We're just months away from the opening of the new State Route 99 tunnel under Seattle.

The project is years behind schedule, in part because of Bertha.

You might know the tunnel boring machine because of her infamous troubles underground, but you might not know how Bertha got her name.

Six years ago, Darryl Elves' fifth-grade class at Poulsbo Elementary School won a contest to name the boring machine.

They chose "Bertha" after Bertha Knight Landes, who was elected Seattle mayor in 1926 and was the first woman to lead a major U.S. city. Elves said his students saw that Landes was "a remarkable person" in Seattle's history.

"It was a slam dunk," Elves remembered.

Elves is now retired, and has been for about four years. His fifth-grade students are now high schoolers, and many will soon be able to drive the new tunnel themselves.

RELATED: Why the tunnel is three years late

Bertha Timeline

The contest to name the boring machine was in 2012.

Bertha began digging in July of 2013. But by December of that year, she was in trouble. The giant machine was overheating, and she dug in fits and starts as managers attempted to figure out what was wrong.

In January 2014, Bertha stopped and didn’t start digging for another two years. The problems were tied to seals and bearings.

Bertha resumed the dig in January 2016.

The tunnel is expected to open in early 2019. It's original opening date was December of 2015.

Also see | Seattle tunnel tested for full-scale emergency