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Details for Benchmark: HS2886

N 37° 20.750 W 121° 54.267 (NAD 83)

Altitude: 74.72

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In SANTA CLARA county, CA View Original Datasheet
Designation:
B 112
Marker Type:
bench mark disk
Setting:
pavements (street, sidewalk, curb, apron, etc.)
Stability:
Mark of questionable or unknown stability.

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*** HS2886 RESEARCH ***

  • SAN JOSE WEST QUADRANGLE (7.5 minute) from 1953 shows Polhemus Street meets W Taylor at a bridge over Guadalupe River
  • Some time between 1953 and 1961 Polhemus Street was renamed to W Taylor so there was no longer a junction of two
    street names on the same road.
  • This is evidenced in the 1961 San Jose West Quadrangle (7.5 minute)
  • The benchmark is highly likely to be BM 76 on the 1961 San Jose West map.
  • The original bridge over the Guadalupe has been replaced by a larger bridge.
  • Google maps confirms what appears to be the original bridge in 1993 historical view
  • Google maps shows no bridge over the Guadalupe in 2000 historical view
  • Google maps shows the current bridge in 2009 historical view.
  • Scouting the trail underneath the new bridge shows no evidence of the old.
  • This benchmark should be considered destroyed as the original bridge is no longer in existence.
[Photos:]
photoOver head view in 1993 showing original bridge.
photoover head view in 2000 showing the bridge removal
photoToday's Taylor Street bridge

Documented History (by the NGS)

01/01/1932 by CGS (MONUMENTED)
01/01/1954 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1954 AT SAN JOSE. AT SAN JOSE, AT THE JUNCITON OF WEST TAYLOR AND POLHEMUS STREETS, AT A CONCRETE BRIDGE OVER GUADALUPE RIVER, IN THE TOP OF THE SOUTH END OF THE EAST CONCRETE GUARDRAIL, 30.2 FEET EAST OF THE CENTER LINE OF POLHEMUS STREET, AND ABOUT 3 1/2 FEET HIGHER THAN THE STREET.
01/01/1967 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1967 RECOVERED IN GOOD CONDITION.
11/21/1988 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1988 RECOVERED IN GOOD CONDITION. A NEW DESCRIPTION FOLLOWS. 0.2 KM (0.10 MI) SOUTHWESTERLY ALONG WEST TAYLOR STREET FROM THE JUNCTION OF GUADALUPE PARKWAY IN SAN JOSE, IN THE SOUTHWEST END OF THE SOUTHEAST CONCRETE ABUTMENT GUARDRAIL OF A STREET BRIDGE SPANNING THE GUADALUPE RIVER, 9.2 M (30.2 FT) SOUTHEAST OF THE CENTERLINE OF THE STREET, AND 1.1 M (3.6 FT) ABOVE THE LEVEL OF THE STREET.
02/01/1990 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1990 RECOVERED IN GOOD CONDITION.

Control Text

  • 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 February 1993.
  • 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.

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