Streets for People - A Radnor Coalition
Traffic-Calming Terms

bicycle lane - a separate lane painted on the road to alert drivers to cyclists.

bollard - a thick, heavy concrete or metal post set into the street or sidewalk to warn or restrict motorists.

chicane - (from chicanery, or trickery; originally the alternating obstacles on automobile race courses that forced racecars to slalom) barriers built into the street using high curbs, plantings, trees or bollards; they can include bike lanes. Chicanes make drivers zigzag slowly and carefully. You can create instant chicanes by parking on your street, optimally diagonally from other parked cars. This will slow traffic dramatically.

curb extension - sidewalks that project into traffic intersections to slow turning drivers and protect crossing pedestrians.

diagonal parking - on wide streets (the 100 blocks of Bloomingdale and South Wayne Avenues, for example), diagonal parking narrows the roadway, forcing drivers to slow down and pay attention. Often the parking lane is a different color to further emphasis the narrowness of the street. As a bonus, it can produce 40% more spaces than parallel parking.

inset lights (also known as inroad lights) - flashing lights set into the roadway to warn drivers about pedestrians. Bryn Mawr, PA, has these lights on its Lancaster Avenue crosswalks, to great effect. Inset lights can be triggered by a push button or pressure-sensitive mats.

median - a raised island dividing the two lanes of vehicular traffic. The wooded boulevards of Paris are the most influential example. Because medians make the road look narrower, drivers slow down. The 100 block of North Wayne Avenue would be a perfect median site.

pinch point - a narrowed section of street sometimes just one lane that forces drivers to reduce speed. Pinch points can be created by curb extensions, bollards or medians, and accented with landscaping. They are particularly appropriate on long avenues where drivers accelerate mid-block.

raised crosswalk/intersection - a high-tech speed hump, raised crosswalks alert drivers to pedestrians. They are even more effective when combined with curb extensions and contrasting paving.

roundabout - a traffic circle, often highlighted with landscaping, signage and/or bollards, that motorists must circle in a counterclockwise direction. Unlike traffic lights or stop signs, a roundabout forces every driver to slow down.

signal progression - timing traffic lights so that cars moving at the posted speed limit will hit green; faster cars are forced to brake. Signal progression is particularly important on Lancaster Avenue to move large volumes of cars and trucks through central Wayne in a controlled and direct fashion.

speed limits - often the first line of attack against speeding motorists. Even small changes in speed make an enormous impact: 5% of people die when struck by a vehicle going 15 mph, but 85% die at 40 mph. While posted speed limits have some impact, they are most effective when combined with structural changes to the roadway that force even the most resistant drivers to slow down.


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