The Science of Slowing Down
By: J. David Chapman, PhD, / July 17, 2026
When I served on the Edmond City Council, I frequently received calls from constituents with the same complaint: "People drive too fast through my neighborhood." The first solution that usually comes to mind is enforcement, more police, more tickets, bigger fines, or perhaps another speed bump.
While enforcement certainly has its place, transportation planners have learned something interesting over the past fifty years. The most effective way to slow traffic is often not enforcement at all. It is design. Simply put, streets teach us how fast to drive.
Think about the last time you drove through a historic downtown such as Edmond, Guthrie, Stillwater, or one of Oklahoma's many courthouse squares. Chances are you naturally slowed down without ever checking the speed limit. Why?
Because the street was sending you signals. Buildings stood close to the sidewalk. Cars lined the curb. Trees, storefronts, pedestrians, and frequent intersections demanded your attention. Everything about the environment communicated that this was a place for people, not simply a corridor for automobiles.
Now compare that to a wide suburban arterial with multiple travel lanes, broad shoulders, generous setbacks, and little roadside activity. Although the posted speed limit may be the same, the street feels completely different. Wide, open roads quietly invite higher speeds.
Transportation engineers generally describe traffic calming using three principles: deflection, constriction, and friction.
Deflection changes a driver's path through curves, chicanes, or roundabouts. Constriction narrows the driver's perception with curb extensions, refuge islands, or road diets. My favorite, however, is friction.
Friction has nothing to do with rough pavement. It is the visual activity surrounding the street. Brick paving, mature trees, storefront windows, on-street parking, public art, cyclists, outdoor dining, and pedestrians all encourage drivers to become more attentive. They slow down not because someone ordered them to, but because the street quietly suggested they should.
This philosophy dates back to the "living streets" of the Netherlands in the late 1960s and has evolved into what planners now call self-enforcing streets. I have always liked that phrase because it relies less on punishment and more on psychology.
Readers of my book subURBAN! may recognize this idea. Great places are rarely accidents. Whether we are designing neighborhoods, revitalizing downtowns, or creating successful commercial districts, good design quietly influences human behavior.
Perhaps the biggest lesson is this: we often try to solve speeding with enforcement when the real solution is geometry. If a street feels like a highway, people will drive like they are on a highway. If it feels like a neighborhood, they will usually act like they are in one.
Sometimes the best way to slow traffic isn't to tell people to slow down. It is to build a street that quietly asks them to.
Dr. J. David Chapman is Chair of Finance & Professor of Real Estate at The University of Central Oklahoma (jchapman7@uco.edu)