Traffic Calming History

European Beginnings
Traffic calming began in Europe in the late 1960’s in an effort to change driver behaviors to make streets safer for children, pedestrians and cyclists. Frustrated by cut-through traffic rendering their streets unsafe, residents of the Dutch city of Delft turned their street into an obstacle course for motor vehicles and a safe haven for their children. This first traffic calming solution, called “living yards”, or “Woonerven”, slowed traffic and lessened volume with the placement of tables, benches, sand boxes, and parking bays extending into the streets. Woonerven were endorsed by the government nearly a decade later in 1976. In the following years, the idea spread to other countries and regulations and laws were created to govern the dimensions and locations of the woonerf designs. By 1990, myriads of streets in countries such as Austria, Denmark, France, Germany, Israel, Japan, Sweden, and Switzerland were similarly calmed.

While effective for small low-volume streets, the woonerf designs slowed vehicles to 9 mph and were thus impractical for larger and more frequently traveled roads. The theory of employing physical measures to deter vehicle speed had already proven effective and experimentation began to conceive of similar ideas that would be less costly and more adaptable to larger streets. Two types of measures were considered in addition to Woonerven; diversions such as street closures or one-way streets and physical deterrents such as speed humps and similar traffic calming measures. Traffic calming was judged to be the most efficient and cost-effective of the three alternatives.

The first citywide traffic calming programs began in the early 1980’s when both Norway and Denmark were confronted with the problem of intercity traffic speeding through small towns. Unable to afford the exorbitant cost of building bypasses around each town, the government installed traffic calming measures such as chicanes, roundabouts, chokers, and other physical measures throughout local streets. With the installation of these measures, there was a significant reduction in speeds, fewer accidents, and better air quality. Many other cities throughout Europe followed suit with programs of their own.

Arrival in the United States
While street closures and traffic diverters were used in the Unites States in the late 1940’s and early 1950’s, the first area-wide traffic calming planning was conducted by Seattle in the early 1970’s. Seattle’s early success is in part attributable to its ability to attain funding for the project through a combination of proactive and reactive approaches to fund allocation. The first comprehensive project conducted by Seattle was the Stevens neighborhood demonstration, which tested the efficiency of traffic calming measures on a 12 square block area that was often used for cut-through routes. This early project illustrated several important factors critical for program success including testing measures before permanent implementation; assessing public support; conducting before and after studies of traffic impacts; studying the effect of solutions on traffic accidents; addressing concerns of emergency vehicles; and opting for the most conservative design to effectively meet the city’s needs.

Seattle’s revolutionary traffic calming planning was followed by the establishment of a citywide traffic management plan in Berkeley, CA in 1975. The first national study of traffic calming was conducted in the United States in 1980 and reviewed residential preferences regarding traffic, collected performance data on speed humps, and discussed legal issues.

In 1998, the Federal Highway Administration (FHWA) funded a more comprehensive traffic calming study by the Institute of Traffic Engineers (ITE) entitled Traffic Calming: State of the Practice, which reviewed residential streets and major thoroughfares, a variety of calming measures, and policy, procedural, and political challenges.

This study was recently followed in 2004 by an article published in the ITE Journal called Traffic Calming Practice Revisited. The article assessed a matured traffic calming market by reviewing traffic calming practices in 21 jurisdictions, comparing results to the initial ITE report. The updated study found a growing number of traffic calming programs across the US, less controversy regarding programs, improved receptiveness and interest in traffic calming, and greater use of comprehensive toolboxes employing a variety of physical measures.