Project Location
Along SW 148th Street from 8th Avenue SW to 4th Avenue SW
Project Overview
This project includes widening northbound 4th Avenue SW to add a dedicated right-turn lane at SW 148th Street, replacing the existing traffic signal at 4th Avenue SW and constructing a new traffic signal at 6th Avenue SW. ADA-compliant accessibility improvements will also be made along SW 148th Street.
The purpose of the project is to improve both pedestrian and vehicular safety along the corridor.
Improvements will include:
- Dedicated right-turn lane on northbound 4th Avenue SW at SW 148th Street
- Dedicated left turn lanes at 6th Avenue SW
- ADA-accessible curb ramps
- Traffic signal replacement and new construction
- Drainage infrastructure
- Revised traffic channelization from Ambaum Boulevard SW to 6th Avenue SW
- SW to provide dedicated left turn lanes
See Site Map
Why is this project needed?
This project will improve safety and mobility for multiple users and functions. Localized vehicle traffic improvements are needed on 4th Ave SW as well as dedicated left turn lanes along SW 148th St for vehicular safety improvements.
Project Status
King County Signals (King County Road Services) is completing final inspection of the new signals at 4th Ave SW and 6th Ave SW.
Contractor is completing roadside and property restoration and final details with signal operations.
Substantial Completion: July 2026.
Project Manager
David Traub
Capital Projects Manager
[email protected]
Updated July 13, 2026