Made some relatively major changes to the design. Widened the template by 4 cells to allow placement on more varied terrain. Added placeholders for 4x3 parks at each corner of the underpass.

Added a 1-tile separation between the two halves of the highway. This increases the space between frontage roads from 13 to 14 (which works nicer with most city layouts) and allows power lines to be run down the middle if necessary.