Bridge No. L-5573
Encyclopedia
The Bridge No. L-5573, also known as the Clinton Falls Bridge and Old Mill Bridge, is a historic Pratt through truss steel
bridge
that spans the Straight River
in Clinton Falls Township, Steele County, Minnesota. The public bridge was placed on the National Register of Historic Places
(NRHP) on January 25, 1997.
, pin-connected steel Pratt through truss structure on concrete
and limestone
abutment
s. The overall dimension of the combined substructure
and superstructure
is 125 feet (38.1 m) by 22 feet (6.7 m).
The superstructure is eight panels and includes a floor system made up of 3 inches (7.6 cm) by 12 inches (30.5 cm) treated timbers on 5 inches (12.7 cm) steel I-section stringer
s which are themselves supported by 12 inches (30.5 cm) steel I-section floor beams
. These beams are fastened to the hip verticals with rivet
ed plates and are riveted directly to the intermediate posts, except for one exception: the first post to the east on the south side is welded to the floor beam with a steel plate set eight inches off center; it is uncertain whether this was a repair or a correction of the design as it was being built. Both top and bottom lateral bracing consists of eye rods stabilized at intersecting points with bolted plates. The top chords, end posts, and intermediate posts are channels with riveted cover plates and lacing bars. The hip verticals are double forged eye rods, while the diagonals are double punched eye bars. The counters are turnbuckle
s. The lateral and portal struts are double angles to which portal bracing (double angles) is connected with ledger plates. The portal struts and bracing make up a riveted unit which is bolted to the end posts. 2 inches (5.1 cm) by 6 inches (15.2 cm) wooden guard rail
s are boted to the bridge with angle sections. A builder's plate is fastened to the top portal struts at each end of the bridge.
The concrete, poured onto the limestone abutments and wing wall
s, was added in 1975; other than that, the bridge is essentially in original condition. A fragmentary abutment, which supported an earlier, shorter structure at the same crossing, is located west of the current east bank abutment.
in the county. That mill and its associated dam were listed together on the NHRP from 1986 until they were removed in 2004.
The current bridge is the second bridge built on the site. In 1867, the people of Steele County voted to build a covered bridge
for approximately $3000. It is believed that some of the abutments for that original bridge were used in the present one. In May 19, 1894, the Clinton Falls Township Board voted to build an "iron bridge" with steel joist
s over the river and awarded a contract to the George E. King Bridge Company of Des Moines, Iowa
. The existing covered bridge was demolished in late September 1894. The old bridge was removed by September 27 and a large force began rapidly installing the new structure in its place. The new bridge was finished on October 2, 1894 and was described as "all iron and steel, except the planks and railing." On December 3, 1894 the Steele County Board agree to assume 60% of the cost of the bridge. The bridge was considered as an option for planners of the Jefferson Highway
.
Over the decades, Clinton Falls Township faded away: the town's mill, school, church, store and post office all closed and the bridge became one of the few historic structures left. In 1970, the bridge was declared unsafe for vehicles and in need of repairs estimated at $3000. With few residents living on one side, the Township Board elected to close the bridge to all traffic. The plan was met with vehement opposition from residents on the isolated side of the bridge. The situation was resolved when Reuben Kaplan, the owner of a business in nearby Owatonna, Minnesota
, donated the money to repair the abutments and cement work and put in new wood planks and railings.
It carried Township Road No. 95 before it was closed to traffic again in 1994, its 100th year. Minnesota Department of Transportation
made the decision after inspectors discovered that some of the steel stringers supporting the bridge deck had become dangerously thin from rust
. Inspectors estimated repairs would total $105,981 to bring the bridge up to a five-ton standard weight limit. Local residents formed the Save the Clinton Falls Bridge Committee to raise money to repair the bridge as well as push for historic preservation. Concerned residents contacted the Minnesota Historical Society
, which vetted their claims and hired a historian to prepare its NRHP nomination, which was successful. As of October 2010, the bridge remains closed to traffic.
arch construction was preferred for short spans. Initially, wrought iron
and wood were used in combination on Howe truss configurations. These bridges peaked in popularity in the 1870s. All-iron construction started to appear with bowstring arch bridges, but by the 1880s the pin-connected Pratt through truss had become the standard structural type for long span bridges in Minnesota. Steel was first used in truss bridge design in the form of connecting eye bars, but by 1895 it had replaced wrought iron in nearly all structural members. Bridges from the 1890s represent the first extensive use of this material for bridge construction in Minnesota. It is the only remaining example of the George E. King Bridge Company's work in Minnesota.
