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Inside the new ‘state of the art’ SR 99 tunnel

Freshly painted lane stripes on the northbound (lower) deck of the SR 99 tunnel (WSDOT)

When the new SR 99 tunnel opens Monday it will be four years late and millions over budget.

RELATED: WSDOT lays out new routes for SR 99 tunnel

But after all that, we’ll be getting a state-of-the-art tunnel that has high-tech fire suppression systems, traffic cameras, and even transitional lighting that changes based on the time of day.

“Our design of the tunnel is state of the art,” the tunnel’s project manager, Brian Russell told KIRO Radio.

That design includes lanes wider than the ones on the now-closed Alaskan Way Viaduct.

“It’s almost wide enough for three full lanes — if you were driving on the viaduct, it would fit three cars,” said Russell. In total, there are two levels, with two lanes in each direction, with the added space left to allow room for emergency vehicles.

From a safety perspective, no expense was spared. The new tunnel is designed for a 9.0 earthquake, and is composed of 1,400 concrete rings which hold and yet create flexibility. After moving with the earthquake, the tunnel would return to its original shape.

“Our design allows for those movements as the ground moves and dissipates energy,” Russell described.

“The SR 99 tunnel would be the safest place to be in Seattle during and after a big earthquake,” WSDOT’s Dave Sowers said in early January.

In the case of a fire, the tunnel is equipped with automated heat detection, while also being monitored by operators who can alert the system to a fire themselves should that become necessary.

All of this amounts to a two-mile route that operates less as simply a tunnel, and more as a high-tech facility.

“The whole facility is like a big building designed for cars — it has all the systems you might have in a modern building,” said Russell.

RELATED: Date set for opening of new tunnel, end of Viadoom

The new SR 99 tunnel is set to officially open the morning of Monday, Feb. 4. It will be toll-free to start, before enacting a tolling system sometime during the summer.

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