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| Key Facts |
| Bridge Name | Facility Carried / Feature Intersected | Location | Structure Type | Construction Date and Builder/Engineer | |
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Old Mill Road Bridge
| Old Mill Road (TR-421) Over White Deer Hole Creek | Rural: Union County, Pennsylvania | Metal 6 Panel Pin-Connected Pratt Through Truss, Fixed | 1889 By Builder/Contractor: Unknown |
| Technical Facts |
| Rehabilitation Date | Main Span Length | Structure Length | Roadway Width | Main Spans | NBI Number |
| 1994 | 86 Feet (26.2 Meters) | 90 Feet (27.4 Meters) | 15.4 Feet (4.7 Meters) | 1 | 59720304210002 |
This six panel truss bridge is a very noteworthy bridge because it appears to be an unaltered and early example of a bridge with standardized details (ie traditionally composed). This type of standardization became common by the 1890s, when companies gave up on having a bunch of unique patented details on their bridges and instead went with the tried and true standard compositions that seemed to be working most effectively. Constructed in the late 1880s, this bridge is an early and unaltered example of such standardization. As such, the bridge stands out as particularly significant.
This bridge carries a dead end road that appears to serve only one house, however the bridge and road remains publically owned.
The bridge has vertical members measuring roughly 12 inches by 5 inches and end posts measuring 12 inches by 6 inches.
Information and Findings From Pennsylvania's Historic Bridge InventoryDiscussion of Bridge The 1 span, 93'-long, wrought iron, pin-connected Pratt thru truss bridge was built in 1889 according to BMS records, but the bridge plaques documenting the date and builder have been lost. The trusses are traditionally composed with the lower chords and diagonals being eye bars, the upper chords being built up box sections, and the verticals being channels with lacing. The bridge has lattice portals with lattice brackets, and pipe railings that appear to be original are attached to the interior faces of the trusses. The built up floorbeams have U-shaped hangers. The wood stringers and deck were replaced in kind in 1994. The bridge is supported on fieldstone abutments. The bridge is an early and notably complete example of its type/design in a region with more than 120 truss bridges from the 1880s to 1940s. It is an early example of the all standard details that came to characterize the pin-connected Pratt truss type/design by the mid 1890s. It is historically and technologically significant. Discussion of Surrounding Area The bridge carries one lane unimproved township road over a stream in a rural setting. The road dead ends west of the bridge. All of the immediate quadrants are woods or fields. Beyond the western quadrants is an early 19th century vernacular stone farmhouse. Beyond the eastern quadrants is modern commercial development on US 15. The setting does not appear to have historic district potential. Bridge Considered Historic By Survey: Yes |
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Westbound Crossing of the Bridge Full Motion Video |
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Eastbound Crossing of the Bridge Full Motion Video |
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