CCTV footage shows the moment a San Francisco Muni train operator fell asleep at the controls before crashing straight into another train. The driver appears to nod off for around 20 seconds before the collision, which shattered the windshield near the San Francisco Zoo. Both trains were empty, and the SFMTA has said the crash was caused by operator fatigue. (via: @reuters) #reelheadline #pubity #viral