Seattle is racing to get Fourth Avenue in SoDo ready for a crush of new bus traffic as the SODO busway prepares for permanent closure to make way for Sound Transit’s West Seattle Link. Right now, the corridor’s skinny sidewalks and almost nonexistent bus amenities are no match for the wave of buses and riders the agencies plan to reroute. The first round of work is aimed at adding new signals, widening waiting areas and tightening up crossings before those buses hit the street.
Seattle’s 4th Ave S Safety Project will install four-way traffic signals at South Walker Street and South Forest Street, as well as bus and curb bulbs that expand sidewalk space, plus new street lighting and trees at those stops, according to the Seattle Department of Transportation. The bus bulbs are sized so buses can load riders in-line at the curb, shorten pedestrian crossings and keep people waiting for buses out of the vehicle travel lanes. The project also includes upgraded ADA curb ramps and signal technology that could support future transit signal priority.
Funding and timeline
Two Washington State Transportation Improvement Board awards total about $2.79 million for the two intersections, with $1,472,174 for 4th Avenue South and South Walker Street and $1,318,675 for 4th Avenue South and South Forest Street, according to the Washington State Transportation Improvement Board. Those listings show environmental documentation and permits targeted for completion by April 30, 2026, with construction windows in late summer and early fall 2026. The Transportation Improvement Board materials also spell out that design and construction funding will cover the curb and bus bulbs, marked crosswalks, drainage improvements and landscaping.
How much bus traffic is coming?
Fourth Avenue currently sees roughly a dozen buses an hour. That number is projected to jump to about 60 buses per hour once the SODO busway is closed and routes are shifted, according to reporting by The Urbanist. That kind of spike helps explain why the city is scrambling to carve out more boarding space and add controlled crossings along the corridor. Planners say the goal is to juggle freight traffic, high bus volumes and pedestrian safety without completely snarling the area.
Work already under way
SDOT added a northbound freight-and-bus lane on a northern stretch of 4th Avenue South in 2025, creating dedicated space for King County Metro routes that use the corridor, according to the Seattle Transit Blog. That interim step is meant to boost reliability while longer term design and mitigation work move ahead. City staff say local businesses and freight operators will stay in the loop as construction is phased in.
Who will do the rest?
SDOT will handle the immediate intersection upgrades, while Sound Transit is expected to take the lead on later corridor work tied to the West Seattle Link project. That future package includes bus stop and intersection improvements at South Royal Brougham Way, South Holgate Street, South Spokane Street and South Lander Street, as reported by The Urbanist. SDOT spokesperson Ethan Bergerson told The Urbanist that the new signals will be able to “prioritize buses and improve traffic management during events or traffic disruptions,” a feature the city says will matter both during construction and on big event days. How the two agencies coordinate will shape the schedule and determine whether extra mitigation, such as full transit signal priority or additional boarding shelters, is needed.
For now, the work on Fourth Avenue is an early effort to keep buses moving and people on foot safer as major light rail construction reshapes SoDo. Riders, truck drivers and nearby businesses should expect construction notices as design and permitting wrap up later this year. SDOT and Sound Transit say they will keep reaching out to affected stakeholders as the plans are finalized.
