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Isthmus Slough Bridge

Photos 

Isthmus Slough Bridge

Photo taken by Historic American Engineering Record

View photos at Library of Congress

BH Photo #138151

Map 

Facts 

Overview
Through truss bridge over Isthmus Slough on FAS A-396
Location
Coos County, Oregon
Status
Replaced by a Concrete Box Girder Bridge in 2004
History
Built 1955, Replaced 2004
Builder
- P. Mervyn Stephenson (Bridge Engineer)
Design
The Isthmus Slough Bridge is significant as a good example of the bascule bridge type. This bridge is unique within the Oregon context at it is the only known bascule structure that utilizes a block and tackle lifting mechanism, as opposed to the more common motorized lifting mechanism. The lack of motorized technology distinguishes this structure within Oregon's context of moveable bridges. The Isthmus Slough Bridge is also significant as a late example of the bascule type within Oregon, as it is only one of three bascule spans built after WWII.
(HAER OR-144 - Isthmus Slough Bridge)
Dimensions
Length of largest span: 85.0 ft.
Total length: 686.1 ft.
Deck width: 24.0 ft.
Vertical clearance above deck: 14.1 ft.
Recognition
Eligible for the National Register of Historic Places
Approximate latitude, longitude
+43.30083, -124.20861   (decimal degrees)
43°18'03" N, 124°12'31" W   (degrees°minutes'seconds")
Approximate UTM coordinates
10/401969/4794931 (zone/easting/northing)
Quadrangle map:
Coos Bay
Inventory numbers
OR 02300A (Oregon Dept. of Transportation structure number)
BH 29928 (Bridgehunter.com ID)

Update Log 

  • April 20, 2009: Posted HAER photos
  • December 4, 2008: Updated by Michael Goff: Updated Status

Sources 

  • Mike Goff - michael [dot] goff [at] hotmail [dot] com
  • HAER OR-144 - Isthmus Slough Bridge
  • Douglas Butler