While driving, I constantly scan the road at least a quarter mile to a half mile ahead to see what other drivers are doing. I also look in my rear view mirror for about 2 seconds and register what other drivers are doing behind me....mainly looking for drivers that are doing 10-15 mph over the limit, or more.
i remeber an incident where I was drivinga work van in Miami on I-95, and a large panel truck was in front of me. A door was up against the concrete barrier to my left. and as the panel truck sped past the door, the wind created by the truck picked the door up, which promptly hit the concrete barrier, the bounced right into my path. Luckily it was a hollow core door, and I hit it. Thankfully it wasn't edge on. I had less than a second to respond.
Since then, I don't drive against the barriers. I take the middle lane when possible. That way, there's a lane on either side if I need to take evasive action.