Complex sentence: A preliminary report by the NTSB in April 2011 found that the bus was going 78 MPH at the time of the crash, 28 faster than the posted 50 MPH speed limit, and is the maximum speed of the bus.
Split into simpler sentences: A preliminary report by the NTSB in April 2011 found that the bus was going 78 miles per hour at the time of the crash. That is far in excess of the 50 mile an hour speed limit, and is the maximum speed of the bus.