Control Bust

The job is in state plane, and the scale factor is 1.000000,( both jobs are ) I also asked them are they shooting on a scale of 1.00000 they said yes. I did not watch them set control but I did see them set up their GPS and get out their total station I asked the foreman was they using their TS and he said yes. I'm using Leica and they use Trimble but that should not matter. I triple-checked everything like prism constant etc... I shot this both with my TS07 and TS16, just to make sure it wasn't the new gun. Long shots 950' Im out 0.15' and short shots 250' Im out give or take 0.07', just giving you more info... Thanks

Is anyone else having the same issue? Have you talked to the survey company? Just have them double check their data. Tell them you're having troubles matching what they provided. Any company worth a salt should not get offended and defensive and work with you to find a solution. They could have busted a prism constant. A common constant of -30mm is very close to 0.1'.

Errors of that magnitude suggest an issue with scaling of state plane.

"The job is in state plane, and the scale factor is 1.000000"

It is very unlikely that the correct scale factor is exactly 1 - if you, in fact, have state plane coordinates. I smell a problem here.

I'm not sure you're speaking the same language as the control surveyor.

Are you reducing your measurements by a combined factor to get your distances on the plane?

At .15 in 950 feet that would be a combined factor of .999842 which is a smallish number. 158PPM.

250 feet is too short of a distance to glean much, but if you're always short or always long that should indicate how to "get on" the control.

Does .99984 relate closely to the combined factor for your location?

There are a few things to consider:

1. Ground to grid as indicated by a few other replies to your question. Go to the NGS' Finding Survey Datasheets at https://geodesy.noaa.gov/datasheets/ and search for the nearest NSRS horizontal control point. Check its State Plane Coordinates information where it will show the Combined Factor (CF) which takes into account the point's elevation in addition to the grid scale factor. If you area at approximately the same elevation, then you can use the CF to reduce your ground distance to grid and compare to the control information. If your project elevation is appreciably different than the NSRS points, you can compute you own CF.

2. No measurement is exact - theirs or yours. (a) If they ran a least squares adjustment to create the control information, they should have expected errors (eg, error ellipses) for the points. From that can be computed the expected error in the distances between control points. (b) Your measured distance error is affected by: Total station centering, target centering, and the Manufacturer's Stated Accuracy for the instrument. The combined error may not be large (not in the ±0.10 ft range) but it is a contributing factor. You can see an example computation at http://jerrymahun.com/index.php/home/open-access/46-v-distance-determination/192-chap-f-edm?start=7

If everyone had their ducks in a row, then your reduced to grid distance with its uncertainty should fall within their grid distance with its uncertainty.

Here is one of their reports stating the scale factor at the top of page

I seem to remember LV in general having a CSF pretty close to 1.

If the other job was fine, and also in SPCS grid (scale of 1), and in roughly the same geographic area....I'd wager they screwed up something during observation or adjustment.

0.07' in 250' is a lot.

When I do a grid-to-ground localization with our GPS GS18 and Field Genius software, the combined scale factor is 1.0000849 something close to that, I don't have it on me at this moment.

When doing the grid to ground, I'm just trying to get the GPS to read at a scale factor of 1.0000

So my GPS points line up with the TS points

Noone else has been shooting on the job yet

One more question, when I was using the Leica TS07 I was using the field Genius for Android Software, now with the TS16 I have to use the Captivate software, when using the Leica Captivate and set up using known back sight it won't let me zero out the gun on the known back sight method, or I don't know where or how to set it. For you, Leica guys using Captivate what is your go-to setup method and how do you zero the gun? Thank you

I'm not sure I understand State Plane at a scale of 1.00000. If it is State Plane coords, I wouldn't then say with a scale of 1.0000. That should be implicit. If they are state plane coords that have been modified to ground so that a scale factor of 1.0000 can be used then I would say they are modified State Plane coords and provide the scale factor I used to modify them to ground. I looked at a combined factor for the Ely area at 6900" elevation and it is .99959968. In this area if you were using State Plane coords and shooting ground distances you would expect to shoot a distance longer than the State Plane inverse by that proportional amount indicated by the combined factor.

I looked at a combined factor for the Mesquite area at 1800' and it is 1.00004070. In this area shooting a ground distance would be shorter than the State Plane inverse. You don't say if you are missing long or short. Tell us where you are and we can give you the combined factor for the area. it sounds to me like you are using State Plane coords instead of State Plane coords modified to ground. No one should design or build construction projects using a coordinate system that is not scaled to ground.

5857 East Flaming Road Las Vegas, NV 89122

The Survey does not want to work with me, because they want to do all the layout, I am here to do layout off of survey control, but I feel strongly like the lie to me, etc... I asked if they are shooting in at a scale to 1 and they just say yes

Have you checked the data using GPS to find consistency in their apparent errors?