Statement of Significance: Summary
Constructed over the Duwamish River in 1931, the South Park Bridge was listed on the NRHP on 06/16/1982 and designated as a King County Landmark in November 1996. The bridge is listed on the NRHP under Criterion A for its association with the land reclamation and industrialization efforts in the Duwamish River valley, the urbanization of South Park and other communities along the River, and the development of the Seattle road system and waterways during the first half of the 20th century. Designed by the Scherzer Rolling Bridge Company of Chicago and constructed by the Puget Sound Bridge and Dredging Company, the bridge provided a vital link between the industrial facilities in South Park and other South King County communities with the Boeing facilities and other Seattle industries (Soderberg 1980; Palmer and Palmer 1996; HRA 2004). The bridge is also listed on the NRHP under Criterion C for its engineering/construction significance and distinctive bridge style. It is a distinctive example of the early 20th century moveable bascule bridge that replaced swing bridges during this period. The speed of operation and greater clear opening that resulted from its ability to retract led to the bridge type’s popularity in urban settings and congested waterways like the Duwamish. The structure is the only extant Scherzer Rolling Lift Bascule Bridge in Washington State.
Statement of Significance: Early South Park Bridge
The first South Park Bridge was a wooden drawbridge constructed during 1914–1916, approximately 100 feet north and downstream of the current South Park Bridge. 14th Avenue S, a historic brick roadway, was the western approach to the early South Park Bridge. The draw bridge and brick road connected the growing urban centers of South King County and South Park with the Duwamish River delta communities and the growing metropolis of Seattle. This bridge proved inefficient, however, because the center pivot pillar allowed logs to collect on the pilings and block passage (Palmer and Palmer 1996). It was replaced by the current South Park Bridge in 1931, a Scherzer rolling lift bascule type. The wooden drawbridge was demolished soon thereafter (Palmer and Palmer 1996).
Statement of Significance: Current South Park Bridge
The current South Park Bridge is the only Scherzer rolling lift bascule bridge extant in the State of Washington. The Scherzer Rolling Lift Bridge Company of Chicago designed the bridge, the Wallace Bridge and Structural Steel Company fabricated the steel for the structure (Soderberg 1980), and the Puget Sound Bridge and Dredging Company constructed the current bridge under the supervision of the King County Engineering Department. The Chicago firm participated in numerous industrial construction projects that changed the face of Seattle and Elliot Bay. The company built many of the area’s most important engineering landmarks, including Harbor Island, the Lake Washington floating bridge (SR 520), and the Dexter Horton Building in downtown Seattle (Palmer and Palmer 1996). Construction of the current South Park Bridge was the result of one of the most concentrated bridge building efforts in Seattle’s history. Development of the lower Duwamish River delta into an industrial and harbor area promoted construction of four moveable bascule bridges over the Duwamish, including the South Park Bridge. Increased industrialization and urbanization in other parts of the city led to the construction of bridges over the Lake Washington Ship Canal and the floating bridges over Lake Washington (Holstine 2002). The bascule design was widely adopted during this period of concentrated bridge development in Washington State. Developed by engineer William Scherzer of Chicago, the bascule bridge’s advantages included a wide center channel free of piers, increased spacing for docking, and fast operating speed. These attributes were particularly suited for locations such as Seattle and Chicago, where heavy bridge traffic must be frequently interrupted by boat service (Palmer and Palmer 1996). Construction of the South Park Bridge followed the development of four doubleleaf trunnion bascule spans over the Lake Washington Ship Canal by Seattle city engineers (between 1915 and 1925) as well as two earlier bridges over the Duwamish River at Spokane Street. Seattle made engineering history with the 1955 construction of the 1st Avenue S Bridge over the Duwamish that supported a double-leaf bascule bridge on floating piers (Holstine 2002). The current South Park Bridge has a 125-foot opening that allows ocean-going ships to continue south along the Duwamish to upstream industrial sites. The bridge was constructed approximately 100 feet upstream from the earlier South Park Bridge, which slightly shifted the bridge approach from 14th Avenue S to 16th Avenue S. Historically, the bridge served as one of the roadway links that aided in the expansion of Boeing Field and industrialization efforts along the Duwamish. The bridge also facilitated commercial development of South Park and the Duwamish River delta communities (Palmer and Palmer 1996). Channeling and straightening of the Duwamish River during the second decade of the 20th century and subsequent land reclamation projects allowed for several bridges to be constructed over the Duwamish, including the first (demolished) and the second (current) South Park Bridge. The bridge linked 14th and 16th Avenue S to Highway 99 and other major highways and railroads in the region.
Statement of Significance: Physical Description
The South Park (14th Avenue S/16th Avenue S) Bridge is a Scherzer rolling lift bascule bridge constructed of steel rebar-reinforced poured concrete. The four-lane asphalt-surfaced bridge spans the Duwamish River in an east-west alignment, composed of two 95-foot leaves, 26 concrete slab approach spans, and a 38-foot-wide roadway (curb to curb). Including the approaches and pedestrian walkways, the bridge measures 1,285 feet long (Soderberg 1980). Beneath the terrestrial piers, vertical clearance is 16 feet 8 inches; and vertical clearance from the Duwamish River at mean high tide is 32 feet. The opened bridge provides a water channel that is 125 feet wide (Palmer and Palmer 1996). Abutments, piers, and pylons are constructed from steel girders (I-beams) and trusses. The two concrete abutments (one on each side) supporting the center span have one-over-one windows on the east and west sides, of which some have been replaced, some are missing, and some have been boarded up. Atop each center span abutment stand one-story single-room brick bridge tender structures with red-tiled hip roofs and threeover- one transom windows on all sides. The west side of the northernmost structure contains a plaque marking its name, construction date, and administrative personnel related to its construction. Original concrete light posts (without fixtures) are situated along the concrete balustrades and are alternated by replacement concrete light posts. Pedestrian walkways along the center span are steel grids filled in with the concrete. A steel balustrade is installed along the pedestrian walkway in the center span. A concrete balustrade, embellished with concrete piers approximately every 20 feet, adorns the approaches to the bridge. Each end of the center span holds a pair of traffic crossing arms (Palmer and Palmer 1996).
Major Bibliographic References
Holstein, Craig and Richard Hobbs
2002 Spanning Washington Historic Highway Bridges of the Evergreen State. Washington State University Press, Pullman, Washington.
Palmer, Kevin A. and Palmer, Christine S.
1996 14th Avenue South Bridge. King County Landmark Registration Form. On file, King County Office of Business Relations and Economic Development, Seattle, Washington.
1980. Historic Bridges and Tunnels in Washington State. National Register of Historic Places Inventory: Nomination Form. On file, Washington State Office of Archaeology and Historic Preservation, Olympia, Washington.