Saturday, March 23, 2019

O.K. Allen 1936-2015 Bridge over Red River in Alexandria, LA

(Bridge Hunter; Satellite)

The truss bridge in the background of this construction photo is one of the better photos I have seen of this bridge.

Jonathan Iley posted two photos with the comment: "9310 American & 3900 Manitowoc."
Jonathan Stephen Mahoney 9310 was a hell of a crane to hang steel with too.


Dennis R Franz Sr Near Lafayette, Louisiana.
Joseph Herbaugh What do they call they shoring for the pour?
Dennis DeBruler If you are talking about the two brown ovals, they are cofferdams. They are built by driving lock-type steel sheet piles into the riverbed and then pumping the insides dry. The piers will be built inside these. When the piers are done, the pilings are removed.
Since it will change, I record the satellite image.

The first thing that caught my eye was that the cranes are rather old.

The second thing that caught my eye is that the truss is a K-truss. The HAER for US-190 in Krotz Springs states: "This bridge is a K-truss bridge and is one of six bridges of this truss type in Louisiana. The K-truss type is virtually non-existent outside of Louisiana." But that bridge was gone by 1988 and now this one is gone.

The third thing that caught my eye, and what motivated me to write these notes, is that they are using cofferdams built with "lock-type steel sheet piles." I thought the industry is transitioning to driving a set of big pipes, mucking them out, and then filling them with rebar and concrete.

Red River US 71 Bridge
Posted November 22, 2009, by Cliff D (clif30 [at] hotmail [dot] com)This bridge is scheduled to be replaced and demolished as a part of the TIMED project, according to various sources.
I find it interesting that this bridge can receive such a poor rating (3.5 out of 100) yet is still allowed to carry traffic at high volumes on a daily basis. Several other bridges listed on this website have better ratings and have been closed to vehicle traffic.
[Bridge Hunter]

[Without the piles of metal pipes, that would have been a nice view of the old bridge. It is still a pretty interesting view.]
TheTownTalk (Photo: Melinda Martinez/

[The reference link is broke.]

The 1936 bridge "is one of the last existing examples of the classic "K" truss fixed span bridge design, with a 24-foot clear roadway path and a 500-foot clear center span with concrete and steel deck truss approach spans. The bridge carries well over 20,000 vehicles daily - one lane of traffic in each direction. Steel bridges like the O.K. Allen Bridge have proven expensive to maintain - due to the need for painting - and widening such bridges is cost-prohibitive." The replacement bridge was contracted for $82.9m. "With this replacement project, the main channel of the Red River is to be bridged by a continuous steel girder unit consisting of three spans of 300 feet, 400 feet and 300 feet for a total length of 1,000 feet. Additionally, two new bridges being constructed over the Kansas City Southern railroad tracks will each have a 40-foot clear roadway width designed to carry two lanes of traffic. The new steel span is made of weathering steel which does not require painting. The approach spans are being constructed using 72-inch deep Bulb-T pre-stressed pre-cast concrete girders with the total length of bridge being 3,015 feet." "In anticipation of the completion of the project, 18-wheel trucks were prohibited from using the O.K. Allen Bridge starting in August of 2014, in order to enforce weight limits. The northbound span of the Curtis-Coleman Bridge has been completed, and opened to two-way traffic in March, 2015. Demolition of the O.K. Allen Bridge is now [July 29, 2015] underway and construction of the southbound bridge structure is progressing." [acppubs]
I noticed that the generic term for Corten steel is "weathering steel."

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