Having been an Atlanta resident for 50+ years, I can tell you that the only way to take I20 west from I85 South is via I285 west. Just follow the signs to Birmingham. The advice to to avoid I285 is poor at best. That will take you into downtown Atlanta with multiple exit only lanes. narrower lanes than I285, and drivers who never learned what merging and turn signals meant. True, the big trucks cannot travel inside I285, but why drive an extra 20 miles to avoid trucks on I 285 that you will be traveling for only 16 miles. Besides, the big trucks are already on I75 and I20!!!!!!