Information for Strong-Motion Station
San Juan Bautista - Hwy 101/156 Overpass
CGS - CSMIP Station 47315
Earthquakes recorded by this station
(Station Photograph - click to enlarge)(Sensor Layout - click to see PDF File)
Latitude 36.8619 N
Longitude 121.5796 W
Elevation (m) 122
Site Geology Alluvium
Vs30 (m/sec) 363 (inferred)
Site Class C/D
Remarks Site information sources
No. of Spans6
Plan ShapeStraight with skew.
Total Length321' (97.8m). Bridge spans range from 33.5' (10.2m) to 68.5' (20.9m).
Width of Deck28' (8.5m)
Construction Date1958
Instrumentation1977 & 2002. 12 accelerometers on the bridge. 3 accelerometers at a free-field site.
Superstructure TypeWelded steel girders with concrete diaphragm added during the retrofit supprted by rocker bearings. Seat abutments with catcher beams and integral wing walls.
Substructure TypeConcrete bents with rectangular columns. 2 columns per bent. Infill walls were added between the columns during the retrofit.
Foundation TypeSpread footings.
RemarksThe bridge was first instrumented by CSMIP in 1977. After the retrofit, the bridge was re-instrumented in 2002 under the interagency agreement between Caltrans and DOC.