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| Name | CN Big Suamico River Bridge Chicago & North Western Railway Bridge #14 1/2 |
| Built By | Chicago & North Western Railway |
| Currently Owned By | Canadian National Railway |
| Superstructure Contractor | King Bridge Company of Cleveland, Ohio |
| Length | 120 Feet Total, 65 Foot Main Span |
| Width | 1 Track |
| Height Above Ground | 20 Feet (Estimated) |
| Superstructure Design | Deck Plate Girder and Timber Pile Trestle |
| Substructure Design | Timber Pile |
| Date Built | 1901 |
| Traffic Count | 5 Trains/Day (Estimated) |
| Current Status | In Use |
| Chicago & North Western Railway Bridge Number | 14 1/2 |
| Canadian National Railway Bridge Number | 14 1/2 |
| Significance | Local Significance |
| Documentation Date | 10/8/2022 |
In 1864, the Peninsula Railroad of Michigan (PRM) constructed 62 miles of new railroad, extending from Escanaba, Michigan to Negauee, Michigan. The PRM had originally been charted to connect the iron mines of the Upper Peninsula of Michigan to Lake Michigan at Escanaba. After completion of the line, the PRM would be purchased by William B. Ogden, and consolidated into the Chicago & North Western Railway (C&NW). This segment of line was originally disconnected with the rest of the C&NW system, which was beginning to expand in Wisconsin. A 5 mile extension to Ishpeming, Michigan was constructed in 1870 by the C&NW. In 1870, the C&NW constructed an additional 50 miles of railroad, extending from the end of the existing mainline at Green Bay, Wisconsin to Marinette, Wisconsin, on the Michigan border. The following year, a bridge would be constructed over the Menominee River, and an additional 64 miles of railroad constructed to Escanaba. This line soon became a major mainline for the C&NW, allowing the shipment of iron ore from the Upper Peninsula and allowing the construction of branch lines. North of Escanaba, numerous branch lines would be constructed to serve the mines of the area.
By the early 20th Century, the C&NW had constructed and acquired a large railroad network throughout the Midwest, making it one of the premiere railroads of the area. Throughout the first half of the 20th Century, this line remained critical for the C&NW, as it provided connections to a number of lines throughout northeast Wisconsin and the Upper Peninsula of Michigan. The line served a variety of industries, hosted passenger trains and was heavily used for hauling iron ore. The C&NW was acquired by Union Pacific Railroad (UP) in 1995. UP soon began to sell or abandon excess tracks acquired from the C&NW. The line from Green Bay to Ishpeming and the remaining mine branches were sold to a subsidiary of Wisconsin Central, Ltd. (WC). In 2001, WC was purchased by Canadian National Railway (CN), and became the American subsidiary of the railroad. Today, CN continues to operate the line between Green Bay and Gladstone, Michigan as the Marinette Subdivision, and the Gladstone to Ishpeming segment as the Ore Subdivision.
Located near the former station of Big Suamico, this deck plate girder bridge carries the former Chicago & North Western Railway mainline over the Big Suamico River. The first bridge at this location likely consisted of a timber pile trestle, constructed when the line was first built. It is believed that the original bridge was replaced in 1880 with a 56-foot wooden Howe deck truss span, approached by timber pile trestle spans on either end. Between 1896 and 1897, the bridge was reconstructed with a combination Howe deck truss span, and lengthened to cross a nearby street. Wooden and combination trusses were generally not suitable for most railroad traffic by the turn of the 20th Century, due to the perishable nature of the structures. In 1901, the bridge was rebuilt with a new deck plate girder span, installed on new timber pile piers. It is believed that the trestle connecting the river crossing and street crossing was mostly filled soon after the 1901 reconstruction, giving the bridge its present configuration. Currently, the bridge consists of a 65-foot deck plate girder span, set onto timber pile piers and approached by two timber pile trestle spans on either end. The main span uses a standard design, with two heavy plate girders and an open deck. Typical of timber bridges, the piers and approaches appear to have been renewed since the 1901 construction, possibly in the late 20th Century. King Bridge Company fabricated the main span, while railroad company forces installed all timber components. Deck plate girder spans were commonly used by railroads, as they were durable and easy to construct. It is somewhat unusual for a timber bridge to be located on this line, as it was a heavily used mainline for the C&NW. Often, railroads filled timber approach spans and constructed new stone or concrete substructures to carry an existing steel span. Since the initial construction, the bridge has seen no significant alterations, and remains in regular use. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The timber components also appear to be in fair condition, with no significant splitting immediately visible. The author has ranked the bridge as being locally significant, due to the common design.
Citations
| Builder and build date | King Bridge Company plaque |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |