Jim Frame, post: 373863, member: 10 wrote: I asked why he wasn't going to use GPS and he replied that they don't have any.
You should have offered to shoot a vector for him right then and there and maybe picked up a couple hundred for an hours work.
Now that I've gotten his methods, back to the paint. I must be getting older because this kind of thing bugs me deeply. I mean, how 'bout a good description in the field book? Do you really need to paint things up to be seen from outer space?
Don't even get me started on flagging....
Jim Frame, post: 373863, member: 10 wrote:
This was left behind by a guy I bumped into this morning who said he needed to run levels " about 5 miles" for an elevation certificate. He claimed we were at the closest BM to his project, though I doubt it. I asked why he wasn't going to use GPS and he replied that they don't have any. Instead, he's going to trig it with shots about 1800 feet. And lots of paint.
Considering the amount of time he's going to spend running an elevation that won't be right, if he does this two or three times, he's wasting enough money to pay for an X-90 unit that would give him good results.
I had just started a 12-hour day running static sessions, so wasn't in a position to offer any help to anyone.
Not sure what is meant by "trigging", but I have run many loops that we term, "trig loops". They close very well, typically, unless you fat finger something.
Around here, the relief might require 5 turns to get up a hill that would be a single 300' shot on a "trig loop". If you use Carlson SurvCE, there is a routine included, where it takes the shots, and then balances the loop at the end, weighting for distance.
Carlson allows you to use multiple sets (forward and reverse) on each shot very easily. I would put that method up against any level any day. (Yes, I know your awesome level is the best thing ever, I like my level too, and it is still the gold standard.) The key is to never change the rod, and stay close enough to avoid heat waves and extreme pointing errors.
Now, if you mean shooting a single forward face shot...that isn't anything but negligence.
Jim_H, post: 373958, member: 11536 wrote: Do you really need to paint things up to be seen from outer space?
Don't even get me started on flagging....
If it is in the deep, dark, vast tract of woods, there is no such thing as too much flagging or too much paint. (Imho).
In the instance above, a good description would be worth more than 90% of the paint used.
But, if he was doing trigs, he intended to be able to see it on the way back through the loop, I assume, so that he could see the TP at the setup when he turned to it. No excuse for defacing property, but a reason for him, perhaps.
He should just run a differential level loop. It's faster, easier, and more accurate. Does he not have a level either?
dmyhill, post: 373965, member: 1137 wrote: Not sure what is meant by "trigging", but I have run many loops that we term, "trig loops". They close very well, typically, unless you fat finger something.
Around here, the relief might require 5 turns to get up a hill that would be a single 300' shot on a "trig loop". If you use Carlson SurvCE, there is a routine included, where it takes the shots, and then balances the loop at the end, weighting for distance.
Carlson allows you to use multiple sets (forward and reverse) on each shot very easily. I would put that method up against any level any day. (Yes, I know your awesome level is the best thing ever, I like my level too, and it is still the gold standard.) The key is to never change the rod, and stay close enough to avoid heat waves and extreme pointing errors.
Now, if you mean shooting a single forward face shot...that isn't anything but negligence.
I agree you can get good trig elevations, using proper procedures. Working solo I do it all the time, but he's not going to get good results taking 1800' shots, especially if his instrument has any calibration error.
Dan Patterson, post: 373993, member: 1179 wrote: He should just run a differential level loop. It's faster, easier, and more accurate. Does he not have a level either?
Trig loops can be just as, or more, accurate than conventional loops. The balancing of foresights and backsights is still required and the legs need to stay about as short as you'd expect on a conventional loop.
The beauty is that you don't need to carry a philly rod and level with you. That being said, a conventional loop, assuming both are done the same way, is faster though. I will give you that.
Kris Morgan, post: 374007, member: 29 wrote: Trig loops can be just as, or more, accurate than conventional loops. The balancing of foresights and backsights is still required and the legs need to stay about as short as you'd expect on a conventional loop.
The beauty is that you don't need to carry a philly rod and level with you. That being said, a conventional loop, assuming both are done the same way, is faster though. I will give you that.
Time to bring out this paper again. "Electronic Total Stations are Levels Too" By Jesse Kozlowski.
This procedure works from experience. Just not as much application now with GPS so available.
Brian Lepore, post: 373945, member: 11478 wrote: I always am torn about the paint debate? After working the last 22 winters in the north east i appreciate fresh paint on a control point that has just been buried under snow. But that is a little much even for me... Now the trigging a elevation that is just silly.
The problem is this isn't a permanent control point. Unless he screwed something up, he'll never be at this site again.
We had a fellow working here that set a BM on a light pole and painted the elevation on it.
The problem was it was not a creosote pole. It was a brand new ornamental light pole. The city didn't approve of that.
trig levels will be fine, if they know what they are doing, and have a bench or two at the start and end, and they check.
It's probably better than most of the elevations gathered with the black box that aren't tied to anything with respect to the FEMA mapping.
5 miles seems awful far for cali,,,,,,,and that being the nearest control? Just how were the FEMA maps generated? sounds like there won't be any meaningful BFE for this site.
Hundreds of thousands of bridges have been built across this country over the last 100 years with no nearby benchmarks. How do you suppose they carried the elevations to those sites? Once trig leveling was an option, it made life tremendously easier in areas with steep grades. Hate to tell you all this but that black box you carry around can be off a bunch of you don't have anything to check it against.
If he was working with an OE-3 chainman recently dispatched from the hall, he probably had to use that much paint for the chainman to find the TBM the next time they need to use it.
Holy Cow, post: 374088, member: 50 wrote: that black box you carry around can be off a bunch (i)f you don't have anything to check it against.
It will still be off, even if you check it; but at least you'll know it's off. Nobody is going to check your work but you. But they damn sure will point their finger at you; when things go south...B-)
