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Preparing for the 2022 datum

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Jitterboogie
(@jitterboogie)
1,000+ posts Supporter

@leegreen 

When I was recently at las Cruces, we did exactly that and the survey team provided the BM TBM etc for the alignment and then project control.

Was pretty leading edge esp for a municipality of that size.

Takes buyin from the whole team which we definitely had.

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Posted : January 13, 2022 12:23 pm
leegreen
(@leegreen)
1,000+ posts Member

@Jitterboogie

It saves $$, therefore an easy "buyin" for sure.

This post was modified 1 week ago by leegreen
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Posted : January 13, 2022 12:35 pm
FL/GA
(@flga-2-2)
5,000+ posts Supporter

Can anyone explain to this ancient surveyor the necessity of constantly changing datums? 😎 TIA

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Posted : January 14, 2022 9:17 am

Bill93
(@bill93)
5,000+ posts Member

It probably doesn't matter which datum you use to lay out house lots.  But consistency in the larger picture is important. The average surveyor now has measurement capability that is better than the self-consistency of the present datums.

Of particular importance, subsistence has made NAVD88 problematic in many areas and the 2022 datum will allow creation of consistent flood plane data.  Also, the rate of destruction of bench marks means and the spacing of the old level runs means that there are many areas where it is difficult to find one, and thus get good and consistent elevations.

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Posted : January 14, 2022 9:53 am
Norm Miller
(@norm)
500+ posts Member

@flga-2-2 

>NAD 83 is non-geocentric by about 2.2 meters.
>NAVD 88 is both biased (by about one-half meter) and tilted (about 1 meter coast to coast) relative to the best global geoid models available today.
These issues derive from the fact that both datums were defined primarily using terrestrial surveying techniques at passive geodetic survey marks. This network of survey marks deteriorates over time (both through unchecked physical movement and simple removal), and resources are not available to maintain them.

In other words the new datum is more closely tied to satellite orbits making fewer calculations needed to transform GNSS observations to biased and disappearing ground control. 

This post was modified 1 week ago by Norm Miller
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Posted : January 14, 2022 10:12 am
FL/GA and Rover83 liked
Rover83
(@rover83)
500+ posts Member
Posted by: @flga-2-2

Can anyone explain to this ancient surveyor the necessity of constantly changing datums? 😎 TIA

Tectonic plate motion, local motion, improved modelling of the earth, more precise observations of both passive and active marks, improved projection parameters, software and hardware improvements, to name a few.

We also kept kicking the can down the road when it came to adopting the global reference frame as our geodetic basis, which honestly has caused a lot of confusion and no shortage of screwed up datasets.

Posted by: @norm

In other words the new datum is more closely tied to satellite orbits removing all the calculations needed to transform GNSS observations to biased and disappearing ground control.

Exactly. I for one am happy that we're finally going to have a global basis, and active control defined in 4D.

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Posted : January 14, 2022 10:30 am
FL/GA liked

FL/GA
(@flga-2-2)
5,000+ posts Supporter
Posted by: @bill93

It probably doesn't matter which datum you use to lay out house lots.  But consistency in the larger picture is important. The average surveyor now has measurement capability that is better than the self-consistency of the present datums.

Thank y'all, as B93 mentioned house layouts are simple (30 years worth) but I never considered the geodetic aspect. Thanks again! 😎 

Still alive, still learning and love it.

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Posted : January 14, 2022 1:55 pm
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