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Hi Ben,
Good to hear from you again.
The map projections are identical. The geodetic coordinates of the underlying stations shifted a bit from the prior realization for stations with GPS observations
in the NGS data holdings. Many of our benchmarks got new coordinates because of the GPS-on-benchmark campaigns, plus the many occupations done by CTDOT and myself+students over the years. But, old trig stations and such didn’t get updated.
CT will need to decide whether to change our SPCS in 2022. The shift in horizontal coordinates is a bit more than a meter, which is somewhat awkward. So, we’ll
see.
Hope that helps,
toM
-------------------------------------------------
Thomas H. Meyer, Ph.D.
Professor of Geodesy
University of Connecticut
Dept of Natural Resources and the Environment, U-4087 W.B. Young Bldg,
rm 325
1376 Storrs Road
Storrs, CT 06269-4087
http://www.nre.uconn.edu/Faculty_and_Staff/Meyer.php
Follow @UConnNRE: 
From: Unmoderated discussion list for Connecticut GIS Users [mailto:[log in to unmask]]
On Behalf Of Michael Ray
Sent: Thursday, October 05, 2017 1:05 PM
To: [log in to unmask]
Subject: Re: [CTGIS-L] NAD83 (2011) CT State Plane Projection
I was going to go back and reference some of the things I learned from Ben Smith and then I looked and saw it was........ you. Long time, no see.
I have not noticed a difference. From what little research I've done, it has more to do with the control elements of the datum. If you had a feature class of geodetics, they would perhaps be impacted.
"As part of continuing efforts to improve the NSRS, on June 30, 2012, NGS completed the National Adjustment of 2011 Project. This project was a nationwide adjustment of NGS "passive" control (physical marks that can be occupied with survey equipment, such as
brass disk bench marks) positioned using Global Navigation Satellite System (GNSS) technology. The adjustment was constrained to current North American Datum of 1983 (NAD 83) latitude, longitude, and ellipsoid heights of NGS Continuously Operating Reference
Stations (CORS). The CORS network is an "active" control system consisting of permanently mounted GNSS antennas, and it is the geometric foundation of the NSRS. Constraining the adjustment to the
CORS optimally aligned the GNSS passive control with the active control, providing a unified reference frame to serve the nation's geometric positioning needs."
That is, unless I've completely misunderstood what I just read and that the change would have a cascading effect. Good luck!
On Wed, Oct 4, 2017 at 4:28 PM, Smith, Ben - NRCS, Tolland, CT <[log in to unmask]> wrote:
Hi All,
Besides the name, does anyone know if there is supposed to be a difference in ArcMap between the NAD 1983 (2011) StatePlane Connecticut FIPS 0600 (US Feet) and NAD 1983 StatePlane Connecticut FIPS 0600 (US Feet) projections? I tried testing it with and without transformations, and there seems to be nothing different.
Thanks,
Benjamin Smith, Hydrologist
USDA, Natural Resources Conservation Service
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