From the owner's Facebook page describing the events just prior to the accident...
"The highway in my direction of travel divided at a fork, with the #2 right lane changing into the exit lane, and the #1 left lane remaining the lane for thru traffic. I was travelling in the #1 lane.
My left hand was grasping the bottom of the steering wheel during the drive, my right hand was resting on my lap. The vehicle showed no signs of difficulty following the road up until this fork. As the gore point began, approximately 8m before the crash barrier and end of the fork, my Model 3 veered suddenly and with great force to the right. I was taking a glance at the navigation on my phone, and was not paying full attention to the road. I was startled by the sudden change in direction of the car, and I attempted to apply additional grip onto the steering wheel in an attempt to correct the steering. This input was too late and although I was only a few inches from clearing the crash barrier, the front left of the vehicle near the wheel well crashed into the right edge of the barrier, resulting in severe damage...."
"By looking at my navigation and by not having both hands on the wheel, I was not paying full attention to the road while the vehicle was in Autopilot and was not following Tesla’s directions in regards to the correct use of the software. I want to make it clear that I take responsibility in regards to my actions."