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Caltrans 60's-Era Coordinates
Posted: Sat Jan 15, 2011 10:29 pm
by Jim Frame
I don't know how many hundreds of Caltrans acquisition deeds I've read over the years, but in all that time I've never needed to pay attention to the coordinates given. Today I'm trying to fit a deed to the ground, at least approximately, and all I have so far are the coordinates. However, they aren't making sense to me.
The deed dates from 1965, and cites "California State Zone 2 Coordinates X=2,067,271.34 and Y=430,463.68." It subsequently states that the coordinates are on the "California Coordinate System, Zone 2." Distances, and presumably coordinates, are in feet. Given the date of the deed, I assumed these to be NAD27 values (they're definitely not NAD83 values). However, when I convert to geographic using CORPSCON, I come out 20 or so miles north of the intended location. I hand-cranked it using Special Pub 253 and came up with the same result.
Is there an implementation of CCS27 that I'm not aware of, or some other custom system that Caltrans used back in the day?
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Posted: Sun Jan 16, 2011 11:40 am
by dmi
those values are meters.
Posted: Sun Jan 16, 2011 12:04 pm
by Jim Frame
"those values are meters."
That would put me somewhere in Colorado...
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Posted: Sun Jan 16, 2011 12:46 pm
by dmi
I was wrong they are not in meters, but I can tell you this I am unable to get any type of a reasonable answer with your values. I end up in the ocean, yep all wet here
try zone 0403 and see if that is not mo betta?
Transposition?
Posted: Sun Jan 16, 2011 3:23 pm
by Surveyor826
Y=340,463.68 vs Y=430,463.68
moves it 17 miles south.
My experience with those coordinates is that they are worse than useless.
They imply a precision to the uninitiated that was never intended by originator and will never be found by the resurveyor.
If its all you've got then I suppose you'll have to do something with them, just saying I would diligently search for something better (or maybe I mean more reliable).
Good Luck!
Posted: Sun Jan 16, 2011 5:52 pm
by land butcher
They are definitely in feet, we didn't use metric when I was there in the late 60's early 70s. What you might try doing is just inversing between the coords and use the bearings and distances. A ground to grid adj should not be that hard to find data on, but IIRC under 5 miles the difference isn't much unless you are 3000ft above sea level.
Another thing to remember is that CDH would scale a distance and call it out xxxx.00ft and base everything in the area on that. So adjoining legs to x.xx are +/- who knows how much.
maybe if you
Posted: Sun Jan 16, 2011 8:37 pm
by bruce hall
use what you think the approx NAD83 coord should be, then work back to the stuff that Cal Trans has, maybe a transpostion will show up, which when "corrected" will put you in the right place.
Posted: Sun Jan 16, 2011 10:06 pm
by Jim Frame
The problem is that the deed is tied to the A2 line (the old highway centerline), but the ROW and monumentation maps only show ties to the A3 line (the current freeway centerline). The A2 line is shown on the maps graphically, but there's no mathematical tie between them.
I've got the deed positioned approximately for now, but absent information relating A2 to A3, I'm in a bind.
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Posted: Mon Jan 17, 2011 3:30 pm
by land butcher
Go to CalTrans and their cave. See if you can have someone dig up old control/cadistral//r/w maps or even const plans. The lines had to be tied together before A3 was on the ground.