The History and Historical Significance of the Eagle Point Bridge
Condensed from the HAER report by J.R. Manning
The Dubuque and Wisconsin Bridge was the fifth Mississippi River bridge to Iowa that was built for vehicular traffic rather than for rail. It had no provision for pedestrians. It was more popularly known as the Eagle Point Bridge, because the west portal was in the Eagle Point neighborhood of Dubuque. It was built for the Dubuque and Wisconsin Bridge Company, a private operator that charged a 10¢ toll in both directions of travel. The bridge was designed by Edward Clapp Shankland, who was also the chief engineer for the 1893 Columbian Exposition in Chicago. It was the last survivor of those original five bridges but it was lost in 1983.
The bridge consisted of eight spans just downriver from from Lock and Dam #11. It could be said that Lock and Dam #11 are upriver from the location of the Eagle Point Bridge, since it predated the dam by almost 20 years. It was situated on the far north end of Dubuque and was mounted at the end of Rhomberg Avenue on a limestone bluff that was reinforced with concrete. The bridge had two unique features. One was that the first four and last three spans were through trusses while span five was a deck truss. It was commonly known as the "upside down" span. The other unique feature was a bend on the east end of span five. The first five spans crossed perpendicular to the river, probably to facilitate river navigation, but there was no location on the Wisconsin side for the bridge to land without the angle.
The west portal was located at approximate GPS coordinates 42.53700, -90.64490 and the east portal at approximate GPS coordinates 42.53900, -90.63880.
The west side of the river had a stone bluff that was used as the starting point for the bridge. The Wisconsin side of the river is an area of islands, sloughs and backwaters that was prone to flooding before the dam was built. The bridge could have been skewed to reach the solid approach on the Wisconsin side but the angle would have narrowed the navigable channel between the piers. The only option was the change of direction between the fifth and sixth spans.
The Eagle Point Bridge was constructed in four stages, which seems to be an unusual statement for a structure that must be complete to be usable. In 1901-1902, four steel spans were built from the west shore that were connected to Wisconsin by a wooden trestle that was about 1900 feet long. A fifth steel span was added in 1907 to replace a troublesome wooden span, completing an all-steel bridge across the main navigable channel of the river. The bridge was realigned in 1922, and the rest of the wood approach was replaced with steel spans in 1936. The first five spans used creosote wood for decking, the 1936 spans had concrete decks. The creosote wood decks were replaced with open mesh steel decking in 1949, the last major project performed on the bridge.
The first four spans, built in 1901-92, were two Pratt through trusses and two Pennsylvania through trusses. The fifth span, added in 1906-07 was a Baltimore deck truss. The final three spans, added in 1935-36 were Pratt through trusses. There was also a short deck plate girder span on the east shore that served as an approach.
There were three toll houses on the Iowa side of the river. A 10¢ toll was charged in both directions and collected on the Iowa end of the bridge.
Eastbound traffic climbed a slight grade on the first span, just slightly over 4%. The deck was level over the main spans across the navigation channels, then made a gradual descent of just under 5% to the Wisconsin side of the river.
Counting from west to east, piers 1 through 4 were cross-braced, concrete filled, steel columns. Pier 5 was added in 1906 to support the Baltimore deck truss and was similar in design to the first four. When the final spans were added in 1935, piers 6-8 were built as twin battered concrete columns.
Span #1 was an 8 panel, pin connected Pratt through truss, 191.3 feet in length. The creosote wood deck was replaced with steel open mesh decking in 1949. The west portal had a name plate that read, "Dubuque and Wisconsin Bridge 1901." On the west end of the span, the north end post had a designers' plate that read, "E.C. and E.M. Shankland." The south end post held the builder's plate that read, "Toledo Bridge Co. Linehan and Molo."
Span #2 and #3 were virtually identical, 20 panel camelback Pennsylvania through trusses, 378.3 feet in length. They also had creosote wood decks that were replaced with open mesh steel decking in 1949.
Span #4 was an 11 panel Pratt through truss that was 198 feet in length. The creosote wood decking was replaced with open grate steel decking in 1949. Since this was the original east end of the bridge, the end posts had designers' and builder's plates identical to the plates on the east end of span #1.
Span #5 was a pin-connected Baltimore deck truss that was added in 1906. It was 324 feet in length and had the same creosote wood deck that was replaced with open mesh steel decking in 1949. A builder's plate was located on the inside of the north top chord, near the west end. It read, "Built by A.Y. Bayne & Co. Minneapolis, Minnesota 1907."
Spans #6, 7 and 8 were added in 1935-36. They were virtually identical, 8 panel Pratt through trusses skewed 26° 8' 15" from the pier axes. The spans were 160 feet in length and had concrete decks. A builder's plate was located on the northeast end post of span #8 that read, "Built by Worden-Allen Co. Milwaukee, Wis."
Highways 151 and 61 were moved to a new freeway alignment in 1983 when the new Mississippi River US 151/61 Bridge was built about a mile downriver of the Eagle Point Bridge. The Eagle Point Bridge was demolished shortly after, marking the end of the historical vehicle bridges into Iowa that were built in the late 19th and early 20th Centuries.
For more detailed information about this bridge, follow the link below to the HAER listing. The complete report, from which this condensed report was made, is availble at that location.
