I guess I am just curious about things. The bridge in the photos below is the old Milwaukee Road railroad bridge across the Missouri River at Chamberlain, SD.
There are at least three different types of bridge used here, possible four since I could not see the long stretch on the far end very well.
Why are only two truss sections needed? Why not build the entire bridge like the type in the third photo? What is that type of bridge immediately following the truss sections that goes down and why that design? Maybe just three transitional spans?
Obviously a guvment project!
🙂
Loyal
First glance indicates it may be due to the differnece in spans.
Well, I don't have all of the answer, but I think I do have a part of it.
It was related to clearance for boat and ship traffic. And, lock and dams. And elevated bridges.
Back then, they had big plans for America.
Nate
The Two Main Tusses Allow River Traffic
The deck trusses beyond provide longer spans and allow smaller boat traffic. The longer spans allow fewer piers in deeper water.
The deck girders are in shallower water areas and more shallow piers are more economical.
One thing I remember from an early college structural engineering class was that the pier costs were about equal to the span costs.
Paul in PA, PE, PLS
I learned a long time ago; don't question engineers. They seem to always have an agenda that is best left alone. Occasionally, one must question THEM, but for the most part, it's best just to let it ride......
Cheers,
Radar
Poor design. Obviously this bridge complex will win no awards. Engineers are like anyone else, some are good and some are not so good.
First Clue
Observe the difference in distance between pier placement.
Bridge Construction - why not
Ok, I'll be the devils advocate.
Does a professional land surveyor ever question a professional engineers decisions?
Or perhaps the bureaucrats decisions that pay the bills?
...I'll just leave it at that
There's a railroad bridge near where I grew up that deteriorated to the point that the center overhead truss sections were unsafe. The railroad removed the existing spans and brought in scavenged spans from an abandoned track in West Tennessee. The scavenged spans were of identical design and length and were placed on the existing piers with no modifications.
News stories at the time indicated that this was possible because the spans were of a standard design. Maybe the railroads took this standardization to the point that they were building bridges with "off the shelf" parts depending on site conditions.
Built by Corps of Engineers
Found this article which states it was built by the COE in 1953.
