I doubt anyone can quantify how many slaves escaped via the UGRR, because many of the activities were hidden. Although we have published sources like Still's book and others, there are numerous stories that have yet to be told.

One of the largest obstacles that the museum is going to face, and anyone attempting to research and document UGRR activities, is that it was shrouded in mystery and has been absorbed into local folklore. I've read numerous accounts of people claiming to own a house or know of a home used for UGRR activities, only to learn that the home was built in the 1880's or later. As I understand it, the museum will collect and research much of the stories. However, I'm not clear that it will focus on UGRR activities beyond the boundaries of Ohio.

And in any event, much of what you seek, probably won't be revealed until some later date. At this point they probably are focusing on fundraising, collections acquisitions, development and building the museum.