Details for Benchmark: JC1162
N 38° 42.033 W 090° 10.900 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In MADISON county, IL View Original Datasheet
- 3 LOCK 27 RM
- Marker Type:
- survey disk
- massive structures with deep foundations
- Most reliable and expected to hold position/elevation well.
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Documented History (by the NGS)
|Unknown by DOD (MONUMENTED)
|01/01/1981 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1981
IN GRANITE CITY. IN GRANITE CITY, AT THE U.S. ARMY CORPS OF ENGINEERS LOCK NUMBER 27 NEAR THE SOUTHWEST END CONTROL BUILDING OF THE SOUTHEAST WALL OF THE SOUTHEAST LOCK CHANNEL, 8.23 METERS (27.0 FEET) NORTHWEST OF THE NORTH CORNER OF THE BUILDING, 0.95 METERS (3.1 FEET) SOUTHEAST OF THE SOUTH-EAST EDGE OF THE SOUTHEAST LOCK CHANNEL. THE MARK IS ABOVE LEVEL WITH TOP OF LOCK.
- 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 June 1991.
- 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.