Piles of dirt now, a better carpool lane ride later. Here's what's happening on state Route 16

Perhaps you've noticed those huge piles of dirt along state Route 16 in Tacoma and wondered what's going on there.

The dirt piles and the construction drivers are seeing at state Route 16 and Interstate 5 are part of the Tacoma/Pierce County HOV program, which will connect carpool lanes from the highway directly onto I-5. It's another step in a long run of construction projects on and adjacent to the freeway aimed at making I-5 a better place to drive, especially for carpool drivers.

And if you drive on South Tacoma Way near South Sprague Avenue, you've probably seen the overpass being built.

"They completed a bridge deck pour on the new overpass that goes over South Tacoma Way, so that will take drivers in from route 16 and they'll be able to directly connect to HOV lanes on northbound I-5," said Cara Mitchell, a spokeswoman for the state Department of Transportation.

At the interchange of state Route 16 and I-5, design-builder Skanska has crews building several bridges and ramps, including the overpass across South Tacoma Way for state Route 16 HOV lanes.

That work involves moving about 300,000 cubic yards of dirt and building three "soil nail walls" — Mitchell described them as embankment walls where crews cut into the hillside and put in concrete wall panels to support new roadway alignments.

Some of the dirt is being moved to a project on state Route 167 in Puyallup, Mitchell said.

"They've been doing that over the past month during night hours during the week," she said.

That project is ahead of schedule, and expected to be done in early 2019, Mitchell said.

"Their work zone is huge, and they have room to do continuous work 24/7 without having to close lanes all the time at night," she said, adding that's a result of shifting lanes on I-5, which happened in the spring.

Over the summer, crews will continue work in the area. They also will continue to build bridge structures for southbound I-5 and to carry carpool traffic from northbound I-5 to westbound state Route 16.