Perhaps an aerial view looking east might help--
Mr. BALL. First time you saw the President's car it was going underneath?
Mr. WHITE. Yes, sir.
Mr. BALL. What did you do after that?
Mr. WHITE. As soon as the train passed I went over and on the northwest side of the Depository Building.
How could White have seen the president's car 'going
underneath' if ---1. He was on the west side of the underpass and 2. If there was a train going by?
The train array must be 50 or 60 ft across and the limo was absolutely gassing it by the time it reached the west side ..so we are talking about 5-10 seconds not 5-10 minutes for a train to pass by.