These are supposed to save lives, but not according to one news story: http://www.wxyz.com/news/national/popular-guardrail-lining-roadways-more-dangerous-than-earlier-model-study-says
I think we've discussed this situation in another thread.
I'm not aware of the changes in the size of the end treatment, but I do know that Kentucky has been actively installing this general type of end treatment on high-speed roads, to replace the "Texas Twist" method that has a tendency to launch cars into the air if they are struck just right.
A couple I know lost two sons in a single-vehicle wreck where they ran over a "Texas Twist" end treatment. The boys had been to Indianapolis for a concert and were on their way home when the driver fell asleep. The wreck was only about 35 or so miles from their home.
QuoteAs the 36-year-old drove alone on a North Carolina highway, his Isuzu Trooper veered sharply and slammed head-on into a guardrail...
Don't you hate it when the vehicle does that? Don't the tires, or the driver. Blame the vehicle. Uh-huh.