Sad to hear, may he R.I.P. He will be missed both on here and in the local farming community.
From reading the description of the accident site, that was my first thought as well.This just pure speculation on my part, but Jeff had a known heart condition. He was hospitalized several times because of it since I've know him.
This intersection was very near his house. He knew it well. The accident happened in broad daylight, around 9 AM.
Just a guess.