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| Key Facts |
| Bridge Name | Facility Carried / Feature Intersected | Location | Structure Type | Construction Date and Builder/Engineer | |
|---|---|---|---|---|---|
| S |
6th Street Bridge
| Sixth Street Over Railroad (Norfolk Southern) | Griffin: Spalding County, Georgia | Metal 6 Panel Pin-Connected Warren Through Truss, Fixed and Approach Spans: Metal Stringer (Multi-Beam), Fixed | By Builder/Contractor: Unknown |
| Technical Facts |
| Rehabilitation Date | Main Span Length | Structure Length | Roadway Width | Main Spans | Approach Spans | NBI Number |
| 1912 | 100 Feet (30.5 Meters) | 695 Feet (211.8 Meters) | 27.2 Feet (8.3 Meters) | 1 | 5 | 25500480 |
Georgia has very few metal truss bridges, and as such, a bridge like this one, which would stand out in the most truss-rich state in the country, is so rare and significant that it might be the most important historic bridge in the entire state. The central reason for its rarity is the truss configuration of this bridge, that of a pin-connected Warren truss bridge, it a form that is extremely rare. Nearly all surviving Warren truss bridges have riveted connections. The bridge is also significant as an earlier pin-connected railroad truss bridge. Most pin-connected truss bridges from the 1880s or earlier were destroyed by the early 20th Century due to increases in weight of trains. This bridge appears to date to ca 1888 and was originally built at an unknown location to serve trains. It most likely was a "normally" configured two-span bridge since the single span, double truss configuration as seen on the road today would not have been needed for a train. It was relocated and erected in its current site in 1912. In 1958, wooden stringer approach spans were replaced with the steel stringers present today. Portions of the bottom chord and connections were encased in concrete and asphalt an alteration that has recently been partially removed at the connection points.
The bridge is unusual because it is two independent truss spans sitting side by side on a shared substructure to form a single two lane bridge. This is different from some wide truss bridges that have three truss lines, with one line in the center. The center of this bridge has two independent truss lines yielding a total of four truss lines.
The bridge also displays distinctive/unusual design details. The orientation of the sway bracing is such that the v-lacing is on the top and bottom of the built up beams. Usually with sway bracing of this design, the v-lacing/lattice is on the sides of the beam. The first section of bottom chord extends from the end post across two panels before it is connected to a vertical member. In other words, it is not connected to the hip vertical which is unusual. The pedimented portal bracing and the design of its associated knee bracing is both uncommon and beautiful.
The pin-connected Warren truss bridge is a good teaching bridge because pin-connected truss bridges typically display eyebars for tension members and built-up beams for compression members, which allows viewers to see which members in a Warren truss contain tension and which contain compression. Warren truss diagonal members alternate between tension and compression, although the two central diagonals are often in compression or they experience minimal forces.
There are plans to replace this bridge, but the historic truss spans are to be carefully marked, disassembled and stored for future restoration and re-erection.
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