How does Amiri Baraka use imagery in Dutchman?

The imagery is consistent with the setting. Dutchman takes place "in the flying underbelly of the city:" in a subway train. Throughout the play, the audience is made aware of the setting through the roar of the train and the flashing lights as it speeds and slows and occasionally stops for passengers. Twenty-year-old Clay, a black man, is riding the train. At first only his seat is visible. Before the action of scene gets underway, he exchanges a fleeting smile with an unknown face on the platform and then goes back to reading his magazine.