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Dunbar Bridge

Harmon Creek Road Bridge

Dunbar Bridge

Primary Photographer(s): Nathan Holth

Bridge Documented: July 4, 2006 and May 3, 2013

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Key Facts

Facility Carried / Feature Intersected
Harmon Creek Road (TR-843) Over Raccoon Creek
Rural: Washington County, Pennsylvania: United States
Construction Date and Builder / Engineer
1889 By Builder/Contractor: Pittsburgh Bridge Company of Pittsburgh, Pennsylvania

Technical Facts

Rehabilitation Date
Not Available or Not Applicable
Main Span Length
60 Feet (18.3 Meters)
Structure Length
20 Feet (5.9 Meters)
Roadway Width
10.5 Feet (3.2 Meters)
1 Main Span(s)
NBI Number

Historic Significance Rating (HSR)
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Bridge Documentation

This bridge no longer exists!

View Archived National Bridge Inventory Report - Has Additional Details and Evaluation

You know that when even Pennsylvania's outdated and overly conservative Historic Bridge Inventory says a truss bridge is historic, that the bridge is something extra special! Indeed, that is the case with this very old 1889 half-hip Pratt pony truss with pinned connections. The bridge features latticed vertical members. There is v-lacing on both sides of the end posts, which is unusual since normally cover plate would be expected on top of the built-up box section. Original pole railings remain on this bridge. The other unusual feature is the use of rolled star iron, also called cruciform, on the outriggers. Star iron usually shows up on 1870s truss bridges, such as the bowstring truss bridges that were common during that period. If the 1889 construction date listed for this bridge is accurate, this would be a late example of a bridge with star iron on it. Regardless, any bridge that has star iron on it is rare and has historic significance. This bridge is, based on its style, assumed to have been built by the Pittsburgh Bridge Company.

Information and Findings From Pennsylvania's Historic Bridge Inventory

Discussion of Bridge

The single-span, 64'-long and 12' wide, pin-connected Pratt pony truss bridge built in 1889 is supported on one stone abutment and one concrete abutment. The lower chords and diagonals are loop forged eyebars, and the upper chords are channels and lacing. The verticals are laced back to back angles. Original features include the built up floor beams, pipe railings inside the truss lines and the outriggers. In a county and region with a deep and varied collection of metal truss bridges from the mid 1880s through the 1930s, this pony truss bridge stands out as an early and complete example.

Discussion of Surrounding Area

The bridge carries a single lane road over a stream in a sparsely developed, forested setting.

Bridge Considered Historic By Survey: Yes


Photo Galleries and Videos: Dunbar Bridge

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Maps and Links: Dunbar Bridge

This historic bridge has been demolished. This map is shown for reference purposes only.

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