"In almost all U.S. cities, the bulk of the right-of-way is given to the roadway for vehicles, the least to the sidewalk for pedestrians... just suppose that Americans were to extend their walking radius by only a few hundred feet. The result could be an emancipation... --William H. Whyte (CITY: Rediscovering the Center)
Developed in Europe, traffic calming (a direct translation of the German "vekehrsberuhigung") is a system of design and management strategies that aim to balance traffic on streets with other uses. It is founded on the idea that streets should help create and preserve a sense of place, that their purpose is for people to walk, stroll, look, gaze, meet, play, shop and even work alongside cars - but not dominated by them. The tools of traffic calming take a different approach from treating the street only as a conduit for vehicles passing through at the greatest possible speed. They include techniques designed to lessen the impact of motor vehicle traffic by slowing it down, or literally "calming" it. This helps build human-scale places and an environment friendly to people on foot.
Besides its power to improve the livability of a place, the beauty of traffic calming is that it can be applied inexpensively and flexibly. The strategies outlined below in The Traffic Calming Toolbox can be employed by painting lines, colors and patterns; using planters, bollards and other removable barriers; eliminating or adding parking; or installing sidewalk extensions or similar structures with temporary materials. All provide an opportunity to test devices, combinations and locations, fine-tuning the approach according to results. Traffic calming, along with other small-scale improvements, can enhance a place immediately, while being tested and refined to meet long-term needs. When funds are available, the right combination of devices can be transformed into permanent improvements and extended over a broader area. Regardless of what traffic-calming action is undertaken, the benefit to a community is greater when the technical improvements are strengthened by visual enhancements like trees, flowers and other amenities.
Cars park diagonally, jutting out from the curb, rather than parallel to it. The benefits:
Single or double traffic lanes, either face-to-face or with a median, sometimes flanked by parking. The benefits:
These techniques provide a flexible way to take back space from the street for non-motor-vehicle uses. Traditional traffic engineering calls for 12- to 13-foot lanes, citing "traffic safety" standards - but newer evidence shows that lanes as narrow as nine feet can still be safe for driving.
Interchangeable terms for sidewalk extensions in selected areas - such as at intersections or at mid-block - as opposed to a full sidewalk widening. The benefits:
Sidewalk extensions that jog from one side of a street to the other to replicate such a circuitous route. The benefits:
Large, raised, circular islands at the middle of major intersections, around which all oncoming vehicles must travel until reaching their destination street, where they then turn off. The benefits:
Essentially "mini-roundabouts" designed for small intersections, often used to slow traffic from a wide street into a smaller local street. Traffic circles:
Elevated islands parallel to traffic lanes down the middle of the street, as on a boulevard. The benefits:
The longer the radius of a curve, the faster a vehicle can move around that curve - as many pedestrian witness when, in crossing at an intersection, they are confronted by a car whizzing around the corner seemingly out of nowhere. Reducing a corner radius to somewhere between one and twenty feet can:
These physical barriers redirect traffic heading for a certain street onto a different course, reducing vehicle overload on vulnerable (usually residential) streets overrun by through traffic looking for shortcuts.
These devices reduce speed by introducing modest up-and-down changes in the level of the street, thereby requiring drivers to decelerate.
The "starter set" of traffic-calming tools outlined above can be effective in a variety of ways. However, each tool has its own specific applications, and not every one fits every single circumstance. Some tools are more effective if used in combination with each other, or with alternative transportation approaches like bicycles, buses or light rail. The right use hinges on existing conditions along a street and the desired outcomes. The following is a sampler of issues that need to be considered when making traffic calming choices.
Transit can be an efficient, more economical and less polluting alternative to the automobile - but transit alone doesn't necessarily make a place more livable. People still need to cross streets safely to reach a train station, bus stop, or other transit hub. And they need a pleasant and direct walking route along the way. This is where traffic calming comes in.
Traffic calming measures can make the trip to the transit station more walkable and convenient, while providing space for amenities to make the trip more pleasant. Although traffic calming and transit seem to be natural partners, sometimes their goals can conflict. When a traffic-calming strategy performs its job well, it may interfere with the efficient movement of a transit vehicle, or even its comfort, as when speed humps create a bumpy ride on buses. Certain strategies can maintain the benefits of traffic calming while allowing transit to function effectively:
Cushions enable buses to pass smoothly over an area, yet still slow smaller vehicles. Bus "bumpouts" or "nubs" allow buses to pick up passengers without having to move out of the traffic lane. They extend across a parking lane to meet the traffic lane (and the bus that is in it), giving passengers a safe and accessible approach, while also saving travel time. Nubs can be built to line up with both the front and rear doors of a standard bus, and can accommodate amenities like bus shelters, benches, telephones and waste receptacles.
By and large though, as long as they are coordinated to meet the needs of a specific street environment and its surrounding community, traffic calming and transit can work together to provide the comfortable, convenient and safe connections that enhance a place and promote a positive experience there. Two considerations to make are: How does transit relate to sites where where traffic-calming improvements are needed? How can transit and traffic calming reinforce one another in order to help people get from place to place without driving?
Transportation agencies often believe they could be sued by drivers (not pedestrians) who might have a collision if design standards that give cars unencumbered, speedy passage are not followed. However, the most serious (and fatal) collisions are caused by high speeds. Traffic calming creates a set of checks and balances that compel those at the wheel to drive slowly and carefully, making streets safer for both drivers and pedestrians.
In practice, liability is a murky area, subject to interpretations that can conflict from one jurisdiction to another. In New Jersey, for example, the Borough of Belmar was sued by Monmouth County for trying to make a street safer to cross. The street, Belmar's Ocean Avenue, is usually clogged with vehicles that rarely abide the 25 mph speed limit. Throngs of summer tourists cross Ocean Avenue to get to the beach, and on average, there is a fatal pedestrian/vehicular accident every two years - a rate that prompted the Mayor and his borough to take action.