Details for Benchmark: HT1855
N 37° 49.667 W 122° 12.717 (NAD 83)
Coordinates may not be exact. Altitude is VERTCON and location is SCALED. (more info)
- In ALAMEDA county, CA View Original Datasheet
- M 1253
- Marker Type:
- bench mark disk
- abutments and piers of large bridges
- Probably hold position/elevation well.
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Documented History (by the NGS)
|01/01/1974 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1974
2.7 KM (1.70 MI) SOUTH FROM OAKLAND. 1.7 MILES SOUTH ALONG STATE HIGHWAY 13 FROM THE JUNCTION OF STATE HIGHWAY 24, AT A PEDESTRIAN OVERPASS, IN TOP OF THE EAST CORNER OF THE CONCRETE FOUNDATION FOR THE SOUTH-WESTERN MOST STEEL LEG FOR A SUPPORT PIER, 23.5 FEET SOUTHWEST OF THE CENTERLINE OF THE SOUTH BOUND LANES OF THE HIGHWAY, 0.5 FOOT EAST OF THE EAST CORNER OF THE CONCRETE FOUNDATION FOR A STEEL LEG, ABOUT 3 FEET HIGHER THAN THE HIGHWAY.
- 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- The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) The vertical order pertains to the superseded datum.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.