{"nrhp_refnum":"88000813","name":"Webster Donora Bridge","other_names":[],"category":"structure","location":{"address":"A 143 over Monongahela River","address_restricted":false,"city":"Donora","county":"Washington County","state":"PA","lat":40.18415317900008,"lon":-79.85197994499998,"geom_source":"nps_gis"},"listed_date":"1988-06-22","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A multiple-span steel through-truss highway bridge crossing the Monongahela River between Donora and Rostraver in Washington and Westmoreland Counties, Pennsylvania. It was built jointly by the two counties and carries a total length of 1,531 feet.","why_significant":"The nomination describes the bridge as an unusual example of a multiple-span through truss bridge combining two different truss types. Its main span is an unusually long Pennsylvania Petit truss, supported with four Parker trusses, showing how the truss form could be adapted to varied site conditions. The nomination identifies engineering as the area of significance.","narrative":"Steel through-truss highway bridge spanning the Monongahela River between Donora and Rostraver, carrying traffic across the Washington and Westmoreland County line. The two counties built it jointly, and the bridge was completed in 1908 by the Sofias Construction Company. It comprises five truss spans and nine girder and slab spans, with a total length of 1,531 feet. The main span is a 515-foot Pennsylvania Petit truss, the unusually long form that is the bridge's distinctive feature. Four Parker trusses complete the through-truss section, three measuring 184 feet and one 207 feet. The trusses were assembled on site from prefabricated members, including loop-welded and die-forged eyebars and riveted channels, bolted and pin-connected into their configurations. They rest on stone masonry piers. Its significance lies in its engineering, specifically the way one structure combines two truss types to suit varied site conditions. Later alterations, recorded in 1938, 1949, 1961 and 1966, have affected the fabric.","period_of_significance":null,"architect_builder":"Sofias Construction Company (builder)","architectural_style":null,"criteria":[],"status_note":"The form records alterations in 1938, 1949, 1961 and 1966, and notes that the bridge was reconstructed.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:36.064931-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/88000813.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/88000813/94085a445e-800.webp","url_1600":"https://nationalhistoricalregister.com/media/88000813/94085a445e-1600.webp","licence":"Public domain","author":"PennDOT","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Webster-Donora_Bridge.jpg\" rel=\"noopener\">PennDOT</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Webster-Donora_Bridge.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71994055","wikipedia":"https://en.wikipedia.org/wiki/Donora%E2%80%93Webster_Bridge","wikidata":"https://www.wikidata.org/wiki/Q5296804"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/washington-county/webster-donora-bridge-88000813/"}