As acronyms for single-issue organizations go, ROAR — that would be Rags Over the Arkansas River — is pretty good. In case the “rags” part doesn’t make it clear, the group is opposed to the execution of the work that environmental artists Christo and Jeanne-Claude intend to erect over a 40-mile section of the Arkansas in south-central Colorado. The piece will comprise more than 900 permeable, translucent panels of silver fabric suspended above the water in eight sites between Canyon City and Salida. The artists intend to display “Over the River” — pending approval of the various permits they’re already years into the process of seeking — for two weeks in the summer of 2012.

By then, Christo and Jeanne-Claude will have spent two decades working to bring their latest feat of artistry and engineering to fruition. A new touring show, kicking off its run at the Phillips Collection, shows us just how costly, time-consuming, and complex the “how” is. The “why” you must supply for yourself.