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| Key Facts |
| Bridge Name | Facility Carried / Feature Intersected | Location | Structure Type | Construction Date and Builder/Engineer | |
|---|---|---|---|---|---|
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CR-510 Bridge
| CR-510 Over Dead River | Rural: Marquette County, Michigan | Metal 12 Panel Pin-Connected Pennsylvania Through Truss, Fixed | By Builder/Contractor: Unknown |
| Technical Facts |
| Rehabilitation Date | Main Span Length | Structure Length | Roadway Width | Main Spans | NBI Number |
| 1921 | 265 Feet (80.7 Meters) | 271 Feet (82.6 Meters) | 19 Feet (5.8 Meters) | 1 | 52200031000B010 |
This is one of the largest, most beautiful, and most significant truss spans in Michigan. Not only does this truss bridge display the Pennsylvania truss configuration, it appears that it
may have actually come from the state of Pennsylvania. In 1919, the Michigan State Highway Department purchased the bridge which originally crossed the Allegheny River. Relocating and reusing truss bridges was not unusual in this period of
history. An example notice indicating bridges for sale from 1921 is shown to the right. At this time, CR-510 was a state trunk line route and purchasing and
relocating this bridge would have been an inexpensive alternative to building a new bridge from scratch. It was erected on the CR-510 location in 1921. The Michigan State Highway Department's Biennial Report stated that the bridge was one
of two toll bridges crossing the Allegheny River within 500 feet of each other and was being removed due to the redundancy. Unfortunately, the report did not state exactly where on the river this bridge came from. Since most of the
Allegheny River is in Pennsylvania, it is assumed the bridge came from Pennsylvania, although the Allegheny River does dip into New York State for a short time. Depending on where on the Allegheny River it was originally located, it may
have been part of a multi-span bridge.
Pennsylvania truss bridges are an uncommon truss type, and the nature of their design means that they are reserved for longer truss spans. However, even among pin-connected highway Pennsylvania truss spans, this bridge's span still stands out as fairly long. It is the longest pin-connected highway truss span in Michigan. The truss type is extremely rare in Michigan, and so the bridge has additional significance in the context of Michigan. The bridge also retains excellent historic integrity with minimal alterations despite its long service and being located in two different states over its service life. The bridge has decorative details on its portal bracing, another feature that is rare among Michigan truss bridges.
In 2010, this bridge was replaced by a new high level bridge on new alignment a short distance west of the historic bridge. Fortunately, Marquette County did not demolish the historic bridge. Instead, the bridge was left standing for its historic value and remains open to pedestrians. The county even did substantial work to create a walkway that approaches the bridge on a more even grade. No work was done on the historic bridge, however the bridge is not in severe condition. At the same time it is worth noting that the paint system is failing and rust and section loss have been developing in the typical trouble spots like the bottom chord. However, now that the bridge is away from vehicular traffic and corrosive deicing salts the rate of deterioration should greatly slow. A long term goal worth considering would be to plan for a project to repair and repaint the bridge. However, in the meantime, the bridge is safe from both demolition and deterioration from vehicular traffic.
It should be worth noting that other states like Pennsylvania have refused to leave historic bridges standing when they are replaced by a bridge on new alignment. One of the reasons cited is liability. Firstly, these concerns about liability are unfounded since no proof has ever existed that a substantial number of historic bridge related lawsuits have ever occurred. Furthermore, Marquette County has demonstrated how easy it is to reduce or eliminate liability. Signs are posted at the walkway leading to the bridge that read "MCRC Property Enter At Own Risk." While these signs do not prohibit people from visiting and enjoying the bridge, they also indicate that MCRC is not responsible for any injury occurring at the bridge site.
A photo of this bridge appeared in the 1922 Biennial Report of the Michigan State Highway Department. The photo is shown below.
Information and Findings From Michigan Historic Bridge InventoryNarrative Description This bridge is a rare Pennsylvania through truss highway bridge, particularly because of the length (271 ft.) of this single span. It was purchased by the State Highway Department in 1919, moved from an unspecified Allegheny River site, probably considerably upstream from Pittsburgh, an then erected on this site in 1921. |
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