Walking across a busy, unsignalized intersection is a dangerous and risky exercise in many municipalities. Speed limits are often ignored as many roadways are wide and straight with little to discourage faster speeds. Roadways that are motor vehicle-oriented by their nature often do not encourage active, healthy living. Designed for vehicle traffic, streets may be too fast, too wide, or otherwise too dangerous to accommodate bike and pedestrian traffic. Traffic calming offers a solution that can make streets safer and more enjoyable for those walking and biking. Traffic calming is defined by the Institute of Traffic Engineers (ITE) as “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.” These measures are not meant to disrupt the flow of motorized traffic but to change driver behavior, increasing safety for all. These measures can also help promote walking and bicycling, improve streetscape aesthetics, reduce crime and increase property values.
The goals of traffic calming include:
The speed of motor vehicles influences both the likelihood that a crash will occur and the severity of crashes. In general, slowing cars down by just one mph will result in a five percent reduction in the number of crashes. The degree of injury due to crashes is very sensitive to impact speed. Even a small reduction in speed can affect whether a crash is fatal, serious or slight. This correlation between speed and injury is especially important for pedestrians and cyclists. A pedestrian struck by a vehicle moving 20 mph has a 95 percent chance of survival. At 30 mph that chance has dropped to 55 percent. For the unfortunate walker or biker struck at 40 mph, there is only a 15 percent chance of survival. Nearly 90 percent of pedestrians who survive being struck by a car traveling a 30 mph speed limit will sustain serious injuries.
Both political and community support are critical to the success of these physical measures. Public participation is important at all stages, from initial assessment and design concept to evaluation of implemented strategies. Ongoing evaluation is necessary to address any changes in response to community needs. Local police involvement is also crucial; police can provide traffic reports and accident data validating the need for proposed measures. First responders should review plans to ensure that proposed changes will not impede emergency response vehicles.
Traffic calming measures can be thought of as a diet for the street. Just as increased walking and biking improves the health of residents, the health of the physical environment can also be improved. Streets that have been widened to accommodate larger, heavier and faster streams of motorized traffic often lead to decreased pedestrian safety and a lower level of livability. By implementing a “road diet,” streets become leaner, safer, and more productive. A road diet reduces the number of lanes, reallocating the space for sidewalks, bike lanes, and/or on-street parking. Reducing the number of motor vehicle lanes compels drivers to abide by the speed limit, increasing safety for drivers, bikers, and pedestrians. Most road diets result in minimally decreased vehicle capacity. Lane reduction may also increase the use of alternate modes of transportation. Adding bike lanes and pedestrian sidewalks and pathways encourages people to get out of their cars. Putting people on the street can increase the safety of an area and provide potential customers to area businesses.
The Project for Public Spaces has put together a toolkit to guide communities when deciding upon traffic calming measures. The organization stresses the flexibility inherent in the process. Inexpensive measures can be implemented immediately and monitored while long-term strategies are developed. Measures profiled in the toolkit are:
Chicanes narrow the road and disrupt the view ahead. Chicanes require slow and careful driving. Larger vehicles are able to navigate roadways with chicanes. The curb extensions can be created in a number of ways, making chicanes a feasible measure that can be modified later as needs change. Sculpture and plantings can be added to enhance the streetscape.
Parallel or diagonal parking that alternates street sides can also be used. Parking bays can be created by simply repainting the roadway or by installing raised, landscaped islands at the ends of each bay. When the extensions are placed directly opposite one another, a “choker” is formed. Chokers, also called “bulbs” and “neckdowns,” are often located mid-block and may contain a pedestrian crosswalk. The crossing distance is shortened and pedestrians are given a safe place to stand while waiting to cross.
There are several issues a community should address when evaluating the various measures. The types of vehicles (buses, emergency vehicles, etc.) using the roadways need to be identified. The surrounding land uses, activities, and users need to be accounted for. Both existing and planned uses and activities must be considered. Ideal traffic speeds should be determined. Options for transit service also must be evaluated. Environmental issues, such as drainage needs, must also be considered in the planning stage. Holding public meetings and conducting walkabouts (or “walking audits” – see p. 15) of the area can be valuable in identifying both needs and potential solutions. If the expertise does not exist locally, a planning consulting firm can help develop designs for the physical improvements. These designs should reflect community recommendations and can be modified through the public participation process.
Communities should also consult the traffic calming guidelines set forth by the New Jersey Department of Transportation (NJDOT). The Roadway Design Manual presents current Department guidelines pertaining to roadway design on the State Highway system. NJDOT is currently in the process of updating the Manual to include traffic calming measures. Although traffic calming infrastructure is not always appropriate for much of the state highway system, many exceptions exist especially when a state road serves as a local “Main Street” or the roadway speed is 35 mph or less due to residential or business land use. The pending traffic calming section will include design guidelines for speed tables, raised intersections and crosswalks, roundabouts, curb extensions, gateway treatments, bicycle lanes, colored and textured pavement and intersection median islands to name a few.
In addition, the NJDOT’s NJ Future in Transportation (NJFIT) program has produced a toolbox, available online, with tools and techniques for improving local traffic conditions. The toolbox contains sections on both traffic-calming measures and context sensitive design. The ITE web site is also a valuable resource, with a searchable collection of articles, case studies, selected reports, photographs of specific measures, and links to related organizations and municipalities that have implemented traffic calming.
