situational irony
Situational irony is when something happens that is opposite of what is expected. The poem opens with shards of glass all over the roadway. This indicates that there has been a car accident that probably shattered a headlight or two, maybe even one of the car windows. This would normally be seen as a negative; however the speaker sees beauty in the glass on the road. The speaker compares it to sparkling stars. The speaker even notices this irony in the last 3 lines with "I couldn't help but think/How someone else's tragedy/could be so beautiful to me."
Dramatic irony is when something is said but really means the opposite. External conflict is a problem that happens between a character and something outside of the character like another character, a force of nature, or society. Internal conflict is a problem that happens within the character. It usually involves the character making a difficult decision or learning something important.