Look again at the photos. Look closely, now...
Pay particular attention to the roll angle of the track as it enters the tunnel. Indeed, it looks like there is no where near enough clearance above and to the left of the track. But notice that the track is tilted over at a *significant* bank angle, and that by offsetting the tunnel to the one side of the track, there is plenty of clearance to be had where it needs to be.
--Dave Althoff, Jr.