Details for Benchmark: LC0770
N 40° 53.600 W 088° 37.683 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In LIVINGSTON county, IL View Original Datasheet
- Q 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
1.2 MI NE FROM PONTIAC. ABOUT 0.1 MILE WEST ALONG WEST MADISON STREET FROM THE POST OFFICE IN PONTIAC, THENCE 0.6 MILE NORTH ALONG NORTH DIVISION STREET, THENCE 0.55 MILE NORTH AND NORTHEAST ALONG AN ASPHALT PAVED ROAD (OLD U.S. HIGHWAY 66), AT THE CROSSING OF THE WABASH RAIL ROAD, SET IN THE TOP OF THE NORTHEAST END OF THE SOUTHEAST HEADWALL OF A 5 FOOT CONCRETE BOX CULVERT (UNDER THE ASPHALT PAVED ROAD), 20 FEET SOUTHEAST OF THE CENTER LINE OF THE ROAD, 50 FEET NORTHEAST OF THE CENTER OF THE CROSSING OF THE WABASH RAIL ROAD AND 2 FEET BELOW THE LEVEL OF THE ROAD. NOTE-- THIS MARK MAY ALSO BE REACHED FROM THE JUNCTION OF U.S. HIGHWAY 66 AND STATE HIGHWAY 23 IN THE NORTHWEST PART OF PONTIAC BY GOING EAST 0.25 MILE ON STATE HIGHWAY 23, THENCE 0.85 MILE EAST AND NORTHEAST ALONG WEST LINCOLN AVENUE (OLD U.S. HIGHWAY 66).
- 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.