Details for Benchmark: NC0671
N 42° 14.017 W 079° 46.800 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In ERIE county, PA View Original Datasheet
- ORTON RM 1
- Marker Type:
- reference mark disk
- massive structures
- Probably hold position/elevation well.
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Documented History (by the NGS)
|01/01/1961 by CGS (MONUMENTED)
|DESCRIBED BY COAST AND GEODETIC SURVEY 1961
2.9 MI NE FROM NORTHEAST. TO REACH THE REFERENCE MARK FROM THE JUNCTION OF STATE HIGHWAY 89 AND U.S. HIGHWAY 20 AT THE SOUTHEAST CORNER OF THE PARK IN NORTH EAST, GO SOUTHEASTERLY ON U.S. HIGHWAY 20 FOR 2.9 MILES TO THE JUNCTION OF INTERSTATE 90 AND THE MARK ON THE LEFT AT THE SOUTHEAST CORNER OF THE OVERPASS OF THE WEST BOUND LANE OF INTERSTATE 90. IT IS 16.3 FEET EAST OF THE APPROXIMATE CENTER OF THE WEST BOUND LANE OF INTERSTATE 90 AND 3.4 FEET NORTH OF THE SOUTHEAST END OF BRIDGE. IT IS SET IN A DRILL IN THE CURBING OF THE WEST BOUND LANE OF INTERSTATE 90 AND PROJECTS ABOUT 6 INCHES ABOVE THE SURFACE OF THE GROUND.
- 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.