“We all discovered what a powerful vehicle it is to have her singing these songs, and to calm the flurries of notes down a little bit,” he added. “It’s there and it’s hiding, bubbling underneath, ready to come out and gobble up everything at any point. But another thing about it is knowing that you can do that — but not doing it.”

Douglas — whose dobro and steel guitar often answer Krauss’s voice with keening, sighing alternate melodies — has long been a first-call Nashville studio musician, bandleader, collaborator and producer. Among his recent projects are “The Set,” his 2024 album as a leader; recording with Celtic musicians in Scotland for the Transatlantic Sessions series; and producing an upcoming album for the Nitty Gritty Dirt Band.

The other Union Station members also stayed active between albums. Krauss released “Windy City,” a more mainstream country album, in 2017, and in 2021 she and Led Zeppelin’s Robert Plant released their second duet album, “Raise the Roof,” followed by a tour. (Their first album, “Raising Sand,” won the Grammy for album of the year in 2009.) Bales and Block toured with Krauss for “Windy City,” played studio sessions, wrote songs and released instructional videos.

“Everybody’s always gone and done their own thing and had a very busy career outside of this band,” Krauss said. “When we come back together, we’ve lived all these other places, and it just makes it stronger. I’ve always felt like, you know, life sounds good on people.”

“Arcadia” marks a major lineup change in Union Station. For three decades, Dan Tyminski traded off lead vocals with Krauss, providing a grainy, rough-hewed contrast to the delicacy of her voice. He won Grammy Awards with Union Station and on his own, notably for “Man of Constant Sorrow” from the 2000 Coen Brothers movie “O Brother, Where Art Thou?”

During the sessions for “Arcadia,” Tyminski decided he wanted to continue his solo career instead of joining Union Station on tour this year. “Nobody wanted Dan to go,” Douglas said. “But Dan’s got a thing he’s got to go do, and we all respect that.”