"Freight Train" is a short folk guitar piece that employs a technique known as a bass run. This technique is a single-note line — played by the thumb — that leads to the next chord and serves to break up the monotony of a repeated pattern. To play “Freight Train,” you need to know how to play a Travis-style solo; how to play hammer-ons; and how to sound like a simple hobo while playing a sophisticated fingerpicking arrangement.
A bass run breaks up the monotony in measures 4 and 8. In measure 9, you’re fingering an E chord, and you can use your first finger, flattened into a barre, to play the 1st string, first fret. Use your left thumb, wrapped around the neck, to finger the 6th string in bars 11 and 12. Measure 14 features a fancy little trick — you hammer a treble note at the same time that you strike a bass note. In measure 15, the bass alternates among three notes, not two.
Don’t let the simple nature of "Freight Train" deceive you; the guitar parts here make them sound full and complete. After you get these arrangements down, all you need is the requisite flannel shirt and hiking boots and you’re on your way to a career in hoboing, labor organizing, and political protest.