text: Traffic roars down the broad Corso Umberto I to the pivotal Piazza Municipio to serve the docks or spin off into the commercial district behind Santa Lucia , the teeming historic center of Spaccanapoli , or the residential districts of Vomero and Posillipo .
  
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  Traffic flows down the Corso Umberto I at very fast speeds , making it the most dangerous road in the region .