A sliding gate opens by sliding sideways across the opening. It does not swing out, so it needs no clear space in front. It does need room to slide into along the fence, called the runout, usually 1 to 1.2 times the width of the opening. There are two main types: tracked gates that run on a rail set in the ground, and cantilever gates that hang from rollers on a post with no ground track.
Residential driveway openings in Australia are usually 3500 to 6000 mm. Commercial industrial openings can run to 12,000 mm and beyond. Cantilever gates win on driveways that must stay clear: low-clearance vehicles, drainage runs, leaf debris that would jam a ground track. The trade-off is roughly 30% extra steel for the counterweight section.
CAD60 supports both styles. The engine recomputes overhang, counterweight length, and rail position from the opening width you enter.