US-34 1917(MacArthur)+1994 Bridges over the Mississippi river at Burlington, IA

1917-1994: (Bridge Hunter; no Historic Bridges; HAER; Satellite)

1994: (Bridge Hunter; John A. Weeks III; Satellite) Great River Bridge

HAER IOWA,29-BURL,7--2

2. OVERALL VIEW OF BRIDGE AND MISSISSIPPI RIVER, FROM WEST RIVER-BANK. VIEW TO SOUTHEAST. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

Significance: After decades of agitating by the citizens of Burlington, local businessman J.A. MacArthur formed the Citizens' Bridge Company in 1915 and erected this bridge, using an innovative financing plan. The structure was taken over by the City of Burlington in 1923 and has functioned as a toll bridge ever since. The MacArthur Bridge is historically significant as a regionally important crossing of the Mississippi River: the source of millions of dollars of revenue. It is technologically significant as the oldest cantilever truss and the oldest highway-only bridge remaining over the Mississippi.

HAER IOWA,29-BURL,7--4

4. THROUGH TRUSS SPANS, FROM WEST RIVERBANK. VIEW TO NORTHEAST. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

 

Bridges Now and Then posted
A January, 1917, look at the MacArthur Bridge over the Mississippi River that, when completed, would link Burlington, Iowa and Gulfport, Illinois. (Library of Congress)
[So there there were two MacArthur Bridges over the Mississippi River, one here and one at St. Louis.]

I wonder if the HAER writer was paid by the page because he included a history of the cantilever bridge design.

The cantilever design and high configuration of the bridge, though greatly different from the railroad bridge at Burlington, conformed closely to general engineering practice of the time and to precedents set by earlier vehicular bridges over the Mississippi. The technique of building out from either end of a bridge and joining at the middle is an ancient one. In principle a cantilevered beam or truss distributes stresses in much the opposite way as does a comparable simply supported structure. Held aloft at both ends by piers or abutments, a simply supported bridge deflects downward toward the middle when loaded so that the lower chord is convex under a positive bending moment. A cantilever bridge, on the other hand, is supported at only one end and must therefore be counterbalanced by a second member extending in the opposite direction from the pier. A cantilever span bends so that the upper surface is convex in a state of negative bending. The distribution of tensile and compressive forces is therefore reversed. In a simple truss the top chord is in compression and the bottom in tension; the top chord of a cantilever truss is in tension and the bottom chord in compression.

The distribution of the bending moment is also reversed. The maximum bending occurs at mid-span on a simple truss and at the anchored end, over the support, on a cantilever. As literal manifestations of stress analysis, trusses reflect this with eloquent simplicity. Polygonal-chorded simple trusses are deepest at the center, placing the greatest cross-section of steel to resist the greatest bending moment. Conversely, the web depths of cantilever trusses tend to be greatest at the piers.

Cantilever trusses built in the 19th century were related to each other more in method of construction than in web configuration, and as a result they displayed a wide array of shapes, especially in the formative years. The first large-scale cantilever bridge built in America was the Kentucky River Bridge of the Cincinnati Southern Railroad, erected from a design by Charles Shaler Smith and L.F.G. Bouscaren in 1876-77.39 Built using mathematically demonstrable but practically untried principles, the bridge was an innovative and dramatic structure - "a work of science without concession," according to architect Louis Sullivan. Other major cantilevers soon followed, with increasingly longer spans. These included the 470'-span Niagara River Bridge [1883] by Charles C. Schneider, the 548* Poughkeepsie Bridge [1888] by Thomas Curtis Clarke, the 551* Tyrone Bridge [1889] by John McLeod, the 660' Red Rock Bridge [1890] by J.A.L. Waddell, the 790' Memphis Bridge [1893] by George S. Morison, and, climactically, the 1800' Quebec Bridge [1907] by Theodore Cooper.4o

By the time the latter bridge was completed, at least 32 major cantilevers had been erected in America, 22 of which exceeded 400' in span length.4i Cantilever bridges typically had three spans: a main center span (comprised of two cantilever arms that held a center suspended span), with an anchor span at either end. These were usually found in through truss configuration, although cantilevered deck trusses were also built with regularity.

