Seattle's new SR 99 tunnel
Seattle’s newest tunnel will provide a direct route on SR 99 between the stadiums and the Space Needle. It is the largest double-deck highway tunnel of its kind in the country, and will feature modern safety and operations systems.
Know your new tunnel:
- Opens as soon as this fall
- Two miles long
- Two lanes in each direction, plus an eight-foot safety shoulder
- South portal near stadiums; north portal near Space Needle
- No mid-tunnel exits or entrances
- Will not be tolled upon opening; tolling starts in 2019 on a date to be determined
Drivers that today use the Alaskan Way Viaduct or Battery Street Tunnel will have new routes and options for getting to and through downtown Seattle.
Tunnel route with nearby surface street options
This map shows the tunnel's path beneath downtown Seattle and major surface street options that can take you to and from both ends of the tunnel (the portals).
Drivers will be able to get on and off SR 99 at both tunnel portals, and decide whether to take the tunnel or enter downtown and adjacent neighborhoods.
The tunnel’s south portal is just west of CenturyLink Field. On- and off-ramps in both directions will connect SR 99 to the stadiums, Alaskan Way and Colman Dock along the waterfront, and downtown Seattle. Just to the east is the start of I-90 and connections to I-5.
Coming northbound on SR 99, the exit to downtown and Alaskan Way will be the last exit before the tunnel. That ramp will end at a new intersection of South Dearborn Street and Alaskan Way South (shown below). Drivers heading to southbound SR 99 from downtown or the stadiums will use Alaskan Way or First Avenue South to reach the new southbound on-ramp at this same intersection.
The tunnel’s north portal sits just east of Seattle Center. On- and off-ramps will provide connections to nearby Denny Way, Dexter Avenue and Mercer Street, as well as routes to reach I-5.
Southbound drivers can take the off-ramp to Denny Way and downtown, which ends at the intersection of Aurora Avenue North and Harrison Street. From there they can head to Seattle Center (west), South Lake Union (east), or into downtown (south)
Drivers seeking to head north on SR 99 will use Aurora Avenue North or Harrison Street to reach the northbound on-ramp.
Three blocks of Aurora Avenue North, between Harrison Street and Denny Way, will be reconnected as part of the demolition project (see below). The approach to the Battery Street Tunnel will be brought up to grade and rebuilt, and John and Thomas streets will be reconnected east-west across Aurora Avenue North. Learn more about this work on our demolition page.
The tunnel will feature two lanes in each direction. Unlike the Alaskan Way Viaduct's extremely narrow shoulders, the tunnel will have an eight-foot shoulder in each direction for vehicles to pull over in case of breakdown or crashes. Long, gentle curves will allow for safe sight distances.
The tunnel will be built to modern earthquake standards and feature smart systems that work together to keep traffic moving safely. In the event of an emergency, exits every 650 feet provide shelter and escape routes, while a state-of-the-art ventilation system assists first responders and fights fire and fumes.