|Bridge Name||Facility Carried / Feature Intersected||Location||Structure Type||Construction Date and Builder/Engineer|
||4th Avenue (PA-3039) Over Conemaugh River||Johnstown: Cambria County, Pennsylvania||Metal 14 Panel Rivet-Connected Baltimore Through Truss, Fixed and Approach Spans: Metal Stringer (Multi-Beam), Fixed||1914 By Builder/Contractor: Cambria Iron Works of Johnstown, Pennsylvania|
|Rehabilitation Date||Main Span Length||Structure Length||Roadway Width||Main Spans||Approach Spans||NBI Number|
|2001||269 Feet (82 Meters)||453 Feet (138.1 Meters)||22 Feet (6.7 Meters)||1||4||113039001007660|
This is one of the most unusual bridges ever to be seen. The truss structure run either level or slightly inclined, while the deck runs at a noticeable incline through the truss, meaning the deck is not parallel to the chords of the truss. This is not an alteration, and is how the bridge was originally designed. As a result of this bizarre design, there is some very unique details to the bridge. The most obvious is that the higher end of the bridge has less vertical clearance. The builders solved this problem by using a different design of portal bracing at this end, which is a single, solid box beam, which keeps the portal bracing to a minimum. At the lower end where clearance is not a concern, a more standard lattice design portal bracing is present. In addition, the support system for the deck as it runs through the truss varies from end to end. The floor beams rise along with the deck through the panels, but the bottom chord remains parallel. As a result, at the high end, an elaborate system of steel supports and braces connect the deck and floor beams to the bottom chord.
This bridge is, needless to say, among the most unusual of Johnstown's rich collection of historic bridges. It has a high level of historic significance for its unique engineering and design alone. However, it is significant for more reasons than just that. The bridge is significant as a local monument to Johnstown based Cambria Iron Works, a steel fabrication company that was prolific enough that many surviving truss bridges today across the country bear their name on their members. The Minersville Bridge was also apparently actually built by Cambria Iron Works, beyond just fabricating the steel for the bridge. As such, it is a noteworthy memorial to the company. In addition, the Minersville Bridge is noteworthy as a highway truss bridge displaying the uncommon Baltimore truss configuration. Finally, the bridge enjoys even more significance since it is a contributing part of the Cambria City Historic District.
Clearly, this is an important bridge. The routine maintenance and preservation of this beautiful, unique, and historic engineering achievement should come without thinking.
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