Crescendo to an error

A certain private parking area near my brother's apartment includes fold-up pedestals that the spaces' owners can upraise to defend them from other motorists. Each pedestal folds up into the middle of its parking space, where you lock it into place with a key. The distance between pedestals in adjacent spaces then becomes just one pedestal diameter less than the width of the space. Now instead of just blocking your space, the interloping vehicle blocks two spaces:

http://www.sevenextraeyes.org/andy-social/cars.jpg