About 1:20 p.m. EST, the rumbling of traffic on 49th Street was broken by the upbeat sounds of a horn trio. Three members of Local 802 of the American Federation of Musicians, outfitted with a trumpet, trombone and French horn, stood at the end of the barricade, piping out tunes. At the end of their first song, the writers let out a cheer and hearty applause.