The best practice today is to have urban streets with no more than three moving lanes (one for each direction of travel and a shared one for turning). The city of Chicago recently rebuilt sidewalks and reconfigured the roadway on a stretch of Broadway in Uptown. Instead of converting some of this overly wide right-of-way to more people-friendly uses, the street gained travel lanes.
Three lane streets are safer than those with more lanes and can carry about as many motor vehicles. Having more encourages constant lane switching, each maneuver an opportunity for a crash. In the new configuration on Broadway, there are as many as six moving lanes (see middle photo, looking north from Montrose Avenue).
Broadway could be Chicago's Lincoln Road (in Miami Beach) or Ramblas (in Barcelona). Limiting the travel lanes to three, one could create a wide median that would have room landscaping, places to sit, and kiosks for small businesses (see the top and bottom images of a proposal for the median at Broadway and Argyle Street). Let's make Broadway a living room, market place, and garden for Uptown.