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Astoria-Megler Bridge

Astoria-Megler Bridge

Primary Photographer(s): Nathan Holth

Bridge Documented: September 3, 2018

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Key Facts

Facility Carried / Feature Intersected
Oregon Coast Highway (US-101) Over Columbia River
Location
Astoria: Clatsop County, Oregon and Pacific County, Washington: United States
Structure Type
Metal Continuous 28 Panel Rivet-Connected Warren Through Truss, Fixed and Approach Spans: Metal 12 Panel Rivet-Connected Polygonal Warren Through Truss, Fixed
Construction Date and Builder / Engineer
1966 By Builder/Contractor: American Bridge Company of New York, New York and DeLong Corporation and Engineer/Design: George Stevens, William A. Bugee, and Ivan D. Merchant

Technical Facts

Rehabilitation Date
Not Available or Not Applicable
Main Span Length
1232 Feet (375.51 Meters)
Structure Length
21677 Feet (6607.15 Meters)
Roadway Width
28 Feet (8.53 Meters)
Spans
3 Main Span(s) and 188 Approach Span(s)
NBI Number
07949A009

Historic Significance Rating (HSR)

Bridge Documentation

View Archived National Bridge Inventory Report - Has Additional Details and Evaluation

This bridge is large, long, and unique. From south to north, the bridge can be roughly divided into three sections: The curved south/Astoria approach ramp, the enormous continuous main through truss spans, a low-level causeway, and lastly a slightly elevated series of simple span through trusses at the northern/Megler end. The causeway is the longest section of the bridge and it creates an unusually long distance between the two truss sections of the bridge. This distance is difficult to capture in photos, so videos of crossing this bridge are included on this page.

The bridge is an iconic landmark of Astoria, and the bridge has been seen in movies filmed in Astoria. Despite its relatively young age, the bridge is historically and technologically significant for its overall length as well as its main span length. The design of the main spans are also unusual. In fact, this bridge's main spans are very misleading in appearance. Looking at the central/navigation span of the three main spans, towards the center of the bridge the repeating "V" pattern of the Warren truss is interupted for one panel, and at this location, pins are visible. This is usually a dead giveaway for a cantilever truss bridge with a suspended span. And for this bridge, during construction, that is indeed how the bridge functioned, as a cantilever truss with cantilever arms holding this suspended span in the center. However, when erection was completed, this suspended span was riveted to the cantilever arm turning the pin-connected hanger system into rigid, riveted connections. This change resulted in the truss functioning as a continuous truss, rather than a cantilever truss. The suspended span no longer "hangs" from cantilever arms, it is instead from an engineering standpoint all part of the same truss in terms of force distribution. This differs from a traditional cantilever truss because in a traditional cantilever truss the suspended span is literally like a completely independent, separate truss bridge that is hanging from the cantilever arms. Some details of this unusual design which accommodated a specific construction and erection procedure, can be seen detailed in these original erection plans.

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Photo Galleries and Videos: Astoria-Megler Bridge

 
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Bridge Photo-Documentation
Original / Full Size Photos
A collection of overview and detail photos. This gallery offers photos in the highest available resolution and file size in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer
View Photo Gallery
Bridge Photo-Documentation
Mobile Optimized Photos
A collection of overview and detail photos. This gallery features data-friendly, fast-loading photos in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer
View Video
CarCam: Northbound Crossing
Full Motion Video
Note: The downloadable high quality version of this video offers better 1080 HD detail. Streaming video of the bridge. Also includes a higher quality downloadable video for greater clarity or offline viewing.
View Video
CarCam: Southbound Crossing
Full Motion Video
Note: The downloadable high quality version of this video offers better 1080 HD detail. Streaming video of the bridge. Also includes a higher quality downloadable video for greater clarity or offline viewing.

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