Details for Benchmark: ME1728
N 41° 40.733 W 087° 59.983 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In COOK county, IL View Original Datasheet
- PBM 115
- Marker Type:
- 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)
|Unknown by CGS (MONUMENTED)
|01/01/1947 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1947
AT LEMONT. AT LEMONT, COOK COUNTY, AT THE ATCHISON, TOPEKA AND SANTA FE RAILWAY BRIDGE OVER THE CHICAGO DRAINAGE CANAL, IN THE WING WALL OF THE SOUTH ABUTMENT, IN THE TOP OF THE WEST END STONE OF THE SECOND COURSE ABOVE THE GROUND, 2.2 FEET FROM THE WEST END OF THE STONE, AND 1.1 FEET BACK FROM THE FACE OF THE WING WALL. THE TOP OF A COPPER BOLT LEADED VERTICALLY IN THE STONE AND SURROUNDED BY THE LETTERS USPBM.
- 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.