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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883


Spatial perception for driving

Human spatial perception develops naturally.  Ability to judge and react to size, distance, depth, et cetera is “built-in” at birth and improves with environmental interaction.  But those skills are somewhat compromised when it comes to motor vehicle operation.

Humans are naturally still, walking at 2 to 4 miles per hour, or running at speeds of 6 to 15 mph.  Our inborn senses are not coded for moving in and among motor vehicles at higher speeds.

To merge, pass and generally interact with autos, we must customize our spatial perception for driving.  While such readiness may not come naturally, it can be developed with practice.

For example, on a level roadway, observe a landmark then travel one mile per your odometer and re-view the landmark in your rearview mirror to visualize what a mile looks like.  Or, choose a point that you think is one mile ahead and check, according to your odometer, how close your estimate was when you arrive at that point.

Soon, you’ll be an expert at judging distances of one, one-half and one-quarter mile.  Also keep in mind the concept of moving at a-mile-a-minute when you are doing 60 mph.  We are regularly forewarned of upcoming freeway exits at one-quarter or one-half mile in advance.  Being able to judge these distances improves your ability to properly position a vehicle within traffic for exit maneuvers.

You might be making a left-lane pass when a sign indicates that your exit is a half- mile ahead.  At that point, an astute driver will know they have about 30 seconds to finish the pass and move to the right-hand lane — no need to panic or abort the pass — simply begin counting seconds, knowing that you have until the count of 25 or so to make your exit.

Distance determination is easier when coupled with time.  That’s why experts express following distance in terms of time nowadays.  Old school driving guides recommended 20 feet of following distance for each 10 miles per hour of vehicle speed.  Later, that guideline was simplified to one car length for each 10 mph.  But at 70 mph, seven car lengths are difficult to accurately assess.

Currently, suggested following distance is determined in terms of seconds.  A 2-second gap behind another vehicle is specified for speeds up to about 45 mph, and a “space” of 3 to 4 seconds is advocated for higher speeds.  To regulate that distance or interval, note the vehicle ahead as it passes an object at the side of the road — then count the seconds that it takes you to reach the same object.  If you get to the marker before you count to 2, you need to increase your following distance.

Knowing how to judge speed, time and distance is also mandatory when merging.  If you are coming up the ramp, and a vehicle on the freeway is one-eighth of a mile away, you have approximately 7 seconds to get up to speed ahead of that vehicle.

To use this skill one must turn their head to observe traffic present on the freeway.  I often encounter drivers who look straight ahead while bullying their way blindly into traffic at the top of the ramp.  They may mistakenly believe that it is the onus of drivers already on the freeway to accommodate the merge by yielding to them.  Not so!

Readers may contact Bill Love via e-mail at