NGS Geodetic Leveling Class

Jimmy Cleveland, post: 448349, member: 91 wrote: Any advice

Fly. Don't drive.

I have only taken the "office" portion of the class (long story), but from what I have heard from folks who have attended the full class...

It is awesome, and probably the best "training session" you will ever take. You will [probably] never think about leveling the same way again.

Loyal

Without invar, temps, fixed legs, and bi pods isnƒ??t that just 3rd order?

mvanhank222, post: 448374, member: 8673 wrote: Without invar, temps, fixed legs, and bi pods isnƒ??t that just 3rd order?

That's one of the things he'll learn in the class.

I took it several years ago, and I found it useful. I've done a few Second Order Class 2 projects since then, and having the classroom experience definitely helped.

probably so, but that is what the client spec'd out. It saved us a ton of money on equipment.

Thanks for the info. I'll probably drive, just because I'm a pretty big fella, and I don't think I'll be too comfortable in economy class. Plus I don't think I can get back to the airport on Friday to catch the flight back in time.

BUMP

Not to pile on, but your statement "The differences are we are not using invar rods, measuring temperatures, fixed leg tripods for the level or the bipods for the rods" is like saying I had an operation, the surgeon was pretty good except he never went to medical school and this was his first time with a knife.

You will definitely learn to proper way to do geodetic leveling at the class. Well worth the expense (class is free, time and travel costs are not).

Using a good quality digital level, the standard composite rod, and decent turning points you can get loop closures on the order of a couple of thousandths per mile. While it would be better still with invar rods, bipods, etc., etc. one has to wonder why and when it would be necessary to do so. Perhaps if one was building a super-collider or something...Just saying that the digital levels are a game changer and I hope the procedures allow for that.

Thanks for the comments. We are following the specs the client wrote. They could not justify to their superiors the need for the true first order procedures, (time and expense). We are using 150' FS and BS, and are achieving excellent results with our new digital level. Our closures are less than 0.01' for over 2 miles of level runs. The client was very happy with the first round of observations.

I agree with the digital level statement Mark made. They are indeed a game changer. I want to learn the proper procedures, and even though we are using modified specs, I can adhere to the proper procedures as closely as I can. I also want to be more familiar with the office portion of the process, because we are using Windesc for the descriptions, recovery notes, etc. I am processing the *.dat files in Spectra Precision Survey Office.

This is the first project of this type we have done, and having the proper training may open the door for more projects of this type in the future.

If your level is capable of taking a waving read if so use it if not a rod level will work. I have seen misleading closure numbers due to compensating errors. Also I am assuming you are using survey pro you can set parameters on what restrictions you want based on NGS procedures in the leveling module.

I will agree that in a small area, relatively flat, a digital level (geodetic quality) with a good rod will achieve good results.

The main difference between second order class I and second order class II (other than 60 m versus 70 m sight lengths) is the requirement for rod calibration and also temperature observations at each setup. While I think the rod calibration is a good idea, the temperature observations are, in my opinion, not necessary unless you are going really far on a constant up or down grade, and even then only marginally useful. First order, yes. Second order, not so much. Just my opinion. We do both second order Class I and second order class II work each year

Thanks. We are using Trimble DiNi level, and the on board data collection. Per the client's specs, our BS and FS must be balanced within 10' for the total turn, and using the measure option, we are balancing less than two feet per sight.

We are using (2) folding Trimble level rods with the handles and factory attached level bubbles.

A +1 on the digital levels- an order of magnitude easier to obtain outstanding results. However, they're NOT 100% correct all the time... all too easy to get yourself into "appliance operator" mode by failing to verify. Only had one bust with them in the 13-plus years, though...

The Trimble (Zeiss) rods are much better, in my opinion, than the Leica rods (used many years ago). Both made by the same manufacturer (Nedo), but to different specs/designs. The Leica rods seemed to develop a "looseness" over time at the joint, which caused a very small gap to be there between high and low rods. We would replace those every year (back in the 90's, maybe improved since then). I have had my 4 m folding Zeiss rod since 2003 or so, never had a problem with it. And we check it against the invar rods. I have three 3 m invar rods, a 4 m standard rod, a 1 m fiberglass rod, and a 0.50 m invar rod.

I will be at the Friday class (river crossings). I attended the geodetic leveling class in the past, and a river crossings class, but the river crossings class was the "old" way. The NGS has come out with a spec for river crossings using total stations rather than levels.

The NGS Supplement to Chapter 4 of NOS NGS 3, Geodetic Levelling.

Yes, I read it when it first came out. I wonder if anyone has a fabricator lined up that can make the targets and mounts?

I attended the class, and it was well worth the trip. The NGS staff was very knowledgeable, and very friendly. I would recommend anyone that has an opportunity to take a class the the training center to do so. One of, if not the best training sessions I have ever attended.

Thank you to the NGS staff for putting on the class.

Posted by: Scott Zelenak

The NGS Supplement to Chapter 4 of NOS NGS 3, Geodetic Levelling.

I expected to see Jesse's name in the author list.?ÿ He seems to have done as much as anyone to popularize leveling with a total station.