RE SH 121 Gas Line points (2)
Keith
I just called, but missed you. I spoke with survey again, and they
said that converting out of the grid coordinate system and into a
surface coordinate system is standard practice and that we would
certainly want to do that for design purposes. He also said that TxDOT
does the same thing, so it was necessary to match up with their data.
For the City’s GIS which is on a grid coordinate system, it would be a
simple task of applying the scale factor in reverse and giving the City
that file for incorporation into the GIS. He said that we generally
don’t have to do this because many city’s systems are already scaled out
of the grid coordinate system. Neither is wrong, they are just
different.
On a side note, we did not run into this problem for the Sandy Lake
pier shots, because Delvin received the points, asked survey to add them
to the drawing for us, and then sent me the resulting file. Survey took
care of the conversion for us, and we didn’t notice the difference.
I hope this clears this up. Our guys would be happy to discuss this
further if a more technical explanation is needed. We’ll make sure to
provide files that have been re-set to the grid coordinate system upon
completion of the project. That will allow the files to drop in without
any problems.
Thanks.
Casey McBroom, P.E.
Project Engineer
17304 Preston Road, Suite 1340
Dallas, Texas 75252
214.461.9867 Phone
972.900.5733 Mobile
214.461.9864 Fax
cmcbroom@tnpinc.com <mailto:cmcbroom@tnpinc.com>
From: Keith Marvin [mailto:KMarvin@coppelltx.gov]
Sent: Friday, September 13, 2013 11:09 AM
To: Casey McBroom
Cc: Chris Schmitt; Michael Garza; Scott Latta; Kevin Rubalcaba
Subject: FW: SH 121 Gas Line points
Casey,
See the attached point file. We believe that TNP is using a different
coordinate system than we use, and that is causing this discrepancy. If
you are aware of this, and are doing it intentionally to make our
drawings work with the SH 121 widening project, then we can apply some
sort of conversion to our data collection to rectify the situation.
If this is an inadvertent use of a different system, then we will ask
you to correct the drawings to shift your work into the appropriate
coordinate system.
Keith Marvin, P.E.
City of Coppell
972-304-3681
From: Kevin Rubalcaba
Sent: Friday, September 13, 2013 11:04 AM
To: Keith Marvin
Cc: Scott Latta
Subject: SH 121 Gas Line points
These include the most recent points we took today.
-kevin