New NB South Dearborn off-ramp in Seattle first in the world to use earthquake-resistant concrete

Getting to downtown from south of Seattle got a lot easier -- and perhaps safer -- for some drivers Tuesday morning.

The new off-ramp near the stadiums opened in time for the morning commute, opening about two weeks after the new state Route 99 tunnel opened.

In addition to offering a convenient route to downtown Seattle for northbound travelers, the off-ramp's bridge is the first in the world built with flexible metals and bendable concrete.

That means, this chunk of road will sway with earthquakes, then return to its original shape.

"In the past, the paradigm has been 'no collapse.' That's what we were designing for," Tom Baker said in a 2016 video by the Washington State Department of Transportation. Baker is a bridge and structures engineer for WSDOT. "In the future, we can be designing for 'no damage.'

"Immediate use by emergency vehicles, commerce, the public. If that comes true, it would be a giant leap forward."

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Engineers developed reinforcing bars called shape-memory alloy (SMA) bars that are able to return to their original shape after being bent -- like a pair of metal-framed eyeglasses -- and a highly flexible concrete made with a lot of fibers, which doesn't crack and fall away after a period of stress as easily as traditional concrete.

The idea of combining the two materials began development over 15 years ago at the University of Nevada - Reno's earthquake engineering laboratory.

"In the laboratory, we have really pushed things to limit. We have simulated very strong earthquakes, well beyond the kind of earthquakes that are likely to occur during the lifespan of the bridge," M. Saiid Saiidi, professor at the University of Nevada - Reno said in the video.

RELATED: 'The safest place to be': Why the new SR-99 tunnel will withstand large earthquakes

So why does Seattle get the first bridge of this kind? In part, WSDOT said in a blog post, because it is a small bridge. The materials used cost up to 90 times more than standard steel and concrete.

"The Federal Highway Administration gave the go-ahead for this real-world test, and a federal grant paid for much of the additional costs," the blog post states.

The bridge is not the only area of the new SR-99 route that has been built with earthquakes in mind. The new tunnel is designed to withstand an earthquake with a magnitude 9.0.