Re: Tie Spacing
Kevin Strong made a nice entry here: http://ngdiscussion.net/phorum/read.php?1,148340,148862#msg-148862
It references a Nov/Dec 1989 NG&SLG
Stan Ames references the same article and provides similar but different information: https://groups.google.com/forum/#!topic/rec.railroad/Sy-e_FzMksk
According to Wikipedia, the tie spacing is the center to center distance between ties.