Types of Traffic Calming Methods

Speed Bumps, Humps & Tables

All in the same family, they raise the pavement three to four inches. Although the terms are popularly used interchangeably, engineers refer to speed "bumps" as narrow and abrupt, best confined to parking lots. Speed humps and speed tables are more gradual, often 22 feet start-to-finish, usually with a flat top.
PRO: Comparatively inexpensive; effective in cutting down speed; self-enforcing; make drivers think about their roadway.
CON: Noisy, aggravating, and tough on emergency vehicles.

Traffic Circles

In residential areas, may be as small as 16 to 25 feet in diameter; just enough to cause motorists to slow and alter their path. Rotaries are larger versions used at major intersections.
PRO: Can be attractively landscaped and keep traffic flowing.
CON: May confuse motorists and make pedestrian crossing more difficult. Bicyclists sometimes find them difficult to negotiate.

Chicanes, Bends or Deviations

Roadway redesigns that make motorists drive around fixed objects, usually curbs extending alternately from opposite sides to form a serpentine pathway.
PRO: Visually pleasing, better for emergency vehicles.
CON: Expensive.

Neckdowns, Chokers, Bulbs

Various forms of narrowing the road at mid-road or intersections, usually by protruding sidewalks into the street from one or more sides.
PRO: Can be aesthetically pleasing; help pedestrians cross.
CON: Can be a problem for bicycles, snow removal.

Narrow Roads

Using sidewalks, landscaping or striping to narrow lanes to about 10 feet.
PRO: Drivers instinctively slow; pedestrian-friendly; creates neighborly scene.
CON: Can be tough on bicyclists; eliminates on-street parking.

Raised Intersections, Changes in Road Texture

Can use grooved asphalt, colored paving stones, brick, or for the ultimate effectiveness, cobblestones.
PRO: Gets drivers' attention; good for pedestrians.
CON: Noisy for neighbors; can be bumpy for bicyclists.

Direction Changes

Accomplished by "diverters" that diagonally bisect an intersection, traffic barriers that force cars to turn one direction, sidewalk "bulbs" that block access to one lane. All force drivers out of straight-line routes.
PRO: Effective in stopping short-cut and cut-through traffic.
CON: Can be costly, confusing to visitors, and add to commutes and emergency response times.