About the new bridge
The new South Park Bridge on 14th Avenue S/16th Avenue S opened to traffic at 6 a.m. Monday, June 30, 2014. With two piers capped by brick-surfaced control towers and a sweeping bascule design, the new bridge recreates the look of its predecessor and returns a familiar silhouette to the lowrise South Park skyline. The King County Department of Transportation managed the project.
The new bridge spans the Duwamish waterway, a short distance from where the old South Park Bridge once stood. The structure is a bascule, or drawbridge, with two moveable leaves forming the main span so the bridge can be opened for marine traffic below.
The main bridge piers in the river are concrete, supported by sunken concrete caisson foundations. Both approach spans are made of precast concrete I-beam girders that support the bridge deck. The bridge has four driving lanes, two bike lanes and two sidewalks.
The project also included:
- intersection realignment, roadway improvement and safety upgrades in the South Park business area
- a rain garden with natural water treatment
- historic and art elements built into the new structure
- streetlights and bridge lighting
- riverbank cleanup and plantings
- utility relocation, and demolition of the remaining portions of the old bridge
The rain garden
The rain garden area packs a lot of features into a small strip of right-of-way. The pocket park is located on the footprint of the former South Park Bridge and provides much-needed access for the community to reach the river. It naturally filters runoff from the south half of the bridge and surrounding streets, lessening demand on Seattle's stormwater collection system. It also preserves local history by featuring many salvaged parts from the old bridge and offers a view of some of the art elements incorporated into the project under the 1% for Art program. Finally, interpretive signs in the area offer information on the area's history, archeology, bridges, and other topics of interest.
The old bridge
The old South Park Bridge was open from 1931 to 2010 and was an iconic feature of this historic community. The bridge was closed to all traffic on June 30, 2010, due to severe deterioration and earthquake vulnerability. The community and county leaders turned out in huge numbers for the last crossing of the bridge and continued efforts to identify and seek funding for a replacement bridge.
The community of South Park was tireless in its efforts to make sure the bridge and the connections it provides were not forgotten. County Executive Dow Constantine was ultimately successful in building a coalition of agencies to fund construction of a new bridge. U.S. Senator Patty Murray and U.S. Representative Jim McDermott were also instrumental in the effort, supporting the county's application to the U.S. Department of Transportation for a federal stimulus grant.
Final cost: $175 million
Bridge fun facts
- 27,600 cubic yards of concrete—enough to fill 2,760 fully loaded concrete trucks.
- Just two 75 horsepower motors required to run under normal speeds and normal operation—just a little more power than it takes to run a Prius.
- Main pier on south side of the bridge was sunk 70 feet below the river bed and contains more than 16 million pounds of concrete. The north pier was sunk half as much again (110 feet) and contains more than 21 million pounds of concrete.
- The new decking on the draw span is made up of lightweight concrete that is 22 percent lighter than regular concrete.
- 750,000 feet of electrical wiring—the equivalent to 83 homes or enough to stretch from South Park to Yakima.
- Rain garden made up of a two-foot thick layer of specially mixed bio-retention soil that filters runoff from the bridge as water drains through the soil. A perforated pipe at the bottom of the garden collects the cleaner filtered water and sends it to the river.
- The old bridge carried approximately 20,000 vehicles a day with 14 percent truck traffic.
- 14th Avenue S red brick road was removed, with the historic bricks being reused or preserved in sidewalks, crosswalks and other areas of the new bridge.