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Details for Benchmark: BU1470

N 31° 01.240 W 087° 32.343 (NAD 83)

Altitude: 227.89

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

Location:
In ESCAMBIA county, AL View Original Datasheet
Designation:
X 409
Marker Type:
bench mark disk
Setting:
abutments and piers of large bridges
Stability:
Probably hold position/elevation well.

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Documented History (by the NGS)

01/01/1955 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1955 2.8 MI W FROM ATMORE. 2.8 MILES WEST ALONG THE LOUISVILLE AND NASHVILLE RAILROAD FROM THE STATION AT ATMORE, ABOUT 0.35 MILE WEST OF MILE POST 624, IN THE TOP OF THE NORTH END OF THE WEST ABUTMENT OF U.S. HIGHWAY 31 BRIDGE OVER BRUSHY CREEK, 16 FEET NORTH OF CENTER LINE OF HIGHWAY, ABOUT 20 YARDS SOUTH OF TRACK, 1 FOOT NORTH OF CONCRETE BANISTER AND ABOUT 3/4 FOOT ABOVE LEVEL OF BRIDGE FLOOR.
05/12/1987 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1987 THE STATION IS 4.0 KM (2.5 MI) SOUTH ALONG U.S. HIGHWAY 31 FROM THE RAILROAD OVERPASS AT ATMORE, 5.3 METERS (17.5 FT) NORTHWEST FROM THE CENTER OF HIGHWAY 31, SET IN THE SOUTHWEST ABUTMENT OF BRIDGE OVER BRUSHY CREEK AND 0.3 METER (1 FT) ABOVE HIGHWAY 31. DESCRIBED BY K.R.W., TYPED BY E.D.W.
02/18/1997 by BDE (GOOD)
RECOVERY NOTE BY BASKERVILLE DONOVAN INCORPORATED 1997 (RB) RECOVERED AS DESCRIBED.

Control Text

  • The horizontal coordinates were established by GPS observations and adjusted by the National Geodetic Survey in January 1998.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in June 1991.
  • The X, Y, and Z were computed from the position and the ellipsoidal ht.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The ellipsoidal height was determined by GPS observations and is referenced to NAD 83.
  • 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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