Watch the The Train online guitar lesson by Robbie Calvo from The Rhythm Architect
Playing the riff an octave above is a great way to add depth to the music. I chose to do this at the 7th position because of the double-stop 6ths I end the phrase with. You'll notice that the major 6ths in this guitar part are actually an inversion of the minor 3rds in part 3. Check out how cool the two ideas sound together, now that's magic!
Please remember that you can build the groove by playing each of the ideas presented here in turn to keep the musical content interesting without ever being too complex or redundant, especially if you are the only guitarist at the session.