The Highway 99 tunneling machine has passed the one-mile mark as of this morning, according to WSDOT. It’s also made a new video showing how the machine is steered along its designated path underground, considering there’s no GPS:

The machine is at its deepest point – around 200 feet underground – with just under 4,000 feet remaining on the route, which is shown on this map, along with the machine’s approximate current location. The most recent timeline says that absent any further major problems, the tunnel will open in 2019.