Details for Benchmark: LC0754
N 40° 49.750 W 088° 40.083 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In LIVINGSTON county, IL View Original Datasheet
- U 248
- Marker Type:
- bench mark disk
- light structures
- Mark of questionable or unknown stability.
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Documented History (by the NGS)
|01/01/1961 by CGS (MONUMENTED)
|DESCRIBED BY COAST AND GEODETIC SURVEY 1961
3.3 MI SW FROM PONTIAC. ABOUT 3.3 MILES SOUTHWEST ALONG U.S. HIGHWAY 66 FROM ITS JUNCTION WITH STATE HIGHWAY 116 IN THE SOUTHWEST PART OF PONTIAC, AT THE JUNCTION OF AN EAST-WEST GRAVELED ROAD, SET IN THE TOP OF THE NORTHEAST END OF THE NORTHWEST HEADWALL STONE AND CONCRETE PIPE CULVERT UNDER THE GULF MOBILE AND OHIO RAIL ROAD, 99 FEET SOUTHEAST OF THE CENTER LINE OF THE NORTHBOUND LANE OF U.S. HIGHWAY 66, 8 FEET NORTHWEST OF THE NORTHWEST RAIL OF THE SOUTHBOUND TRACK OF THE GULF MOBILE AND OHIO RAIL ROAD, 92 FEET SOUTHWEST OF THE CENTER OF THE CROSSING OF THE SOUTHBOUND TRACK AND AN EAST-WEST GRAVELED ROAD, 2 FEET BELOW THE LEVEL OF THE TRACK AND ABOUT LEVEL WITH THE HIGHWAY.
- 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.