CONSTRUCTION-MP590--Joel's Southern Pacific in the Cascades

Construction

MP 590

At Milepost 590, the SP makes it's final crossing of the middle fork of the Willamette River. This bridge can be seen from Highway 58 near Hampton.

August 25, 1952 saw the completion of the final bridge need for the Merdiain Dam relocation project. This bridge was built with an E-72 loading factor, made up of 6 spans. Below is a list of the spans starting with span #1 on the east, (Eugene) end of the bridge:

Span #1 - 80' Through Plate Girder
Span #2 - 150' Through Truss Span
Span #3 - 250' Through Truss Span
Span #4 - 150' Through Truss Span
Span #5 - 80' Through Plate Girder
Span #6 - 80' Through Plate Girder

View from HWY 58. The original route can be seen behind the bridge.

The present location of the bridge is actually the second of 2 routes that were studied to avoid a large landslide area on the left bank of the river. During 1949, 5 core drill samples were studied and found that the present location was the most feasible. This new route required a line adjusment, which lengthened the bridge.

Building the peirs and abutments. A portable batch plant was constructed at the job site, shown below.

Construction of the falsework has been completed. The 3 Through Truss Spans will then be assembled on top of the falsework. After completion, the falsework is then removed.

Girders 5 and 6 have been erected at the west end of the bridge. The final stage was to erect the 3 Through Truss Spans. In the photo, there are 3 grades evident. The new route under construction, the original route just to the right, and the temporary grade to the left that connects the Original route to the new route. This temporary grade was built so that fill could be placed from the hillside, then later removed.

During construction of the bridge, errors in the materials were found. This photo shows one of the bridge rockers warped. This was due to a flaw in the casting. The 2 photo thumbnails below show flaws in the rivet holes, and the factory installed rivets.

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