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
bridge
Bridge
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
that spans the Straight River
Straight River (southern Minnesota)
The Straight River is a tributary of the Cannon River, 45 miles long, in southeastern Minnesota in the United States. Via the Cannon River, it is part of the watershed of the Mississippi River, draining an area of approximately 450 square miles in an agricultural region.Its name is a...
in Clinton Falls Township, Steele County, Minnesota. The public bridge was placed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
(NRHP) on January 25, 1997.
Structure
The Clinton Falls Bridge is a single spanSpan (architecture)
Span is the distance between two intermediate supports for a structure, e.g. a beam or a bridge.A span can be closed by a solid beam or of a rope...
, pin-connected steel Pratt through truss structure on concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
and limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
abutment
Abutment
An abutment is, generally, the point where two structures or objects meet. This word comes from the verb abut, which means adjoin or having common boundary. An abutment is an engineering term that describes a structure located at the ends of a bridge, where the bridge slab adjoins the approaching...
s. The overall dimension of the combined substructure
Substructure
In mathematical logic, an substructure or subalgebra is a structure whose domain is a subset of that of a bigger structure, and whose functions and relations are the traces of the functions and relations of the bigger structure...
and superstructure
Superstructure
A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships...
is 125 feet (38.1 m) by 22 feet (6.7 m).
The superstructure is eight panels and includes a floor system made up of 3 inches (7.6 cm) by 12 inches (30.5 cm) treated timbers on 5 inches (12.7 cm) steel I-section stringer
Longeron
In aircraft construction, a longeron or stringer or stiffener is a thin strip of wood, metal or carbon fiber, to which the skin of the aircraft is fastened. In the fuselage, longerons are attached to formers and run the longitudinal direction of the aircraft...
s which are themselves supported by 12 inches (30.5 cm) steel I-section floor beams
I-beam
-beams, also known as H-beams, W-beams , rolled steel joist , or double-T are beams with an - or H-shaped cross-section. The horizontal elements of the "" are flanges, while the vertical element is the web...
. These beams are fastened to the hip verticals with rivet
Rivet
A rivet is a permanent mechanical fastener. Before being installed a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole, and the tail is upset, or bucked A rivet...
ed plates and are riveted directly to the intermediate posts, except for one exception: the first post to the east on the south side is welded to the floor beam with a steel plate set eight inches off center; it is uncertain whether this was a repair or a correction of the design as it was being built. Both top and bottom lateral bracing consists of eye rods stabilized at intersecting points with bolted plates. The top chords, end posts, and intermediate posts are channels with riveted cover plates and lacing bars. The hip verticals are double forged eye rods, while the diagonals are double punched eye bars. The counters are turnbuckle
Turnbuckle
A turnbuckle, stretching screw or bottlescrew is a device for adjusting the tension or length of ropes, cables, tie rods, and other tensioning systems. It normally consists of two threaded eyelets, one screwed into each end of a small metal frame, one with a left-hand thread and the other with a...
s. The lateral and portal struts are double angles to which portal bracing (double angles) is connected with ledger plates. The portal struts and bracing make up a riveted unit which is bolted to the end posts. 2 inches (5.1 cm) by 6 inches (15.2 cm) wooden guard rail
Guard rail
Guard rail or guardrail, sometimes referred to as guide rail or railing, is a system designed to keep people or vehicles from straying into dangerous or off-limits areas...
s are boted to the bridge with angle sections. A builder's plate is fastened to the top portal struts at each end of the bridge.
The concrete, poured onto the limestone abutments and wing wall
Wing wall
A wing wall is a smaller wall attached or next to a larger wall or structure.-Bridges:In a bridge, the wing walls are adjacent to the abutments and act as retaining walls.They are generally constructed of the same material as those of abutments...
s, was added in 1975; other than that, the bridge is essentially in original condition. A fragmentary abutment, which supported an earlier, shorter structure at the same crossing, is located west of the current east bank abutment.
History
Settlement in the area of Clinton Falls Township began in the 1850s; by 1855, Steele County was created and the township officially designated. Clinton Falls was one of the county's first settlements, flourishing in large part because of the establishment of the first gristmillGristmill
The terms gristmill or grist mill can refer either to a building in which grain is ground into flour, or to the grinding mechanism itself.- Early history :...
in the county. That mill and its associated dam were listed together on the NHRP from 1986 until they were removed in 2004.
