Where'd you get your info? I've been in the tunnels half a dozen times and can confirm there are no rails! Check out this book, it's the most up to date and complete one about the subway. It's also a free e-book from the Library if you want to go that route.
My friend (Cincy native) just wrote a book about it. It's really comprehensive. If you're into this sort of thing pick up a copy, he could use the support!
http://www.amazon.com/Cincinnatis-Incomplete-Subway-Complete-History/dp/1596298952