - Close Glove Compartment"
I'm no engineer, and this is just a guess being pulled out of my ass. But my guess would be the average over the distance where the absolute grade is over some minimum threshold.
I think 33% is a bit too high--I would put it within a few percentage points of the builders' 15% claim. (Even that is far too high given the winter traction issues.) There is little variation in the road width in the near and far portions of the picture, which is a sign that it has been taken with an extreme telephoto lens, which also tends to foreshorten horizontal distance and thus make grades look much steeper than they actually are.
I can see some kids trying to get some youtube video footage getting hurt pretty bad with that build.
Quote from: J N Winkler on August 20, 2013, 10:05:35 PM
it has been taken with an extreme telephoto lens, which also tends to foreshorten horizontal distance and thus make grades look much steeper than they actually are.
This. Go out there and measure it yourself, DSS5.
Doesn't look that unsafe to me. There are state-maintained roads in Kentucky and West Virginia that are worse than that.
Quote from: Avalanchez71 on August 20, 2013, 10:24:50 PM
I can see some kids trying to get some youtube video footage getting hurt pretty bad with that build.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi31.photobucket.com%2Falbums%2Fc378%2F1995hoo%2Fc030c140e571a2471d04785d4ef216d6_zps98cf2b44.jpg&hash=42ea1fda8963e6f0fd36bf1093bfd0275e6e92a5)
Quote from: J N Winkler on August 20, 2013, 10:05:35 PM
There is little variation in the road width in the near and far portions of the picture, which is a sign that it has been taken with an extreme telephoto lens, which also tends to foreshorten horizontal distance and thus make grades look much steeper than they actually are.
Looking at the rooftops, they are slanted slightly down to the right. Tilting the screen to level them produces less of a hill as well.
Yeah, that's no worse than the road down from my parents' house in Idaho (which is covered in snow all winter). The people who live up there will figure it out. I'd guess 20% max.
I love the little parking outset just before the hairpin. Must be for that emergency accident :pan:
Quote from: ET21 on August 20, 2013, 11:46:52 PM
I love the little parking outset just before the hairpin. Must be for that emergency accident :pan:
Passing zone for large vehicles, perhaps. You can see the two pickups getting pretty close to each other
As for how engineers measure grade, it's simple - you draw a line down the middle of the road (or a lane line, shoulder line, gutter, etc., but let's use the middle for simplicity, since it's what's usually used for a 2-lane road like this). Your line would not follow every pebble, but at the same time, you wouldn't cut through the top of a hill. Think of it as dropping a 2-inch thick rubber hose on the ground. The shape the hose takes will be a smooth series of curves and tangents, and that's your best approximation of grade.
Quote from: J N Winkler on August 20, 2013, 10:05:35 PM
I think 33% is a bit too high--I would put it within a few percentage points of the builders' 15% claim. (Even that is far too high given the winter traction issues.) There is little variation in the road width in the near and far portions of the picture, which is a sign that it has been taken with an extreme telephoto lens, which also tends to foreshorten horizontal distance and thus make grades look much steeper than they actually are.
I had the opposite analysis - those houses at upper left appear pretty distorted, which implies to me a wide angle held non-level to the horizontal.
Quote from: ET21 on August 20, 2013, 11:46:52 PM
I love the little parking outset just before the hairpin. Must be for that emergency accident :pan:
It's a little spectating area for watching maximum hoonage.
Quote from: Steve on August 21, 2013, 07:36:17 PM
As for how engineers measure grade, it's simple - you draw a line down the middle of the road (or a lane line, shoulder line, gutter, etc., but let's use the middle for simplicity, since it's what's usually used for a 2-lane road like this). Your line would not follow every pebble, but at the same time, you wouldn't cut through the top of a hill. Think of it as dropping a 2-inch thick rubber hose on the ground. The shape the hose takes will be a smooth series of curves and tangents, and that's your best approximation of grade.
That's how you measure grade at a specific point. But when a sign says a road has a grade of X%, is that the grade at a specific point, or is it the average grade over a section? And if the latter, how do they decide what section?
A bicyclist logged their ride up this hill (just today!) on strava.com, which recorded it as 0.4 mile at an average grade of "only" 12.1%. From the elevation chart, it appears a bit steeper near the start and a bit less steep near the top.
http://app.strava.com/segments/5191841
Quote from: formulanone on August 21, 2013, 09:05:08 PM
Quote from: ET21 on August 20, 2013, 11:46:52 PM
I love the little parking outset just before the hairpin. Must be for that emergency accident :pan:
It's a little spectating area for watching maximum hoonage.
I give this road an A- ;-)
Who wants to bet strava.com is using an outdated elevation model?
SR-526, here in Washington, has a section, while also SW 84th St. that it 9% and that road feels like you are going to slide out of your seat sometimes. This road does not appear to be anywhere near that steep.
http://bit.ly/16yu4Wu
Your argument is invalid.
My vote is 15%, because unless there's some solid reason not to, I'm going to agree with the professionals who built the road.
Quote from: wxfree on August 22, 2013, 02:48:04 AM
My vote is 15%, because unless there's some solid reason not to, I'm going to agree with the professionals who built the road.
It is a privately built and maintained road. The 15% is just what the company who built the complex originally said it was going to be.
Quote from: DSS5 on August 22, 2013, 11:04:51 AMIt is a privately built and maintained road. The 15% is just what the company who built the complex originally said it was going to be.
I would be inclined to accept that as credible since, in order to build the road, the development company would have had to obtain a permit from the county, and the application for it would have been accompanied by a set of construction plans for the road. It would raise uncomfortable questions for the company if it went out in public saying "15%" when the construction plans gave a much higher value.
I have some experience comparing roadway plans on paper with the actual field conditions, and slopes typically appear twice as steep as they actually are. So a slope that measures 2:1 (horizontal:vertical) will look like it is 1:1. That hillside slope that looks like a 45 degree angle (1:1) is actually more like 26.6 degrees (2:1), which would sound more realistic to me. I know on GA state highways we use maximum side slopes of 2:1 because that is the steepest slope that will still remain stable for grass and other vegetation to take root and not get washed away. All that being said, the builder's number of 15% is realistic. It's still going to be a steep road and potentially dangerous in icy conditions.
Quote from: Kacie Jane on August 21, 2013, 09:08:55 PM
Quote from: Steve on August 21, 2013, 07:36:17 PM
As for how engineers measure grade, it's simple - you draw a line down the middle of the road (or a lane line, shoulder line, gutter, etc., but let's use the middle for simplicity, since it's what's usually used for a 2-lane road like this). Your line would not follow every pebble, but at the same time, you wouldn't cut through the top of a hill. Think of it as dropping a 2-inch thick rubber hose on the ground. The shape the hose takes will be a smooth series of curves and tangents, and that's your best approximation of grade.
That's how you measure grade at a specific point. But when a sign says a road has a grade of X%, is that the grade at a specific point, or is it the average grade over a section? And if the latter, how do they decide what section?
Typically, when I see a maximum grade posted, it's the maximum grade achieved on that section (and I don't mean instantaneously on top of a pebble). I've seen "15% grade next 2 miles" (exaggeration) and you maybe have one 1/4 mile downgrade at 15% and even some flat sections in those 2 miles.