In one aspect of the invention is a method for reducing crosstalk and maintaining clearances between traces on a printed circuit board design. Crosstalk caused by placing traces a virtual printed circuit board are reduced by placing artificial obstructs, called spacers, between traces and/or between traces and nets to create a user-specified clearance between the traces and/or nets. As additional traces and/or nets are added to the virtual printed circuit board, the spacers are dynamic and adjust accordingly to maintain the specified clearances.