Northbound HOV3Transit I-5 express lanes entrance at Mercer Street in Seattle opens May 12

The Washington State Department of Transportation will open a new entrance for northbound high occupancy vehicle (HOV3+) and transit I-5 express lanes at Mercer Street on May 12. This entrance will allow qualified vehicles to access express lanes from the left side of Mercer Street, using a ramp that had previously served only southbound traffic. The change is part of the SR 520/I-5 Express Lanes Connection Project, which includes building a new flyover ramp to connect express lanes to State Route 520. The new entrance is exclusively for HOV3+ and transit vehicles, and non-HOV3+ travelers will continue using existing access points. The project includes significant updates, such as ramp metering changes based on the direction of the express lanes.

Northbound travelers will use two-lane ramp meters when express lanes operate southbound, while a single-lane meter will be used for northbound operations. The full benefits of the new entrance will emerge after the completion of the SR 520 Portage Bay Bridge and Roanoke Lid Project in 2031, which will allow for reversible traffic flow. This initiative aims to enhance traffic efficiency and support regional transit goals.