In Pennsylvania, it is recommended that you maintain a following distance of at least ____ second(s) behind the vehicle ahead of you.

Explanation

So you can safely avoid hazards ahead of you, the Pennsylvania Driver's Manual recommends the "four-second rule": Maintain a following distance of four seconds behind the vehicle in front of you. You can measure your following distance by noting when the vehicle in front of you passes some stationary object and then counting the seconds that elapse before you reach the same object. If driving conditions are poor or hazardous, you should increase your following distance.