Why Are These Truckers Driving Into A Tornado?

Two tractor trailers drive into a tornado
near Eolio, Missouri Sunday. Photo by Kholby Martin.  

Yesterday, there were severe thunderstorms and tornados in and around the St. Louis metro area.

Storm chaser Kholby Martin captured one of the tornados crossing a highway near Eolio, Missouri.

Granted, it wasn't the strongest and most visible tornado in the world, but to anyone traveling along the highway, you can tell there was trouble ahead.  

So in the video you see below, why did two tractor trailor drivers keep going down the road right into the tornado instead of stopping and letting it cross?

One of the trucks went off the road because of the tornado, and the other came THIS CLOSE to tipping over.

Somebody really could have gotten hurt, and it would have taken only a minute to stop and let the tornado cross. Another video I saw of the same tornado taken from the opposite side showed cars stopping to let the twister pass.

Anyway, here's the video: