When you're planning and building benchwork, be sure to leave enough clearance around your track for your largest trains to pass through unobstructed. Cut away sections of wood and place turnouts and turnout motors so they won't block your trains. Run your tallest, longest and widest trains through narrow sections until they will pass through without problems then leave a little extra room for future acquisitions. If there isn't enough clearance before you add scenery, then you'll never have enough clearance.