Details for Benchmark: HS4117
N 37° 42.050 W 121° 51.483 (NAD 83)
Coordinates may not be exact. Altitude is VERTCON and location is SCALED. (more info)
- In ALAMEDA county, CA View Original Datasheet
- U 1257
- Marker Type:
- bench mark disk
- retaining walls, concrete ledge, etc.
- May hold, but of type commonly subject to surface motion.
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Documented History (by the NGS)
|01/01/1974 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1974
6.8 KM (4.25 MI) EAST FROM DUBLIN. 4.25 MILES EAST ALONG INTERSTATE HIGHWAY 580 FROM THE JUNCTION OF FOOTHILL ROAD AT DUBLIN, 0.45 MILE WEST OF THE JUNCTION OF EL CHARRO ROAD, 43.5 FEET SOUTH OF THE SOUTH MOST CENTERLINE OF THE EAST BOUND HIGHWAY LANES, IN THE TOP OF THE SOUTH CONCRETE HEADWALL OF DOUBLE CONCRETE BOX CULVERT 17.16, 12.5 FEET WEST OF THE EAST END OF THE HEADWALL, AND ABOUT 1.5 FEET LOWER THAN THE HIGHWAY LANES.
- The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
- The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.
- The geoid height was determined by GEOID99.