Built in locations that made falseworks impractical or that required extremely long spans, cantilevers also had significant drawbacks. They were by nature less rigid than simple trusses, limiting their use primarily to highway bridges.42 They also tended to cost more to erect than simple trusses. Bridge engineer JA.L. Waddell, who had himself designed the Red Rock cantilever, criticized this bridge form harshly, saying:

About the time that cantilevers came into vogue, certain bridge designers entertained a wild idea to the effect that the new type involved some special virtue or feature of excellence or else that St was economic at first cost; because many cantilever bridges were built in places where simple-span structures would have been far better and cheaper. Possibly the thought of establishing an innovation induced some of the designers of those bridges to prefer the cantilever type to that of the simple truss. What a pity it is that such designers did not devote their time and energy to an attempt to introduce the steel-arch bridge into American practice! Had they done so, probably they would have been successful; because there is so often true economy in the arch - besides it is far more aesthetic than either the cantilever or the simple truss. A long-span, cantilever bridge can be made agreeable to the eye by using artistic outlines and a well-studied web-system; and, again, its simple vastness produces a pleasing impression upon the beholder; but a small-span cantilever is ugly and causes a trained intelligence to propound to itself the question "why and wherefore?" without receiving a satisfying answer. 43

Cantilevering suited itself well to bridge construction on the Mississippi River. Congress had required that each bridge over the river be either a low-level, moderate-span structure with a moveable truss over the main channel, or a high, fixed-span bridge with relatively long spans. Faced with severe limitations on the grades of their bridge approaches, railroad engineers almost always designed river-level structures to cross the Mississippi. Additionally, rail traffic tended to be intermittent, allowing the railroads to operate swing-span bridges efficiently. But for vehicular bridges, which carried continuous traffic and which could use much steeper approaches, the engineers preferred fixed spans held high over the river. Cantilevering these structures allowed them to design relatively long, fixed-span trusses that were materially conservant. Further, by eliminating the need for falseworks over the Mississippi's main channel, the engineers could avoid obstructing river navigation and could erect the superstructures largely without concern for the highly changeable conditions on the river below.

[HAER-data, pp13-15]

The report goes on to detail the four cantilever bridges that had already been built across the Mississippi River before this bridge was built. Waddell was the "father" of the lift bridge design. He has been proven right about steel arches because many modern bridges use a tie-arch design. And the new I-74 bridge is using pure steel arches.

The regular approach and anchor arm trusses have to be built with falsework. Are they using the ice on the river as the foundation for the falsework?

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55. Photographic copy of photograph (November 1916; original print in possession of Burlington Public Library, Burlington, Iowa). SUPERSTRUCTURAL ERECTION ON WEST ANCHOR ARM OF BRIDGE, SHOWING FALSEWORKS AND TIMBER TRAVELER. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

But the main span over the navigation channel doesn't need falsework.

HAER IOWA,29-BURL,7--57

57. Photographic copy of photograph (January 1917; original print in possession of MacArthur Coffin, Burlington, Iowa). SUPERSTRUCTURAL ERECTION ON SUSPENDED CHANNEL SPAN OF BRIDGE. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

Terry A via 1994 Bridge Hunter

John Weeks
The bridge was under construction during the 1993 flood. The bridge was above the waterline during the flood, so construction continued during the food. The construction offices were flooded out, so a temporary office was set up in a old semi-trailer. At the peak of the food, the old bridge, the MacArthur, was the only bridge open between the Quad Cities and Saint Louis. The MacArthur was finally shut down for 4 days, not because of issues with the bridge, but from concerns that the vibrations of the bridge would weaken the nearby levees.
The main tower is reported to be 370 from bedrock to the top. I have not found a number for how high the tower is above the waterline. I estimate that it is 300 feet based on measuring photographs.

 

Carol Jeffrey Brokaw posted
Great River Bridge, Burlington IA

One of several photos along the Mississippi posted by Terri Christie
[Note the new BNSF lift bridge in the background.]

Alex Carey posted
Great River Bridge, Burlington Iowa

Angel Binner posted

Angel Binner posted
This week cover photo is credited to Adrian Loewenhagen! Thank you for this amazing picture of the USACE's Dredge Goetz tow! Dennis DeBruler: Without seeing the base of the tower, I could not determine if this bridge tower was at Burlington, IA, or Quincy, IL. But the attachment of the cables to the deck show that this is the bridge at Burlington.

Jess Sherwood posted
A little follow the leader through the fog in pool 19 this morning.
Matt Randall: Patriot, Merrell Colsch and Peggie Louise. Not sure I have the spelling correct on them all.
[Merrell Colsch is correct, but the third must be Peggy Louise. There are many towboats named Patriot.]

 

Jess Sherwood posted
M/v Mary Evelyn, northbound with 2 empties and 2 loads. Pool 19 UMR, Burlington Iowa.
Angel Binner updated

 

Jess Sherwood posted
M/v Serria Dawn with the Gold Cup on the hip. Northbound, pool 19 UMR Burlington Iowa.

0:33 timelapse video @ 0:25