Segregation of the street occurs when lanes divide the street into multiple rights-of-way. This works well enough mid-block, where all modes of transportation are traveling forward in their respective lanes. The problems occur when one mode of transportation must cross into another mode’s lane, such as at an intersection. Lanes provide a feeling of entitlement to the designated user of the lane; and woe to the “trespasser” who must cross into another’s lane. “When I’m in my designated lane, why should I stop, slow down, or even be aware of others using the street!?” This feeling of entitlement is dangerous for all users of the street. If you’ve ever been in your car and realized too late you needed to cross several lanes of traffic to make a turn, or been a bicyclist trying to negotiate the quirks of lane shifts at an intersection, or been an unsuspecting pedestrian who takes a false step into a bike lane and been subject to a myriad of expletives from speeding cyclists; then you have experienced firsthand the dangers of street entitlement.

Jan Heine of Bicycle Quarterly came to the conclusion that separated bike lanes are actually less safe. He notices a disconnect between the "perceived safety" of bike lanes, and the "actual safety" of these separated lanes. The main problem, Heine notes, is at intersections, where bicyclists must dangerously cross with motorists.

When a street is shared, all users of the street must have a heightened sense of situational awareness. The requirement for every user of the street to be situationally aware will lead to caution and therefore safety. Designated lanes reduce the need for this situational awareness, providing people with a false sense of security while in their lane. Streets designed to demand situational awareness may not be the easiest, nor the fastest means to travel, but provide a safer environment for every mode of transportation on the street.

Our romantic street in Florence is hardly a model for quick and efficient transportation. But that is not the Via’s purpose. The Via die Calzaiuoli is a street to be enjoyed every bit as much as the monuments it connects; it is not simply a means to access those monuments. Planners today need to ask themselves whether they are designing a street for transportation or a via for enjoyment. If their only goal is to move people as quickly as possible, than perhaps segregated streets are the answer. However, if their goal is to have a street that is safely and comfortably enjoyed by various modes of transportation and by pedestrians, than segregated lanes, including bike lanes, may only be moving us farther away from that idyllic Florentine street.