Wow. That sounds like a blast. Have heard some Barbershop & knew it is a US college tradition, but had no idea about the brigades.
As a curious aside, saw a thing on television just this evening about a Portuguese musical tradition which exists in their universities. The style & tunes are very different to Barbershop, and they make use of string instruments as well (though everybody has to sing) but they too have familiar repertoire and appear at various events on campus, as well as competing with other university troupes.