Watch the Train Turn Around online guitar lesson by Massimo Varini from Rhythm Factory: Acoustic Rock
D major played with a drop D tuning. As in other examples, if intros and verses are in a major context, the bridge is based on the relative minor of the key. So this example is in Bm (sixth degree of D major). Pay attention, the bass part and the high part of the voicings are not changing at the same time.