Crews will open the new northbound high occupancy vehicle three-plus passengers (HOV3+) and transit Interstate 5 express lanes entrance at Mercer Street on Monday, May 12, the Washington State Department of Transportation said. The new entrance will follow the same schedule as the I-5 Express Lanes.

Northbound HOV3+ and transit will soon enter the express lanes from the left side of Mercer Street– using the same ramp that had exclusively been used for southbound express lanes traffic.

The Washington State Department of Transportation recently posted an update video on YouTube showing the new entrance and how it will work.

The express lanes off-ramp to Mercer Street was previously used in the morning for southbound traffic. In 2024, crews added a concrete median barrier to separate the southbound off-ramps, allowing the express lanes off-ramp to serve as a reversible ramp.

The new entrance into the northbound express lanes is part of the SR 520/I-5 Express Lanes Connection Project. This project built a new flyover ramp over NB I-5, connecting the express lanes to State Route 520 in addition to reconfiguring the southbound-only ramp into a reversible ramp. The new entrance at Mercer Street will only be for HOV3+ and transit because it will ultimately connect to the part of SR 520 that is HOV 3+.

HOV designations (2+, 3+, etc.) are set by the state legislature and transportation commission. Non-HOV3+ and transit travelers will continue to use the existing express lanes entrance.

Northbound travelers should also be aware of a change to ramp metering for Mercer Street. There are two sets of ramp meters for drivers and depending on the direction of the I-5 express lanes, one or the other will be in operation.

When express lanes are southbound, all travelers going to northbound I-5 will use the two-lane ramp meters located just east of Fairview Street.

When express lanes are northbound, northbound I-5 mainline travelers will use the single lane ramp meter located at the top of the ramp entering I-5.

Reversible ramps at Mercer and SR 520 will allow for HOV3+ and transit to access SR 520 via a new flyover ramp – already built – that will open after the SR 520 Portage Bay Bridge & Roanoke Lid Project is complete in 2031. In the immediate, the new entrance at Mercer Street will only allow for traffic to continue traveling northbound in the express lanes. When the flyover ramp opens after the Portage Bay Project, the entire connection will officially become reversible and HOV3+ and transit can use the flyover ramp to head east or west based on the express lanes timing.