"In your opinion do you think field checking/adjusting rod & tribrach bubbles and plummets would minimize the benefit of this method to a negligible level?"
Yes, it would, if that regular adjustment actually happens. Without the redundant measurements you have no proof in the raw data - aside from traverse closures - that the equipment was in good order at the moment the measurements were made. By rotating the rods and tribrachs, and doubling angles and distances, you have that proof in the raw data.
Myself, I don't collimate or adjust rods and tribrachs as often as I recommend that others do. But I do dogmatically double measurements while rotating target rods - and examine the splits. As long as those splits remain good, I know that things are as they should be.
I regularly check and adjust all my gear, especially before running control.
My goal is to always do all the cross ties available, but do them twice. Though if I am on a limited time budget I will choose the tie over a redundant observation. I am in a somewhat unique position as most of my work is done in house with contractors who don't fully understand what it is I do for them so they leave me be when I say I need two days of turning rounds before beginning a project.
(And am usually met with blank stares when I ask others in my field, of construction surveying, how often they check their poles. I had fun conversations with two different coworkers in the last few weeks who didn't realize that peanut prims could be rotated in their housing. One swore to me that it was only true in the one face. I attempted to teach the other one that this was a quick way to test the bubble on a layout prism but I don't think the lesson stuck.)
I take care of my equipment and procedures. What bothers me is people who sneak up behind me to ask what I am doing. It's really none of their business and I really need to concentrate.
When some of these busy bodies need to chat or need to know... they are wasting my time. Meanwhile the equipment may be going out of level or I may just mess up from being distracted.
Sometimes I want to ask them where they work so I can go bother them about which side of the desk they ar placing their paper clips.
While I agree that Sidewalk Superintendents can be annoying and distracting, surveyors in their neighborhood is very much their business. Try it when you have your city's logo on the side of your truck.
Don’t ya know that when people bother you that’s an opportunity for you to make more money. Just tell them to smile and you will take a picture of them with your fancy camera lol. I was doing a survey on the Memphis zoo early in my I man days. We had an old Lietz set B and a SDR 24 data collector. I was looking at a BS triple glass with a barb pole on top candy cane. My LS was in the elephant pen and told me to check my BS. We use to set the azimuth not zero. So I swung around dialed in and looked at my angle compared to azimuth we had in the book. It didn’t match so I did an inverse long hand making sure I didn’t write the wrong azimuth down. Looked again didn’t see the bs so turned to it and it was bopping along. The kindergartners on a field trip had all grabbed a leg and was just walking with it talking about a moment. See all we could see over a walk and over to it was the candy cane and a little of the top glass on that 3 glass triangle prism set up. Of course one had to have a map to get around to it lol . When kids came by us we had to pretend we were taking pictures and video of them. Even some of the moms were fixing there hair as they approached us.
6. Make sure your instruments tripod is of high quality and all fasteners are tight.
IMHO (which is 100% correct), this is #1. Every single messed up traverse I have dealt with was traced to poor support for the instrument.
Also, field checking bubbles and targeting for tribrachs is easy if you use a pass through tribrach with a total station with a plummet and carriers with a bubble and plummet for the prisms.
I like that. It’s like having a Cadillac riding on bad tires and warped rims. No matter how accurate and precise an instrument is if what it’s setting on is junk it’s all for nothing.
While I agree that a stable tripod is critical for high precision measurement I kind of object to the use of the word "tight". Because it tends to lead to "overtight". Which makes things wear out quickly . I encourage my guys to tighten these things using their fingertips only. Those screws need to be snug, but not tight.
"Fingertip tight."
That's how I was taught and I'm regularly surprised that others (apparently) didn't receive the same lesson.
The to tight and the not tight enough. I was taught when adjusting tripods that you should be able to pick it up parallel with ground and it’s slowly fall back down nice and smooth. The leg that is. To tight it just hangs in the air to lose it falls rapidly. Of course that was using all wood back then.
Speaking of to tight some like to white knuckle tighten the instrument or target down. That leads to warping the head of the tripod. Plus makes it a bear to unscrew the darn thing. I had one guy he had it torqued Dow so bad once I had to get channel locks to get it undone.
Yeah, over tightening is one of the first things I teach an apprentice when showing them how to take care of the equipment. Another big one is to always put the equipment in their cases when moving between setups. Also, is this all 360 prisms? I’ve had good luck with some as long is you have a flat face to the TS when setting the BS or shooting in a control point. The vertical is what I usually have issue with but running levels to tighten up the vertical seems to correct that.
Ditch the bi-pod. If you are truly worried about accuracy of your control, then utilize stable back sites and fore sites. And that is not a bi-pod, especially since most just rattle around in the back of the truck. Besides, using tri-pods is actually quicker, you need to set one on every point anyway, why not do it to begin with.
As tribraches and prism carriers, I'll second or fourth the recommendation carriers with the integrated plumet. It is easy in the field to determine if they are in adjustment, and just as easy to adjust. They cost about $200 more but the difference is almost made up for in the cost of the tribrach. The extra couple of bucks is well worth it.
🖕
It's nice to work in the big country where never a traverse is heard.
I don't double all of my observations with the (expressed) intention of cancelling out any systematic error in the plummets/poles. My intent is to add redundancy. While the additional observations are done the same day, so they don't have different meteorological conditions, by resetting the tribrachs/poles they are, to some extent, independent measurements. My goal is to introduce random error so that it can then adjusted out (if that makes any sense).
I stumbled upon this practice by accident when I was in school and doing a StarNet pre-analysis on our second-year field project, a large control traverse. By copying and pasting another set of our planned observations into StarNet I saw a dramatic improvement in the confidence of our points, however this is only true, in my opinion, if all targets/instruments are reset to make the observations independent. I have been using this practice for my control ever since.
On a related note, when I am coming off of primary control, with a resection for example, if I have time, I will perform the observations twice (with targets/instrument rotated in between), the mean of the two observations is the MPV (Most Probable Value).
