ITE traffic calming definition

Institute of Transportation Engineers. ITE Journal, Jul 1997 by Lockwood, Ian M

A SUBCOMMITTEE ESTABLISHED TO DEFINE TRAFFIC CALMING PRESENTED A DEFINITION AND AN INTENDED INTERPRETATION OF THE DEFINITION IN MARCH AT THE 1997 INTERNATIONAL ITE CONFERENCE.

IN SEPTEMBER 1996, AT THE 66th ITE Annual Meeting in Minneapolis, Minnesota, there was a special meeting to discuss traffic calming. About 40 people from countries around the world attended. The purpose was to discuss how the ITE could contribute to, or be involved with, traffic calming. During the discussions, it became apparent that people had different definitions of traffic calming. Progress was difficult due to the lack of a common definition. A subcommittee established to define traffic calming for ITE presented its findings in March at the 1997 International ITE Conference in Tampa, Florida, USA.

A SAMPLE OF VARIOUS DEFINITIONS

Research into the definition of traffic calming confirmed that a common definition did not exist and that the range of definitions was broad. For example, Tim Pharoah and John Russell defined traffic calming as "the attempt to achieve calm, safe and environmentally improved conditions on streets."l Dr. Carmen Hass-Klau stated that the Pharoah/Russell definition did not go far enough.2 She felt that in the narrow sense, traffic calming meant "to lower speeds." Then, in a broader sense, she felt that it must be thought of as "an overall transportation policy concept" to promote non-automobile modes of transportation. Her definition included such things as road pricing, taxation changes and parking restrictions. Her definition was, "the combination of policies intended to alleviate the adverse environmental, safety and severance effects motor vehicles continue to impose on both the individual and society at large." Another definition of traffic calming developed by a British group of engineers and surveyors was, "the application of traffic engineering and other physical measures designed to control traffic speeds and encourage driving behavior appropriate to the environment." 3

THE PROBLEM

The sample of definitions indicated that traffic calming could mean anything from lowering motor vehicle speeds to an all-encompassing transportation policy. Unfortunately, many definitions for the same term lead to communication problems-orally or in written legislation and guidelines. For example, how is ITE supposed to develop a set of traffic calming guidelines for its membership when its membership has widely varying views about what traffic calming is? How can a municipality support traffic calming without adopting its own definition? To help the public, transportation professionals, municipal staff and politicians communicate effectively about traffic calming, a common understanding of the term is necessary.

THE DEFINITION

Traffic calming is the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users.

INTERPRETATION OF THE DEFINITION

The research into the definitions of traffic calming showed that, with few exceptions, the definitions were accompanied by interpretations to ensure a clear understanding of the intent. For example, the Ontario Traffic Conference's definition of traffic calming was very good but extremely long.4 Its length made it very easy to interpret, and parts of it were used to help interpret the draft ITE definition. The interpretation is not only important to define what traffic calming is, it also determines what traffic calming is not. That is, if something is not included in the interpretation, then it is likely not traffic calming. For further guidance on what traffic calming is not, see the section entitled "Related Words and Phrases."

The definition's phrase "mainly physical measures" means physical measures and a supportive environment, which includes such things as policy and legislative support for traffic calming and flexibility of standards, guidelines and practices. A supportive environment is as important as the traffic calming measures themselves because it is what allows traffic calming to happen. The phrase "reduce the negative effects of motor vehicle use" means changing the design and the role of the street to reduce the negative social and environmental effects of motor vehicles on individuals (e.g., speeding, intrusion, etc.) and on society in general (e.g., energy consumption, pollution, urban sprawl, etc). The phrase "alter driver behavior" addresses the self enforcement aspect of traffic calming; the lowering of speeds, the reduction of aggressive driving and the increase in respect for non-motorized users of the streets. The phrase "improve conditions for non-motorized street users" means to promote walking and cycling, increase safety, create a feeling of safety, improve the aesthetics, etc.

The categories of traffic calming measures include: vertical changes in the street (e.g., speed humps, speed tables, raised intersections), lateral changes in the street (e.g., chicanes, offset intersections, lateral shifts), constrictions (e.g., narrowings, pinch points, islands), narrow pavement widths (e.g., medians, edge treatments), entrance features, traffic circles, small corner radii and related streetscaping (e.g., surface textures and colors, landscaping, street trees and furniture). This list of measures is particularly useful because it gives the categories of traffic calming measures, while not limiting the ability to create new measures within those categories.