  Street parking spots for automobiles are a scarce commodity in most urban
environments. The heterogeneity of car sizes makes it inefficient to rigidly
define fixed-sized spots. Instead, unmarked streets in cities like New York
leave placement decisions to individual drivers, who have no direct incentive
to maximize street utilization.
  In this paper, we explore the effectiveness of two different behavioral
interventions designed to encourage better parking, namely (1) educational
campaigns to encourage parkers to "kiss the bumper" and reduce the distance
between themselves and their neighbors, or (2) painting appropriately-spaced
markings on the street and urging drivers to "hit the line". Through analysis
and simulation, we establish that the greatest densities are achieved when
lines are painted to create spots roughly twice the length of average-sized
cars. Kiss-the-bumper campaigns are in principle more effective than
hit-the-line for equal degrees of compliance, although we believe that the
visual cues of painted lines induce better parking behavior.
