Details for Benchmark: HY1172
N 38° 45.333 W 082° 59.600 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In SCIOTO county, OH View Original Datasheet
- W 120
- Marker Type:
- bench mark disk
- massive structures
- Probably hold position/elevation well.
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Documented History (by the NGS)
|01/01/1943 by CGS (MONUMENTED)
|01/01/1967 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1967
0.8 MI N FROM PORTSMOUTH. ABOUT 0.8 MILE NORTH ALONG THE NORFOLK AND WESTERN RAILWAY FROM THE STATION AT PORTSMOUTH, 252 YARDS NORTH OF MILEPOST N 608, SET ON THE TOP OF THE EAST END OF THE NORTH STONE AND CONCRETE ABUTMENT OF A 15-FOOT CONCRETE BRIDGE, 90 FEET NORTH OF THE EXTENDED CENTER LINE OF CLARE STREET, 8 FEET EAST OF THE EAST RAIL AND 1 FOOT BELOW THE LEVEL OF THE TRACK.
- 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. WARNING-Repeat measurements at this control monument indicate possible vertical movement.
- 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.