Would you drive into a black hole at 70 MPH, unsure of what was on the other side?  Many drivers do exactly that in foggy conditions, often with serious, even fatal consequences.  They certainly must believe that what they can't see can't hurt them. They are wrong.  From 70 MPH, with normal reaction times and dry road conditions, it takes over 200 feet to stop.  That's about 15 car lengths. 
    If a driver's visibility is only 50 feet in the fog, and an accident blocks the road, at 70 MPH, the driver will not even begin to apply the brakes before a full speed collision occurs.  The only prudent course of action is to drive at a speed compatible with the visibility, road conditions and driver reaction time.  With 50 feet of visibility on a dry surface, maximum speed should be about 20 MPH.  At that speed 40 foot stop is the best you can hope for.  So remember! When visibility is limited, reduce speed so that you can react and stop within the distance you can see.  It could save your life.  This is Don Alexander for The Mountain Driver on KBHR 93.3 FM.