How long does it normally take to get airside at BWI from the time you arrive at BWI Amtrak station? I know the shuttle runs every 15 minutes; and the ride takes about 10 minutes, so, would it be safe to assume around 25 minutes just to make it to the terminal building, and then the time it takes to clear security? If security only takes 15 minutes, would it be too optimistic to assume one could get airside in 40 minutes?