S Lander Street Overpass

City of Seattle, WA

The S Lander Street Overpass provides a new separated crossing to replace one of the nation’s most dangerous at-grade railroad crossings. Shortly after notice to proceed, the VE study team that reviewed the previous TS&L design for constructability and design improvements that ultimately redefined the project and saved the project $11M. Perteet led the civil design, including watermain, traffic, drainage, and roadway design elements. Raising the grade of S Lander Street with fully developed properties on all sides required close coordination with adjacent properties to maintain access, not only for the final configuration but also during the two-year construction that would close the road to through traffic. Because of the liquefiable soils on the corridor, we worked closely with SPU to replace the watermain along Lander that would end up underneath the bridge and geofoam approaches with pipe that can withstand a seismic event, including HDPE and ERDIP (Earthquake Resistant Ductile Iron Pipe), providing a more resilient system. As part of the design of the jack and bore under the railroad, the jacking pits were placed far enough from the railroad to avoid having to suspend work when a train was present.


  • Transportation

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