The road untraveled is starting to look like an actual road.

Deep beneath Seattle, the SR 99 tunnel project continues at a pretty rapid pace. Perhaps not as rapid as it appears in a new time-lapse video released Thursday by the Washington State Department of Transportation.

The video shows off the ongoing construction of the lower, northbound portion of the double-decker highway that is being built inside the tunnel whcih was carved from near the sports stadiums at the southern end of downtown Seattle to near the Space Needle at the northern end.

SR 99 tunnel
A Seattle Tunnel Partners crew member works in a pocket between concrete panels that form the northbound (lower) roadway of the SR 99 tunnel. The pockets indicate the location of steel cables used to lock the panels together so they act as a cohesive unit. (Flickr Photo / WSDOT)
SR 99 tunnel
A Seattle Tunnel Partners worker ensures that a northbound (lower) roadway deck panel fits in a very tight space. (Flickr Photo / WSDOT)

The lower roadway is being pieced together one 22-ton panel at a time. The pre-made panels are trucked into the tunnel and a special heavy duty crane lifts them into place before they are joined together to form the finished highway.

The concrete for the upper, southbound roadway was poured in place. That portion of the highway was recently completed, which will allow panels for the lower portion to now be delivered through the north portal of the tunnel, with 3,000 feet of roadway left to build.

Check out WSDOT’s progress tracker to see what’s ahead in the ongoing project, which is expected to open to traffic as soon as this fall.

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