Nearly four months after completing its journey into the disassembly pit after digging the two-mile-long State Route 99 tunnel, tunnel-boring machine Bertha is half-dismantled.

Last month, we saw a large chunk of Bertha’s front-end disassembly, including cutter spokes—the more visible and recognizable part of the machine. Now, enough work has been done taking apart the front of the machine to start tackling the drill from both the disassembly pit and inside the tunnel, Washington State Department of Transportation (WSDOT) says.

After crews got far enough along with cutterhead disassembly, they were able to use Bertha’s thrust rams one more time to pull additional gear forward.

That work isn’t visible on the time-lapse cameras, so WSDOT released a new video showing a month’s worth of work on one of the machine’s three backup cars inside the tunnel. (We’ve embedded it below.)

“For context, there’s more machinery behind the camera than there is in front,” said WSDOT spokesperson Laura Newborn in an email. “It may appear as if the work is almost complete, but there is more to go.”

Meanwhile, out in the daylight, Bertha’s cutterhead is significantly further dismantled. WSDOT’s time-lapse cameras of the disassembly show the cutterhead completely gone and almost a bisection of the main portion of the drill.

Watch the behind-the-scenes disassembly below, along with a view of the end of the tunnel.

Bertha officially finished the length of the two-mile tunnel, which will take cars past downtown along State Route 99, on April 4. That was a few years behind the original schedule, which estimated the tunnel would open in December 2015.

An adjacent bridge that will carry cars past the tunnel and into downtown was completed in late May.

Current project estimates have the tunnel opening for traffic in early 2019.