Details for Benchmark: LC0721
N 40° 39.100 W 088° 46.700 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In MCLEAN county, IL View Original Datasheet
- T 246
- 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)
|01/01/1960 by CGS (MONUMENTED)
|01/01/1961 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1961
1.4 MI N FROM LEXINGTON. ABOUT 0.45 MILES WEST ALONG WEST MAIN STREET FROM THE POST OFFICE IN LEXINGTON, THENCE 1.0 MILE NORTHEAST ALONG U.S. HIGHWAY 66, AT THE JUNCTION OF AN ASPHALT PAVED ROAD SOUTH (OLD U.S. HIGHWAY 66), 100 FEET SOUTHEAST OF THE CENTERLINE OF THE NORTHBOUND LANE OF U.S. HIGHWAY 66, 306 FEET NORTHEAST OF THE CENTER OF THE JUNCTION OF U.S. HIGHWAY 66 AND OLD HIGHWAY 66, 36 FEET NORTHWEST OF THE NORTHWEST RAIL OF THE SOUTHBOUND TRACK OF THE GULF MOBILE AND OHIO RAILROAD, 9 FEET SOUTHWEST OF A GUY WIRED TELEGRAPH POLE, 2.7 FEET NORTH OF A METAL WITNESS POST, 2 FEET ABOVE THE LEVEL OF U.S. HIGHWAY 66, AND SET IN THE TOP OF A CONCRETE POST PROJECTING 2 INCHES.
- 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.