NS Mackinaw River Bridge

View an article describing the erection method used for this bridge

Located between Goodfield and Congerville, this large Warren deck truss bridge carries the former Nickel Plate Road over the Mackinaw River. Historically, this location had been known as Mackinaw Dells. The first bridge at this location likely consisted of a timber truss bridge, supported by timber pile piers. In 1895, the bridge was reconstructed with a new steel bridge, set onto new stone substructures. This bridge consisted of three 160-foot pin-connected Pratt deck truss spans, approached by a deck plate girder span on either end. It is believed that this bridge may have been constructed by King Bridge Company, which constructed a number of other bridges for the Lake Erie & Western between 1895 and 1896. It is unknown which contractor constructed the stone substructures. As traffic increased and became heavier in the 20th Century, the bridge would be strengthened in 1934. By the mid-20th Century, a number of 1890s bridges along this route had become too light for traffic. As a result, the Nickel Plate undertook a project to upgrade steel bridges with modern structures.

The replacement of the Mackinaw River bridge was one of the first projects completed along this line. To minimize disruptions to traffic, it was decided to reconstruct the bridge by reusing the old stone substructures. First, temporary timber bents were constructed both downstream and upstream of the bridge. These timber bents were equipped with specialized rollers, which would allow the bridges to be slid with minimal effort. The steel spans were assembled on a temporary spur track, located approximately 900 feet west of the bridge. After the spans were assembled, they were moved one at a time to the downstream bents using two heavy cranes. A system of cables was attached to the old and new bridges to facilitate the swap of the spans. On the day of installation, the old bridge was moved to the upstream bents and the new bridge shifted to the final position in only 19 minutes. After the new bridge was complete, the old steel spans were disassembled and likely scrapped. Nickel Plate Road Bridge Engineer Reginald T. Blewitt designed the new structure, and an unknown contractor fabricated the new spans. Ferro Construction Company oversaw the erection and devised the method of swapping the spans. The erection method resulted in virtually no delay to traffic over the bridge.

Currently, the bridge consists of three 160-foot, 6-panel riveted Warren deck truss spans, approached by a 54-foot deck plate girder span on the west end and a 60-foot deck plate girder span on the east end. All spans of the bridge, with the exception of the 60-foot span, use an open deck. The 60-foot span uses a concrete ballast deck, a typical design for the Nickel Plate. The trusses use a combination of solid and built-up members, and the floor consists of a traditional design of stringers and floor beams. Due to the newer age of the bridge, all spans use less rivets than spans constructed earlier in the 20th Century. At the time of construction, a number of repairs were made to the bridge, including the encasement of the west abutment, east abutment and pier #2 with concrete. It is believed these repairs were made by railroad company forces. While truss bridges had largely fallen out of favor by the mid-20th Century, it is believed that the railroad decided to construct a new truss bridge to minimize interruptions to traffic. Warren trusses became the standard truss bridge design for railroads in the 20th Century, as they were strong, simple and easy to construct. Since the initial construction, the bridge has seen little if any changes. Overall, the bridge appears to be in good condition, with very little deterioration noted on the structure. The author has ranked this bridge as being moderately significant, due to the truss design and newer age.