Q & A: What to know about the new SR 99 tunnel

Q & A: What to know about the new SR 99 tunnel

Here's what you need to know about the new SR 99 Tunnel.

When will the new SR 99 tunnel open?

WSDOT confirmed it will be fully open on Monday, Feb. 4 in time for the morning commute. The process will begin in the early morning and will occur ramp by ramp over the course of several hours.

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How many lanes does it have?

The two-level, two-mile tunnel has two lanes in each direction, with an eight-foot safety shoulder.

What is the speed limit?

45 mph

How will my route into downtown Seattle change after the tunnel opens?

Once the two-lane, two-mile tunnel opens, SR 99 drivers will have a direct route from the stadiums to near Space Needle, but there are no mid-tunnel exits or entrances. There is a south portal near the stadiums and a north portal in South Lake Union.  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.

>>But northbound SR 99 drivers be aware, the exit to take surface streets into downtown, just south of the tunnel entrance, will not be open until at least a week after the tunnel opens. 

Find detailed maps and explanations on WSDOT's SR 99 Tunnel website.

Will I have to pay tolls on the tunnel right away?

The tunnel will be toll-free for several months after it opens.

When will the tolls begin?

As early as summer 2019.

How much will the tolls cost?

Weekends: $1


  • 6 – 7 a.m. - $1.25
  • 7 – 9 a.m. - $1.50
  • 9 a.m. – 3 p.m. -  $1.25
  • 3 – 6 p.m. - $2.25
  • 6 – 11 p.m. - $1.25
  • 11 p.m. – 6 a.m. -  $1

What if there's a crash or a car breaks down in the tunnel?

There's an eight-foot shoulder for cars to pull over, if possible, or for emergency vehicles to use.

What if there's an earthquake?

The tunnel is designed to withstand a roughly a 9.0-magnitude earthquake along the Cascadia Subduction zone. "Geotechnical and structural engineers agree that tunnels are among the safest locations during an earthquake. This is because earthquake waves are most severe above the surface. Underground structures like tunnels move with the soil, while above-ground structures sway back and forth," WSDOT said on it's website.

What about flooding or a tsnuami?

The tunnel is designed to remain watertight after an earthquake, so people can be evacuated safely. WSDOT says the Seattle Seawall Project provides additional earthquake and tsunami resilience.

"It is highly unlikely that a tsunami could overtop the seawall and reach the tunnel (WSDOT and City of Seattle analysis found this could only happen if a tsunami coincided with a very high tide – a combination of events estimated to occur only once every 6,000 to 24,000 years). If that were to happen, Washington’s early warning system and the tunnel’s real-time traffic technology would immediately restrict vehicles from entering the tunnel," WSDOT said.

If water did enter the tunnel, drains and pump systems capable of pumping up to 300 gallons per minute would help to quickly remove the water.

What about another emergency?  Will I be able to get out?

If an emergency requires people inside the tunnel to leave their vehicles and get off the highway, there are doors every 650 feet leading to safe areas to wait or leave the tunnel. There's also an exit path that runs the length of the tunnel that's equipped with ventilation and fire suppression systems.

In the event of an emergency, electronic signs, a public address system and an AM/FM override system would be used for messages.

How would anyone on the outside know if something was wrong in the tunnel?

WSDOT said the tunnel will be monitored by operators in the tunnel control center 24 hours a day, using an extensive system of 300 incident and security cameras that are able to detect anything unusual inside.

The real-time technology will also be used to let drivers know about slowdowns caused by stalled vehicles or crashes via overhead signs.