Whistling while you work takes on a new meaning for one of the world’s largest tunnel boring machines. While Bertha is churning and grinding deep under downtown Seattle, she also sings.

Related: Live updates during viaduct closure

It’s a tune akin to an ice cream truck — a 57-foot high ice cream truck that weighs 7,000 tons.

Manufacturer Hitachi-Zosen pre-programmed the melody into the machine before shipping it from Osaka, Japan. It’s played every time Bertha turns on and starts mining. It lets the 33 workers — all dedicated specifically to keep Bertha going — as well as the rest of the crews in the tunnel, know that drilling is back on.

Seattle’s Alaskan Way Viaduct closed at 12:01 a.m. Friday. The night crew will do testing and maintenance checks on Bertha before the morning crew turns the machine on and starts the push to mine 385 feet forward, under Highway 99. Then, mining will continue 24 hours a day for about two weeks or until that section of tunnel is completed.