S 277th Bridge No. 3126 Replacement Project
Construction scheduled to begin in spring 2021
This project replaces the 70-year-old S 277th Street Bridge No. 3126 over Mullen Slough with a four-sided concrete box culvert. The 16-foot-long bridge is located on a four-lane principal arterial road that connects Interstate 5 to State Route 167 in Kent and Federal Way.
Why King County is replacing this bridge
This existing S 277th Street Bridge is load-restricted and unable to support certain types of large trucks including some types of fire engines used by adjacent fire districts, full-size garbage trucks, dump trucks, and concrete mixers. The replacement culvert will provide unrestricted access for all vehicles. It will also provide environmental enhancements by improving fish passage and removing creosote timber pilings from Mullen Slough.
S 277th Street at this location has a traffic volume of about 23,000 vehicles per day, of which 2,600 vehicles are trucks carrying an estimated 4 to 10 million tons of freight per year. This road is a designated county snow/ice route, lifeline route, and Green River Valley flood evacuation route.
Construction will begin in spring 2021 and is expected to last approximately three months. Due to high average daily traffic on S 277th, and unfavorable detour routes, the existing bridge will remain open with travel lane reductions through the construction zone.
The estimated total project budget is $2.9 million. This project is funded through the King County Capital Improvement Program.
Notice of Action Taken (NAT) - Date of Action Taken, July 27, 2020 PDF 207KB
Environmental Checklist (ECL) - Issued, May 26, 2020 PDF 6MB (includes site plan and project plan sheets)
Determination of Non-Significance (DNS) - Issued, May 28, 2020 PDF 195KB
Esta pagina web - 28 de mayo de 2020 PDF 1MB
Determinación de no Impacto Adverso Significativo al Medio Ambiente (DNS por sus siglas en Inglés) - Fecha de emisión, 28 de mayo de 2020 PDF 198KB
Frequently asked questions
4 Axles - 24 T
5 Axles - 27 T
6 Axles - 31 T
7 Axles - 34 T
Either the north half or south half of the existing bridge will be demolished and replaced during Stage 1 construction while the traffic is shifted to the other half of the bridge.
Stage 2 of construction would move traffic to the newly constructed half of the new structure, demolish the remaining half of the existing bridge, and finish constructing the remaining half of the new structure.
S. 277th Street both directions (eastbound and westbound)
King County will place warning/advisory signs informing drivers of reduced lanes and reduced speed limit ahead.
King County will place signs notifying drivers of upcoming and current project construction and construction impacts.
Check King County's My Commute Map
All lane reductions will be listed in advance on the King County My Commute map.