The current bridge is the second bridge built on the site. In 1867, the people of Steele County voted to build a covered bridge
Covered bridge
A covered bridge is a bridge with enclosed sides and a roof, often accommodating only a single lane of traffic. Most covered bridges are wooden; some newer ones are concrete or metal with glass sides...
for approximately $3000. It is believed that some of the abutments for that original bridge were used in the present one. In May 19, 1894, the Clinton Falls Township Board voted to build an "iron bridge" with steel joist
Joist
A joist, in architecture and engineering, is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a ceiling, roof, or floor. It may be made of wood, steel, or concrete. Typically, a beam is bigger than, and is thus distinguished from, a joist...
s over the river and awarded a contract to the George E. King Bridge Company of Des Moines, Iowa
Des Moines, Iowa
Des Moines is the capital and the most populous city in the US state of Iowa. It is also the county seat of Polk County. A small portion of the city extends into Warren County. It was incorporated on September 22, 1851, as Fort Des Moines which was shortened to "Des Moines" in 1857...
. The existing covered bridge was demolished in late September 1894. The old bridge was removed by September 27 and a large force began rapidly installing the new structure in its place. The new bridge was finished on October 2, 1894 and was described as "all iron and steel, except the planks and railing." On December 3, 1894 the Steele County Board agree to assume 60% of the cost of the bridge. The bridge was considered as an option for planners of the Jefferson Highway
Jefferson Highway
The Jefferson Highway was an automobile highway stretching through the central United States from New Orleans, Louisiana, to Winnipeg, Manitoba, Canada. The Jefferson Highway was replaced with the new numbered US Highway system in the late 1920s...
.
Over the decades, Clinton Falls Township faded away: the town's mill, school, church, store and post office all closed and the bridge became one of the few historic structures left. In 1970, the bridge was declared unsafe for vehicles and in need of repairs estimated at $3000. With few residents living on one side, the Township Board elected to close the bridge to all traffic. The plan was met with vehement opposition from residents on the isolated side of the bridge. The situation was resolved when Reuben Kaplan, the owner of a business in nearby Owatonna, Minnesota
Owatonna, Minnesota
Owatonna is a city in Steele County, Minnesota, United States. The population was 25,599 at the 2010 census. It is the county seat of Steele County. Owatonna is home to the Steele County Fairgrounds, which hosts the Steele County Free Fair in August....
, donated the money to repair the abutments and cement work and put in new wood planks and railings.
It carried Township Road No. 95 before it was closed to traffic again in 1994, its 100th year. Minnesota Department of Transportation
Minnesota Department of Transportation
The Minnesota Department of Transportation oversees transportation by land, water, and air in the U.S. state of Minnesota. The cabinet-level agency is responsible for maintaining the state's trunk highway system The Minnesota Department of Transportation (Mn/DOT, pronounced "min-dot") oversees...
made the decision after inspectors discovered that some of the steel stringers supporting the bridge deck had become dangerously thin from rust
Rust
Rust is a general term for a series of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture...
. Inspectors estimated repairs would total $105,981 to bring the bridge up to a five-ton standard weight limit. Local residents formed the Save the Clinton Falls Bridge Committee to raise money to repair the bridge as well as push for historic preservation. Concerned residents contacted the Minnesota Historical Society
Minnesota Historical Society
The Minnesota Historical Society is a private, non-profit educational and cultural institution dedicated to preserving the history of the U.S. state of Minnesota. It was founded by the territorial legislature in 1849, almost a decade before statehood. The Society is named in the Minnesota...
, which vetted their claims and hired a historian to prepare its NRHP nomination, which was successful. As of October 2010, the bridge remains closed to traffic.
Significance
The Clinton Falls Bridge is significant as an example of early steel truss bridge design in Minnesota. Highway bridges were an important part of European-American settlement in Minnesota. Wood and combination wood-iron bridges in various truss configurations were an important method of building medium and long spans, while masonryMasonry
Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone; concrete block, glass block, stucco, and...
arch construction was preferred for short spans. Initially, wrought iron
Wrought iron
thumb|The [[Eiffel tower]] is constructed from [[puddle iron]], a form of wrought ironWrought iron is an iron alloy with a very low carbon...
and wood were used in combination on Howe truss configurations. These bridges peaked in popularity in the 1870s. All-iron construction started to appear with bowstring arch bridges, but by the 1880s the pin-connected Pratt through truss had become the standard structural type for long span bridges in Minnesota. Steel was first used in truss bridge design in the form of connecting eye bars, but by 1895 it had replaced wrought iron in nearly all structural members. Bridges from the 1890s represent the first extensive use of this material for bridge construction in Minnesota. It is the only remaining example of the George E. King Bridge Company's work in Minnesota.