Saturday, September 11, 2021

1908 UP/MoPac and US-190 Bridges over Atchafalaya River in Krotz Springs, LA

MoPac: (Bridge Hunter; Historic Bridges; Satellite)
1934-1986 US-190: (Bridge Hunter; HAER)
1973(w/b, north side)+1988(e/b, south side) US-190: (Bridge Hunter; Historic Bridges; Satellite)
The 1988 w/b bridge reused the 1934 piers.

The railroad bridge contains the cantilever truss and the road bridges are built with continuous trusses.

MoPac Railroad Bridge


Street View
In the mid-1920s, the Louisiana Highway Commission entered into an agreement to pay the railroad company - at this point, the Missouri Pacific Railroad (Gulf Coast Lines) - $25,000 per year to share the bridge with auto traffic. However, there were delays in constructing the adjacent portions of State Route 7 (now US 190), then known as the Evangeline Highway. As the highway neared completion, the railroad bridge was surfaced with asphalt and opened for auto traffic on September 1, 1930. Auto traffic was discontinued in April 1935 with the opening of the original highway bridge just upstream. [BridgeHunter-MoPac]

 A desire to dredge and expand the capacity of this river required expanding the bridge with a new 721 foot extension. This extension took an unusual form. A three span cantilever structure was built, but unlike most 3 span cantilever bridges, the center span was designed as the anchor span while the end spans were cantilever arms. These cantilever arms each held one of the original fixed 1908 Double-intersection Warren through truss approach spans, turning these former simple truss spans into half-suspended spans. The project took place from 1938-1940. [HistoricBridges-MoPac]

Judging by the trees on the right, the river was running high.

Street View, Apr 2021

Photo by Jeff Dubea via BridgeHunter-MoPac
Taken from a boat trip in October 2017. The US 190 bridges seen in background.

I saved a satellite image to record that they have recently done some maintenance work on the railroad bridge. HistoricBridges-MoPac indicates that the rehabilitation was done in 2019.
Satellite

Travis Gordon posted
August 19, 2021
UP 4014 crosses the Atchafalaya River in Krotz Springs, Louisiana.

PortOfKrotzSprings
[Renaming the road bridge in 2015 to be the "Frank and Sal Diesi Bridge" appears to be a monument to nepotism----father and son were president of the Port Commission.]

PortOfKrotzSprings


1934-1986 US-190 Bridge

HAER LA,49-KROSP,1--1, cropped
1. VIEW, FROM SOUTHWEST, OF ELEVATION - Krotz Springs Bridge, Spanning Atchafalaya River, Krotz Springs, St. Landry Parish, LA

"This bridge is a K-truss bridge and is one of six bridges of this truss type in Louisiana [in 1983]. The K-truss type is virtually non-existent outside of Louisiana." The War Department "insisted that all channel piers be carried down to a minimum depth of one hundred feet below low water and also insisted that no mattress protection work be constructed around these piers on the bed of the river. Their reasons for these requirements were based on the supposition that the Atchafalaya River would be used as a relief floodway for the excess water from the Mississippi River and would, therefore, be subject to additional widening and deepening due to the steep hydraulic gradient. This is especially true at Krotz Springs, where the river had increased its cross sectional area approximately 100$ in the 40 years before the bridge was constructed....The type of piers that were constructed were cylindrical in shape and extended approximately 140 feet below low water. As this death was beyond the limits to which men can safely work under the pneumatic process of pier sinking, and it was most desirable to penetrate the river bed by this method to a depth beyond where obstructions such as sunken logs, barges, etc., might be encountered, a combination of pneumatic and open sinking was employed. In this way, the piers would be carried to a depth of approximately 100 feet below low water where the roof of the air chamber would be removed and the pier carried down to the depth desired by open dredging methods. The natural ground elevation at the site of the two back piers was approximately 30 feet above low water elevation and, consequently, these two piers were sunk to a penetration of approximately 170 feet in material, varying from gumbo clay through silt and sand to gravel. One of these piers was sealed with a tremie when the water elevation was about 33 feet above low water stage or, in other words, at a depth of approximately 173 feet." The K-truss is not as efficient as the Warren truss. [HAER-data] The work expended on the piers paid off because they were reused for the 1988 bridge.

HAER LA,49-KROSP,1--4
4. VIEW, LOOKING SOUTH, OF WESTERNMOST SPAN

Jared comment on BridgeHunter-1973

HAER LA,49-KROSP,1--9
9. VIEW, LOOKING EAST, OF WEST APPROACH
[The 1973 span is on the left.]


Frank and Sal Diesi Bridge

A John T. Dauzat photo via BridgeHunter-1973
[This is looking east so the 1973 bridge is on the left and the 1988 bridge is on the right.]

I used this view of the southern span from the northern span to confirm the above view is looking east. Because of the levees, you can't get decent street views from the side roads.
Street View

Another view looking east. The truss of the 1988 bridge is unusual because it used the old piers. Historic Bridges describes these two bridges even though they are not historic as an example of how truss bridges have become ugly. As a taxpayer, I don't mind the simplified look of modern trusses. At least they are trusses instead of cable stayed bridges.
Courage and The Wheel of Progress, Jun 2019

A view looking West.
Betsy R. via FourSquare



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