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Porphyry and Curbless Streets – Part 1

This first in a series of three blogs about paved streets, public spaces and sidewalks where the street design incorporates curbless streets.  This discussion explores the concept first created in the Netherlands, a woonerf.  Porphyry and other stone pavers figure prominently in these designs.

So what is a woonerf exactly? Picture a regular street, but narrow, minus a curb, finished with pavers instead of asphalt. Developed by Dutch traffic engineer Hans Monderman, a woonerf is a street where pedestrians and cyclists have legal priority over motorists as implemented in the Netherlands and in Flanders. Techniques include shared space, traffic calming and low speeds. This concept goes by a number of other names, such as Living Streets and Complete Streets in the USA, and Home Zones in the UK.

Porphyry pavers in Woonerf

Woonerf History

In the late 1960’s in the city of Delft, The Netherlands, motor vehicle dominance led to a revolt against the automobile by angry residents. Completely fed up with the negative impacts of cars on their street and the lack of a remedy by the city, a group of residents tore up the brick pavement one night so that cars had to maneuver in a serpentine pattern at much slower speeds. The initiative did not close or even partially close the street, but forced drivers to behave differently, i.e., slower. Necessity is the mother of invention and consequently the woonerf, “living yard,” was invented. Later in 1972, the first officially sanctioned woonerf was built in Delft. This is commonly considered to be the birth of modern traffic calming.

In 1976, the Dutch Parliament passed legislation permitting the installation of woonerven (plural) and by 1983; more than 2,700 had been constructed. Surveys indicated that the majority of the population considered the woonerven attractive. They also reduced the number of injury-related collisions by 50 percent. The lower speeds also contributed to a decline in the severity of the crash-related injuries.

The woonerf concept was later replicated in Germany and termed Verkhrsberuhigung, or “traffic tranquilization,” later called traffic calming in English. Traffic calming in Germany became a widely accepted and successful transportation practice. The Germans then developed 30 kilometers/hour (19 mph) streets, which greatly reduced the cost of traffic calming when compared to the relatively expensive woonerven although without the aesthetics.

Traffic calming rapidly spread through Europe, Australia, New  Zealand, Japan, and most of the developed world. It has also been used in the United States and Canada. It was originally initiated through the efforts of community associations in the northwest United States, but is now a transportation practice used by a rapidly growing number of cities and towns throughout the country. The first generation of traffic calming programs was developed by Portland, Oregon, and Seattle, Washington, and later became the model for many cities, including the initial policy for West Palm Beach.

 

The Following is an excerpt from a United States Federal Highway Administration Course:

 

Federal Highway

Administration

University Course on

Bicycle and Pedestrian Transportation

 

“The Woonerf

A woonerf  (Dutch for “living yard”) combines many of the traffic–calming devices just discussed to create a street where pedestrians have priority, and the line between motor–vehicle space and pedestrian (or living) space is deliberately blurred. The street is designed so motorists are forced to slow down and exercise caution. Drivers, the Dutch say, do not obey speed limit signs, but they do respect the design of the street.

Woonerf Design DrawingThe woonerf (plural—woonerven) is a concept that emerged in the 1970’s as planners gave increased emphasis to residential neighborhoods. People recognized that many residential streets were unsafe and unattractive and that the streets, which took up a considerable amount of land area, were used for nothing but motor vehicle access and parking. Most of the time, the streets were empty, creating a no–man’s–land separating the homes from one another.

The Dutch, in particular, experimented extensively with street design concepts in which there was no segregation between motorized and non motorized traffic and in which pedestrians had priority.

A law passed in 1976 provided 14 strict design rules for woonerven and resulted in the construction of 2,700 such features in the following 7 years.

The woonerven were closely evaluated, with the following findings:

  • Injury crashes were reduced by 50 percent.
  • Vehicle speeds were reduced to an average of 13 to 25 km/h (8 to 15 mi/h).
  • Nationally, 70 percent of the Dutch population thought woonerven to be attractive or highly attractive.
  • Non motorized users assessed woonerven more positively than motorized users.
  • Feedback from residents living on woonerven was very positive. They appreciated the low traffic volumes and absence of cut–through traffic, but considered the larger play areas and other improvements to the street environment to be even more important benefits.”

The next blog in this series will focus on designs of curbless streets in commercial areas.

Porphyry’s composition determines its high compression strength, resistance to stains, slip resistance, and high freeze/thaw ratings.  The stone is the most popular paver in Europe, and is favored for its flexibility in design, beauty, durability and low maintenance requirements. ADA Compliant Porphyry pavers are also adaptable to a permeable paving set. The stone is by far one of the most durable pavers in the world.  These beautiful materials are available from Milestone Imports.   Milestone supports the creativity of architects, planners and designers. Porphyry offers surfaces of various finishes and mixed colorings, tending towards tones of grey, gold, violet and red, depending on where it is extracted.  The products are available in North America from Milestone Imports.  –  www.milestoneimports.com