Space Cushion – Your Margin for Error on the Road

Blurred view  of car windshield with digital warning sign indicating vehicle is too close to vehicles in front.

We’ve all heard a number of safe driving principles such as avoiding distracted driving, following speed limits, never driving impaired, and the hazards of road rage.  But there is another principle that deserves just as much attention: Space Cushion. What is space cushion?  If you think it’s part of a comfy seat for astronauts please read on.  Space cushion is the area between you and other vehicles on the road, in all directions.  There should be plenty of space in front, behind, left, and to the right of your vehicle.  It is essentially the safety margin, or margin for error, not just for yourself, but for other drivers you encounter as well.  Let’s take a closer look.

Keeping an adequate distance between us and the vehicle in front of us is the easiest part of our space cushion to control. The National Safety Council (NSC) recommends following the 3-second rule; allowing a minimum of 3 seconds of travel between our vehicle and the vehicle we are behind.  When the vehicle in front of you reaches a landmark (a tree, light post, road marking, etc...) start counting. If you reach the same landmark before 3 seconds have elapsed, you are too close and should increase your following distance. This distance should be increased even further for large vehicles or when driving in bad weather.

The next principle of space cushion is keeping adequate space to the left and to the right. To do this we should avoid driving alongside other vehicles at the same speed. As a rule of thumb, you should be completely in front of, or behind vehicles in other lanes of traffic. Not only does this reduce the changes of being in their blind spots, but it also gives you increased reaction time should these vehicles suddenly swerve or make an unexpected lane change. You might be allowing 3 seconds or more of cushion from the vehicle in front of you, but if there are vehicles to the left or the right of you, try slowing down for a couple seconds to open up that space as well. 

This separation, or cushion, also applies to other hazards on the road.  As we navigate busy streets we should attempt to “separate hazards.”  Drivers should avoid reaching two hazards at the same time.  For example, passing a cyclist at the same time we meet a car coming in the opposite direction.  Slow down slightly and let the opposing traffic clear before passing the cyclist.  This way you’re maintaining the space cushion from both hazards.

Last but not least, what about the driver behind you?  You know, the one who follows the “1-second rule.” This is not only annoying, but extremely hazardous to both drivers.  What can be done to maintain adequate space cushion with this vehicle?  This one is trickier to be sure.  You can’t control other drivers.  Just remember the NSC definition of defensive driving:  “Driving to save lives, time, and money in spite of the conditions around you and the actions of others.”  But there are a few things you can do.  For starters, speeding up is not the answer.  Few tailgaters allow more following distance just because the vehicle in front of them speeds up a bit.  Rather, you should allow even more space between you and the vehicle in front of you.  If this vehicle stops suddenly, that extra distance would allow you to come to a more gradual stop.  This might provide the extra time the driver behind you needs to avoid rear-ending you.  In addition, this extra cushion often encourages the tailgating driver to pass you which would allow you to better control the distance between your vehicles.  Pulling over to a safe location and allowing the driver behind you to pass is often a good option as well.

Check out additional safety resources within the Safety Director, or many offered by the National Safety Council, the National Highway Traffic Safety Administration, or the Insurance Institute for Highway Safety.