Meaning of "hazzas"
My understanding is that a "hazza" (an exclamation of joy not unlike "hooray" or "hurrah") would come from people gathered on the platform observing the train's arrival, their sound being overwhelmed by the train's whistles. Merriam Webster and the Oxford English Dictionary spell it "huzzah" but I'd suggest in this context they are one and the same. See http://www.merriam-webster.com/dictionary/huzzah.