{"nrhp_refnum":"96001107","name":"State Highway 3-A Bridge at Plum Creek","other_names":["US90--US 183 Bridge at Plum Cr. (eastbound lanes)","Cw0029-03-"],"category":"structure","location":{"address":"US 90--US 183, .5 mi. W of jct. with I-10","address_restricted":false,"city":"Luling","county":"Caldwell County","state":"TX","lat":29.655525657000055,"lon":-97.60100408299996,"geom_source":"nps_gis"},"listed_date":"1996-10-10","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A steel Parker through truss highway bridge with 38 concrete deck girder approach spans, carrying the eastbound lanes of US 90/US 183 over Plum Creek about three miles southeast of Luling, Caldwell County, Texas. It was built in 1930-1931 and is about 1,205 feet long.","why_significant":"The bridge embodies the defining characteristics of a Texas Highway Department truss bridge, meeting Criterion C in Engineering at a state level. It is the only surviving example of the first version of the THD T22-120 standard design, which used horizontal bracing to prevent buckling of tall vertical members. Its integrity is retained despite a 1952 railing shortening and a 1990 deck upgrade.","narrative":"Spanning Plum Creek southeast of Luling, this steel Parker through truss bridge and its 38 concrete girder approach spans stretch about 1,205 feet and still carry eastbound traffic on US 90/US 183. Built between 1930 and 1931 by contractor Grant Williams for the Texas Highway Department, it used a standard truss design fabricated by the Virginia Bridge and Iron Company. The design, known as T22-120, relied on horizontal bracing across the central panels to prevent buckling of tall vertical members. This bridge is the only surviving example of that first version; later versions eliminated the bracing. It was listed for its engineering significance as a representative of a short-lived solution to a design problem. Changes include shortened approach railing in 1952, a companion westbound bridge in 1956, and new deck stringers in 1990. These alterations were judged minor, leaving the original structure and appearance largely intact.","period_of_significance":"1930-1931","architect_builder":"Bridge Designer: Texas Highway Department; Truss Fabricator: Virginia Bridge & Iron Company of Roanoke, Virginia; Bridge Builder: Grant Williams of Oklahoma City, Oklahoma","architectural_style":"Other: Parker through truss bridge","criteria":["C"],"status_note":"Still in use carrying two eastbound lanes of US 90/US 183; a companion bridge for westbound traffic was added in 1956.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:54:24.014883-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/7/9685/40968507/content/electronic-records/rg-079/NPS_TX/96001107.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/96001107/8196fd1c67-800.webp","url_1600":"https://nationalhistoricalregister.com/media/96001107/8196fd1c67-1600.webp","licence":"CC BY 4.0","author":"Larry D. Moore","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:State_highway_3a_bridge_plum_creek_2013.jpg\" rel=\"noopener\">Larry D. Moore</a>, <a href=\"https://creativecommons.org/licenses/by/4.0\" rel=\"license noopener\">CC BY 4.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:State_highway_3a_bridge_plum_creek_2013.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/40968507","wikipedia":null,"wikidata":"https://www.wikidata.org/wiki/Q110000929"},"indexable":true,"url":"https://nationalhistoricalregister.com/texas/caldwell-county/state-highway-3-a-bridge-at-plum-creek-96001107/"}