Algona Railroad Crossing

Located in Algona, this quadrangular lattice through truss bridge carries a former Chicago & North Western Railway line over a former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) line. The first bridge at this location likely consisted of a timber pile trestle, with a short beam or girder span crossing the Milwaukee Road tracks. This bridge is not believed to have been replaced as part of the first improvement program for this line, which saw several timber bridges replaced with steel and stone structures between 1900 and 1905. In the late 1910s, the C&NW began a second major improvement program along this line, replacing several remaining timber bridges with steel and concrete structures. The present structure was constructed in 1917. Currently, the bridge consists of a 120-foot riveted quadrangular lattice through truss span, set onto concrete abutments. American Bridge Company fabricated the superstructure, while an unknown contractor constructed the concrete abutments.

The truss span is heavily constructed, using large built-up members, a standard floor and a utilitarian portal bracing. The endposts are comprised of heavy beams, which use a solid plate on the outside and heavy V-lacing on the inside. Solid plates are used to connect the channels where the portal bracing meets the endpost. The top chord is composed of two U-shaped channels, connected by a tight V-lacing on the bottom and a solid plate on the top. The bottom chord uses a similar design, with V-lacing on both sides and circular cutouts at the connection points to allow water to drain, an improvement over earlier designs. The compression members consist of solid beams, while the tension members consist of L-shaped steel bars. Unique to this span, the floor system is heavily constructed, using plate girder floorbeams and four stringers, which are set equidistant underneath the tracks. This shallow design was likely chosen to maximize clearance underneath. The lower lateral bracing is constructed of heavy L-shaped bars. The portal bracing consists of a standard A-frame design, constructed of heavy V-laced beams. The sway bracing and upper lateral bracing also are composed of V-laced beams. The diagonal members are constructed of a combination of rolled beams, solid plates and built-up beams comprised of heavily V-laced members. Typical for spans of this design, the portal bracing uses an A-frame design, comprised of built-up beams with heavy V-lacing. The top lateral bracing consist of V-laced plates, and the bottom lateral bracing consists of steel bars. The floor is traditionally composed, with plate girders forming the two stringers and floorbeams. The deck girder also uses a standard design, with shallow girders and an open deck. Typical of bridges along this line, the abutments are constructed of an elongated U-abutment, while the pier is a diamond shaped structure. Pennsylvania Steel Company fabricated the superstructure, while the Bates & Rogers Construction Company constructed the substructure. All substructures are founded on timber piles, typical of construction along this line.