Barricades blocked vehicles from part of downtown Roseburg, and dozens of easels lined the sidewalks. Artists were at work. More than 50 artists Thursday set up for a two-hour “quick draw,” a sped-up version of plein air, the French tradition of painting outdoors. Four blocks of Jackson Street were shut for Umpqua Plein Air. The Roseburg Old Town Market took up a fifth block. Fast painters and sketchers replaced parked cars. Downtown architecture became each artist’s subject. Storefronts, lampposts and benches were depicted. Myrtle Creek artist Jan Barba Horn set up her portable studio in a parking space near the …