Miscauno Island Bridge (Middle)

Located at Miscauno Island, this through truss bridge is the middle of three bridges which carry the former Wisconsin & Michigan Railway over the Menominee River. At this location, the Menominee River splits into three channels, with the western and middle channel carrying much of the flow. While William Holmes & Sons constructed a logging railroad known as the Miscauno & North Western Railway (M&NW) to reach Miscauno Island in 1894, it is unclear if there was a bridge between the main island and eastern island constructed at that time. When the M&NW was acquired by the W&M in 1904, the Quinnesec & Western Railway (Q&W) was charted to connect the existing W&M mainline in Michigan to the former M&NW tracks at Miscauno Island. Work on the connection was substantially completed by late December 1904. It is believed that the present structure was constructed in late 1904 or 1905. Currently, the bridge consists of a 162-foot, 5-panel, pin-connected Pratt through truss span, set onto concrete abutments. The truss span is somewhat unusual, as it features a light pin-connected design which had fallen out of favor for railroad use around the turn of the 20th Century.

The truss span follows a standard design for railroad truss bridges constructed during the late 19th Century, with light built-up members, a standard floor and pin-connected members. The top chord, bottom chord and endposts are all composed of built-up beams, with V-lacing on the bottom and solid plates on the top. The bottom chord is similarly composed, with V-lacing on both the top and bottom. The vertical members are composed of slender built-up beams, which are built using V-lacing on two sides. At the bottom of the vertical members, the built-up beam forms a channel, which contains a pinhole at the base. The diagonal members are all composed of slender steel bars with eyebars at either end. Crash bars are present at the outer panels of the bridge, and use a V-laced design. The floor utilizes a standard design, with two plate girder stringers and plate girder floorbeams at the panel points. The portal bracing consists of a quadruple-intersection lattice design, with diagonal heel bracing at the endposts. The sway bracing uses a lighter variation of this design, with a deep double intersection lattice design. Both the upper lateral bracing and the lower lateral bracing are composed of slender steel bars, typical for spans from this era. The abutments use a standard design, with wing walls extending diagonally from the bridge.

The truss span was fabricated by an unknown contractor, while an additional unknown contractor constructed the concrete abutments. Vertical members of the identical western bridge are stamped with an "Eastern" brand embossing, although it is unclear if this company was responsible for fabricating the bridge or just producing the rolled steel. The Eastern Steel Company purchased the idle steel mill and bridge works of the Pottsville Iron and Steel Company in Pottsville, Pennsylvania in 1902. A 1903 directory of iron and steel works in the United States lists the Eastern Steel Company having a separate bridge works, with an annual capacity of 7,500 tons. This firm went bankrupt in 1931, and the facilities were acquired by the Bethlehem Steel Company. The Pratt truss design was undoubtedly the most popular railroad truss bridge design during the second half of the 20th Century. This design provided a simple configuration and great strength while balancing economy. Pin-connected Pratt trusses were largely superseded by riveted Warren trusses around the turn of the 20th Century. It is possible that a pin-connected design was chosen for this location due to cost, or possibly due to the complex field riveting process required for riveted truss spans.

Miscauno Island was developed into a resort for wealthy Chicagoans to vacation when the W&M completed the line across the island. The island provided natural beauty and space for fishing. A luxurious inn was initially constructed by the railroad in 1905, and remained in operation until a fire in 1923. In 1925, the resort was rebuilt with the present building, which has remained in use since. After the railroad abandoned the line to Miscauno Island, the railroad grade and bridges were reused for a road. As part of the conversion to a road, steel cable railings were added to the bridge and a wooden deck installed. The bridges at Miscauno Island are some of the only structures from the W&M which remain intact today. Overall, the bridge appears to be in fair condition, with significant cracking noted to the abutments. Despite the apparent deterioration to the abutments, the superstructure appears to be in good condition, with no significant deterioration noted to the steel. The author has ranked this bridge as being regionally significant, due to the truss design, age, railroad and reuse.