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Details for Benchmark: AT1408

N 29° 55.950 W 089° 59.883 (NAD 83)

Altitude: 19.72

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In ORLEANS county, LA View Original Datasheet
Designation:
LMS 50
Marker Type:
traverse station disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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Documented History (by the NGS)

01/01/1977 by USE (MONUMENTED)
01/18/1991 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1991 0.4 KM (0.2 MI) WESTERLY ALONG PATTERSON ROAD FROM ITS JUNCTION WITH CHELSEA DRIVE IN ALGIERS, AT THE SOUTH EDGE OF A ROAD ON TOP OF THE MISSISSIPPI RIVER LEVEE, 81.2 M (266.4 FT) WEST OF THE SOUTHWEST END OF A PIER WALKWAY, 24.1 M (79.1 FT) NORTH OF THE CENTER OF THE ROAD, 18.6 M (61.0 FT) NORTH OF A UTILITY LIGHT POLE, 4.0 M (13.1 FT) ABOVE THE ROAD CENTER, AND THE MONUMENT IS 0.1 M (0.3 FT) BELOW THE GROUND SURFACE.
02/07/1995 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1995 (GAS) 0.4 KM (0.25 MI) NORTHWESTERLY ALONG PATTERSON ROAD FROM THE JUNCTION OF CHELSEA DRIVE IN ALGIERS, 80.2 M (263.1 FT) WEST OF A SET OF STEPS LEADING TO A LEVEE, 23.6 M (77.4 FT) NORTHEAST OF THE ROAD CENTER, 18.5 M (60.7 FT) NORTHEAST OF UTILITY POLE NUMBER 7 WITH 4 GUY CABLES, 5.6 M (18.4 FT) SOUTHWEST OF THE SOUTHWEST EDGE OF A CONCRETE PORTION OF THE LEVEE, 1.3 M (4.3 FT) SOUTHWEST OF THE CENTER OF A LEVEE ROAD, AND THE MONUMENT IS RECESSED 0.3 M (1.0 FT) BELOW THE LEVEL OF THE LEVEE ROAD.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in December 1996.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (G = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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