To avoid panic stops or sudden turns, you should look ahead at least

To avoid panic stops or sudden turns, you should look ahead at least 12 seconds. That is, you should look ahead to where your vehicle will be 12 seconds from now. (At 30 mph, your vehicle will travel a little over one block in 12 seconds.) This 12-second rule allows you to watch traffic patterns and react to changes. However, at freeway speeds, you should look ahead at least 20–30 seconds. (At 70 mph, your vehicle will travel 3,080 feet in 30 seconds – more than half a mile.)