There are 2 ramps, one from Commerce street, the other from Main 
street.  The one Ruby came down was opposite from the ramp the armored car 
was parked in.  I thought that was common knowledge.  The car Pierce was 
driving went up the opposite ramp the armored car was parked in, Duh!
   Ruby was being honest about why and how he shot at Oswald, I don't 
think he would lie about what ramp he came down just to cover for the cops 
in the basement.  The explanation he used was that he came down the ramp 
when Vaughn's back was turned.  He could just as well used that same 
explanation to cover for the cops in the basement IF he came in through 
the basement door.  Why make up a story about coming down the ramp, 
something that could easily be disproven?  There were many people in the 
basement that could have seen him and would contradict his story for all 
he knew.  If he's caught lying about one thing then that would destroy his 
explanations about everything, no credibility.
   I think the people most likely to lie in this scenario are Vaughn and 
the off duty cop across the street.  Both would want to protect themselves 
against negligence and the reputation of the Police Dept.  It's easy to 
say you didn't see something, you can't prove somebody DIDN'T see 
something, you have to take their word for it, it's a 50-50 proposition.
  It is also very possible they were telling the truth.  Just because you 
didn't see something doesn't mean it didn't happen.  I was looking for the 
solar eclipse that other day, I didn't see it, but it did happen, I was 
just looking from the wrong place.  Vaughn had his back turned so maybe he 
really didn't see him.  The cop across the street, who said he didn't see 
anyone go down the ramp, could have been looking elsewhere at that time, 
it did happen quite fast.