Details for Benchmark: LC0668
N 40° 38.983 W 088° 59.933 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In MCLEAN county, IL View Original Datasheet
- A 172
- Marker Type:
- bench mark disk
- set into the top of a round concrete monument
- May hold, but of type commonly subject to surface motion.
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Documented History (by the NGS)
|01/01/1954 by CGS (MONUMENTED)
|01/01/1969 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1969
6 MI S FROM EL PASO. ABOUT 5.95 MILES SOUTH ALONG THE ILLINOIS CENTRAL RAILROAD FROM THE STATION AT EL PASO, 128 FEET NORTHWEST OF THE CENTER OF A CROSSING OF THE RAILROAD AND A PAVED ROAD, 94 FEET WEST OF THE WEST RAIL, 48 FEET NORTH OF THE CENTER LINE OF THE ROAD, 41 FEET SOUTHWEST OF A TELEPHONE POLE, 34 FEET NORTHWEST OF A TELEPHONE POLE, 3 FEET EAST OF A FENCE, 1.0 FOOT NORTHWEST OF A METAL WITNESS POST, ABOUT 1 1/2 FEET BELOW THE LEVEL OF THE TRACK, AND SET IN THE TOP OF A CONCRETE POST WHICH PROJECTS 3 INCHES ABOVE THE SURFACE OF THE GROUND. SEC 4, T25N, R2E
- 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.