Miscauno Island Bridge (East)

Located at Miscauno Island, this through truss bridge is the eastern 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. The Miscauno & North Western Railway (M&NW) first reached Miscauno Island in 1894 from the Wisconsin shore. This railroad was a logging railroad, owned by William Holmes & Sons. 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. A contact was awarded to Lorimer & Gallager for the rapid construction of the new line and the present bridge, which was substantially completed by late December 1904. Currently, the bridge consists of a 92-foot, 4-panel, riveted Warren pony truss span, set onto concrete abutments. The truss span appears to follow a standard design for the W&M, with a similar bridge having been constructed at Peshtigo, Wisconsin the following year.

While the truss design seems to have been standard for the W&M, the span itself is quite unusual for railroad standards. The trusses use an exceptionally light design, consisting of no laced built-up beams. The top chord, bottom chord, endposts and diagonal members are all composed of L-shaped bars, which are riveted together to form a beam with a single flange. The top chord and endposts are connected by a riveted plate, which is angled over both components. The vertical members are composed of thin plates, which have L-shaped bars on the edges. These plates use a unique curved design, and are riveted directly to the floorbeams. Although the truss itself is relatively lightweight, the floor is heavily constructed, consisting of two large plate girder stringers and plate girder floorbeams placed at the panel points. The bottom lateral bracing is also constructed of L-shaped bars. Furthering the unusual appearance of this bridge, the lower connections are significantly larger than the upper connections. The gusset plates for the upper connections are formed out of small steel plates, while the lower connections are formed with larger steel plates, riveted to the end of the floorbeams. The truss span was fabricated by an unknown contractor, while Lorimer & Gallager constructed the concrete abutments. This bridge was constructed at a time when railroads were transitioning from using pin-connected trusses to riveted trusses. During the first years of the 20th Century, riveted Warren trusses became the standard for railroad use. Many of these trusses were heavily constructed, using large laced beams and heavy floors. This span appears to be an outlier, with the trusses appearing closer in design to a highway bridge.

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 unique truss design, age, railroad and reuse.