This is a beautiful two span Pratt through truss bridge, and one of the most significant examples of the Joliet Bridge and Iron Company's work in Michigan. It retains plaques at both ends of the bridge, and also original channel guardrails. Also, due to the fact that it is two-span, it is very rare for Michigan which has an unusually small number of surviving multi-span truss bridges. It is also simply a beautiful bridge, more beautiful than any modern bridge could hope to be with its lightweight yet intricate truss and built-up beam geometry. It is located in a scenic area with a companion historic railroad truss bridge nearby. It is one of the very few places in the entire state of Michigan where more than two or more truss bridges can be seen together. An interesting fun fact is that two different companies fabricated the channels composing the built-up end posts: some channels have Cambria markings, while others have Carnegie markings. It is common to have multiple fabricators for the different types of beams on truss bridges, but it is less common to find multiple fabricators for identical parts/beams.
Prior to restoration, the traditionally composed truss was configured as follows: Connections: pinned with recessed nuts. Top chord and end post: back-to-back channels with v-lacing and cover plate. Bottom chord: up-set eyebars. Vertical members: back-to-back channels with v-lacing on each side. Hip vertical member: loop-forged eyebars. Diagonal members: up-set eyebars. Sway bracing: paired angles with v-lacing between and no knee bracing. Portal bracing: single row of large-size lattice composed of riveted angles, and a knee brace formed from a single angle. Deck: metal deck stringers wooden deck and asphalt wearing surface. Railing: two rows of channel. Floor beams: rolled American Standard i-beams. Lateral bracing: threaded rod with nuts. Identified metal fabricators: Cambria and Carnegie. There also was a partial mark observed on a deck stringer that appeared to be Jones and Laughlin. Following restoration, this configuration remained the same except for the replacement of the deck and deck stringers.
The State Street Bridge, one of Michigan's few remaining multi-span metal truss bridges, has been restored for pedestrian use in its original location, representing a major step forward for historic bridge preservation in Michigan. In January 2010, the restoration project for this historic bridge began at a total approximate cost of $2.15 Million. The bridge spans were moved to a temporary restoration work site where they were dismantled, shipped to Bach Ornamental and Structural Steel to be restored for placement back over the bridge.
Prior to restoration, there was still some lingering paint on this bridge, although rust had taken a toll on the integrity of some of the bridge including sway bracing at the connection points. One unusual area of heavy deterioration was the top chord cover plate which had significant section loss. However the main need for a restoration project was the substructure of the bridge. The south/west end of this bridge sat on a concrete pier that was rotating, essentially slowly tipping over. For years the south/west truss span had a twisted appearance since the truss had rotated along with the pier. In the final years and even months leading up to restoration, pier rotation had accelerated, and the bridge had become at risk for collapse. The bridge also exhibited considerable deterioration including pack rust and section loss in the cover plate and in the areas in and around the bottom chord connections, a typical trouble spot for old truss bridges.
Since 2004, HistoricBridges.org had a page for this bridge commenting on the rotating pier problem and suggesting that restoration for pedestrian use would save the bridge from tipping over, and would be of great benefit, connecting a park area south of the bridge to residential areas north of the bridge, and also reduce the dangerous use of the railroad bridge by locals in these residential areas trying to access the park.
Despite the problems with the bridge, this bridge was still in a restorable condition, and thanks to a number of people committed to ensuring this bridge has a future, a comprehensive restoration project was secured for the historic truss superstructure which resulted in this bridge being reopened in its original location for non-motorized traffic. The restoration replaced the deficient and failed substructure, and executed an in-kind restoration on the truss. In-kind restoration is the preferred type of preservation that ensures that as much original material on the bridge as possible will be preserved, and anything that must be replaced will be exactly replicated and the design and function of the truss must not be altered. Rivets will be replaced with rivets, v-laced beams will be replaced with v-laced beams and not wide-flange beams, etc. There will be no ugly retrofits or welded plates covering the bridge.
The existing approach spans of the bridge were reused. The substructure for the main spans were completely reconstructed due to their failed and/or deficient condition. Note that the simple concrete substructure was never part of the bridge's historic significance. The new substructure also raised the truss bridge spans up by one foot which provide the bridge greater protection from flood damage. This was a critical step to prevent a catastrophic disaster like what happened in Chesaning. The bridge was repainted in a black color, which for unknown reasons is a popular color for restored truss bridges in Michigan. The original channel railings were placed back on the bridge for the sake of historic integrity, with modern railings being place on the deck in front of those for the sake of safety and code requirements.
Those involved with the restoration of this bridge hope that not only will the bridge improve the quality of life in Bridgeport, but that it will become an example project that will inspire high quality historic bridge preservation elsewhere. HistoricBridges.org thanks Bridgeport Township for initiating this preservation project and MDOT for providing funding assistance. Spicer Group was the engineer for the project, and Davis Construction was the contractor. Bach Ornamental and Structural Steel was the fabricator in charge of restoring the individual bridge parts. Vern Mesler was retained by Spicer Group to assist in developing the in-kind restoration procedures.
Information and Findings From Michigan Historic Bridge Inventory
State Street Bridge is one of only six surviving late 19th century and
early 20th century multi-span through truss highway bridges left in
Michigan. It is also one of two key surviving examples of bridges in
Michigan produced by the Joliet Bridge and Iron Company of Joliet,
Illinois, one of the leading producers of Michigan's metal truss highway
bridges in the early twentieth century.
This bridge is tagged with the following special condition(s): Unorganized Photos and Reused
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