Although soaked in the hard bop style that dominated the mid 1950s thanks to musicians such as Art Blakey, Max Roach, Clifford Brown, Freddie Hubbard, and Hank Mobley, 'Blue Train' marks a departure from conventional bop harmonies. The songs 'Moment's Notice' and 'Lazy Bird' make use of chord changes known as 'Coltrane changes', which Coltrane further explored in later albums.
Coltrane changes involve the shifting of key centres by the interval of a major third. It is speculated that Coltrane was inspired to experiment with such a progression after working with Thelonious Monk's unusual approach to harmony, and also by Miles Davis' conception of modal jazz.
On 'Blue Train', Coltrane is on the verge of inhabiting his future musical persona, but is still firmly planted in hard bop. His combination of blues riffs, bebop lines, sheets of sound, and Coltrane changes crackles with volatile energy, as though each element were a reactive chemical.