Open Traverse closing method
You could save on the walking next time and do a diamond traverse. It makes a closed loop and you only have to go one direction???
I can’t visualize how you only have to go one direction. We haven’t started the traverse yet. It will go a quarter mile north, a quarter mile east, and a half mile north. The traverse corridor is tight for the first two directions; it runs down two-lane country roads. The last corridor runs along a wide berm. We’ll side shoot five quarter corners and some property corners along the way.
MHMade a little sample
Set up the instrument on Rod Pt1. Set 2 control pts a foot apart as far as line of sight allows. Backsite the control on the left (8) and turn to the control on the right(2). This will be your closing angle. Get distances at this time also.
Backsight on the rod at Pt 1. Station on 2 foresight on 3/7. Collect backsight distance, angle and foresight distance to 3. Set up on a control pt (8) 1 ft from Pt 2. Backsight 3/7 and turn back to Pt 1. Setup on 3/7 backsight 2 get angles and distances to 4. Set Pt 6. While still setup on 3/7 backsite 6, turn angle and distances back to 8. Forgot to mention you will have 2 backsight nails when looking back at 2 and 8 so dont get them confused????
Set up on 4 backsight 3/7 rurn to 5 set up on 6 one foot from 4, backsight 5 turn angles and diatances to 3/7. Set up on 5 backsight 4 turn angle to 6.
This should give you a closed loop and you have only had to hike it once. (if you have be a ride at the other end????)
Let me know if i screwed something up in there its been a long day????
Oh yeah dont foeget to tie the rod from pt 3/7????
All kidding aside, I initially agreed with management on the validity of their argument, but the next day I reverted back to my original position on the subject. I mean really, how often do we have the convenience of checking into a published NGS azimuth mark? How often can we check into a known plat line? If the beginning and ending pairs of GPS points of an open traverse are properly post-processed they should be perfectly valid. Management is now standing firm on a single fifteen minute observation per point for traverse points and section corners.
MH
They want to create some stability. Have some rules for the crews to follow.
Still, why do they think an azimuth mark is the best control?
Still, why do they think an azimuth mark is the best control?
Those are my words. They just want something official like an NGS point.
MH
I’m probably in the minority here, but I have never been a fan of the diamond traverse. It’s only useful to me if my project absolutely requires a traverse closure (can count those projects on one hand), or for some weird reason I am unable to perform a least squares analysis.
Instead, I’ll just perform two station setups (and two rounds of observations) at each control point, relevelling and recentering in between those two setups. This also gives me an opportunity to verify heights, or change them for an additional check, if vertical is critical. My preference is to switch backsight and foresight on the second setup to close the horizon, which gives me an immediate check on the first set of observations. If the horizon closure, distance or vertical deltas are unacceptable, it’s easy to re-measure before moving up.
Still only requires one trip through the open traverse, gets you plenty of redundancy – without adding more unknown stations like a diamond traverse – and there’s less chance of a blunder on sighting the wrong point immediately next to another one. Not to mention more blunder checks period.
Throw everything into a correctly weighted LSA and whammo, not only do you get most likely values for coordinates, but proper error estimates as well.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman
Tape the distances 2-8, etc. for additional checks.
.Sounds like an efficient way to get redundancy. Re-centering (and releveling if not automatic), not just measuring twice, seems an important part of it. I, too, fail to see the advantage of the diamond traverse over a double-measured (walking single direction) traverse.
.I haven’t done one in years because we mark timber lines with open traverse pin to pin. We close loops when setting a section corner but i think it makes less error to traverse to spots that see long shots across canyons as opposed to dozenzs of short turns in the S@%&.
I need a trial of this javad thing??? id make a video repeating one of my jobs and it might settle this pretty quick if it sits on 2 brass caps and it agrees with my line posts down in the S%@$ between them???
Oh yeah, boss said the new gun showed up this weekend. Team Nikon????
A video’d trial of any brand of GPS in those woods would be great.
@field-dog exactly… and what happens with the new modernization and NGS doesn’t even set or maintain physical monuments?
@jed yep… and using a “diamond” and “square” orientation for the flagging for the sight nails helps differentiate… or different color flagging.
NGS hasn’t set any monuments in years, not around here anyway. I think that the last hurrah in that department was around 1990.
hat happens with the new modernization and NGS doesn’t even set or maintain physical monuments?
The new definition of official elevation will be GNSS tied to CORS, plus a gravity model to convert ellipsoidal height to orthometric. If you want a physical mark, that will be up to you.
.Hope that Nikon works out, I found them great for deep woods work…compact, light and pretty tough too. Think I was using the Nivo…
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman
@amksyr I think that’s new info in this thread. From what I understand it’s not possible to adjust an open traverse without the first and last stations both known. There would be no information to adjust to. If adjustment is needed, I’d guess you have to close it by traversing back to the POB or make them known by taking static GNSS shots on each and conforming them to a known datum.
dd
“Open” or “route” traverses are what we call a WAG or some derivation of such. IF you didn’t have any need to be in a certain place at the end, it may not matter.
You can get some idea of how close your WAG might be by running the traverse backwards, but geometry is not your friend on this sort of traverse. If you need it TIGHT, you have to use other options. Typically, we would run it forward and reverse, carrying vertical, and combine with a GPS observation on each end. If you can turn angles to a natural target from stations along the way, all the better. At that point Microsurvey’s Star*Net is a great tool to analyze the network.
-All thoughts my own, except my typos and when I am wrong.
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