The role of street and area lighting has gone through significant change over the years. In the early 1900s only about 10% of the population lived in urban areas. Today that number is over 50%. The introduction of gaslight street “systems” (i.e. luminaires and a distributed fuel source) in the early nineteenth century was universal in urban areas within a generation and greatly altered the lives and schedules of city dwellers. By the 1870s, the emerging electrical corporations were constructing metropolitan electric generation equipment to provide a dependable power source and open the way for electric light to supplant gas light in homes, the workplace and on public thoroughfares. At expositions and fairs in the early 1990s, these same industries showcased their revolutionary electric appliances and indoor and outdoor lighting to an eager American public.
Born out of these expositions, movements such as the City Beautiful Project and White Ways led to widespread municipal installations of incandescent electric lamps in ornamental post type luminaires in parks, streets, train stations and around libraries and government buildings; such installations were seen as signs of public pride, progress and prosperity. The primary goal of street and area lighting was to create illumination that provided a safe, attractive and well lit environment for the people who lived and moved about the neighborhoods.
The emphasis on lighting for automobile roadways and as a security measure began to develop just after World War I. New lighting industry codes were published that encouraged municipalities to install a new type of bracketed luminaire, much higher than those in the business district, that held the lamp out over the street and illuminated the pavement so that drivers could see farther ahead and distinguish obstacles at a distance. At the 1939 New York World’s Fair, General Motors displayed their vision for American cities connected by a network of four-lane high speed highways. Designers responded with a variety of new streamlined streetlight luminaires, based primarily on a 20-foot steel, concrete or cast iron pole and a single bracket and a simple bracket and lamp. 1
Responding to the massive road building projects following World War II, the industry advocated the need for specialized roadway luminaires, increased luminaire density and most importantly, higher light levels. A new lighting technology, sodium vapor, was promoted as the ideal efficient alternative to traditional incandescent lamps. With more highways under construction, tighter municipal budgets, and urban neighborhoods being transected by primary roadways, it was only a matter of time before the orange glow of sodium vapor, and later, the bluish glow of mercury lighting began showing up in city and neighborhoods.
The relighting of American cities and towns with high pressure sodium continued at record pace into the 1960s. By the 1970s, lighting professionals, the scientific and medical research communities and municipal planners and engineers began to address the issue of “light pollution.” “Was all this light,” they asked, “actually contributing, through psychological and other factors, to the problems it was supposed to address? Can we lower the number of outdoor luminaires and the overall illuminance levels and still create nighttime environments that instill feelings of safety and enjoyment?”
Today, the discussion is as much about the quality as it is about the quantity of lighting for streets, urban areas and roadways. State and Municipal authorities are faced with creating lighting schemes for a diverse urban landscape, while taking a responsible approach to minimize the level of light pollution impacting on our night environment. Government agencies and industry organizations increasingly emphasize the importance of environmentally responsible and sustainable building practices, including the use of innovative lighting solutions that not only reduce energy and maintenance costs, but reduce their carbon footprint.
In the mid 1900’s one of the primary goals of lighting was to help reduce the incidence of road accident, improve traffic flow and provide visual comfort for vehicle operators. By the early 1970s, high intensity light, in particular high pressure sodium vapor had become the pervading source of illumination in American cities, due to its high levels of illumination and long, reliable lifespan. Even with its benefits, the unattractive yellow-orange color made it difficult to distinguish colors in the area being illuminated. The unnatural orange tint of urban streets at night is something city dwellers had gotten used to through necessity rather than choice.
Beginning in the 1990s, city planners and architects began to question whether the over-use and misapplication of high-intensity roadway light sources was the best choice for city streets, parks, historic buildings and urban area lighting. Lighting designers pointed out that a footpath and a roadway, for example, with their differing surfaces, called for radically different lighting solutions, providing visual comfort and aesthetic sensitivity. At the beginning of the 20th century, incandescent street lighting was the preferred light source because of its sparkle, its white light and ability to render surroundings in truer colors. Advocates of the City Beautiful movement rejected efforts to explore more efficient, economical discharge light sources because “lighting must be made agreeable to the eye.”
Today, outdoor lighting applications are no longer confined to yellow light sources. Recent technological advances in metal halide, LED and fluorescent technologies are providing new alternatives that combine the qualities of daylight with the energy efficiency of high-pressure sodium lamps. This alternative is white light. As cities continue to grow and develop a marketable identity, the use of white light sources is becoming a key contributor in improving streets, public spaces and public life, creating a more livable community that residents are proud of and can relate to.
White light in urban residential and business settings offers many clear benefits when compared to yellow light:
Today’s advanced white light sources have equal or better energy efficiency than high pressure sodium.
Brighter perceived ambience, greater visibility and energy efficiency.
Improved color characteristics and color rendering. Colors appear more natural to the eye.
At the recommended illuminance levels for urban lighting, lower wattage alternatives can be use; they provide acceptable illuminance levels and lower energy consumption.
White light sources are perceived as brighter than yellow light at lowlight levels; it becomes possible to reduce overall light output while still giving users what they expect from the light source. UK lighting standards for exterior lighting now allow the minimum level of illumination on secondary roads and pedestrian walkways to be reduced as much as 30% (depending on the application) when the white light source used has a color rendering index of >60. or greater. 1
Increased visibility for motorists and pedestrians. White light improves drivers’ ability to see objects and roadside movement at a greater distance, i.e. a wider margin of safety.
White light helps people feel safer when moving around outdoors at night. Superior CRI, higher perceived brightness, makes it easier to distinguish objects, colors, people and facial recognition at a distance.
By the year 2050, more than 75 percent of the world’s population will live in cities. Faced with this unprecedented growth in our urban areas, and the associated growth in vehicular traffic volume, lighting will play an increasing role in providing enhanced levels of safety and pride in our streets, roadways and downtown areas.
Around the world, legislative imperatives are furthering the move towards “sustainable cities” where innovative urban lighting solutions not only reduce energy and maintenance costs but also their carbon footprint. Forward-thinking urban planners, architects and engineers must introduce new lighting solutions into their future designs that provide sufficient lighting quality for a diverse urban environment while consuming less energy. These advanced light sources will replace many of the inefficient light sources that have been in use for many years and which, over time, will be gradually phased out.
In this time of financial constraint and energy challenges, LEDVANCE gives state and local officials the tools to improve the quality of life on our roads, streets and in our cities and achieve more sustainable cities by lowering energy consumption and reducing CO2 emissions. We offer a wide range of advanced energy-saving halogen, high-intensity discharge, fluorescent, inductive and LED light sources as well as cutting-edge ballasts, power supplies, and intelligent lighting controls. New white light options like SYLVANIA METALARC POWERBALL and LED street lighting systems, reduce operating costs and TOC while providing superior light quality. Whether you’re lighting an historic building, tourist landmark, facade, bridge, fountain, park, street or roadway, our sales, and engineering professionals will work with you to specify solutions that suit your requirements and your budget.
Lighting has a significant impact on how people feel about the urban or suburban areas in which they live, work or enjoy recreation and entertainment. As a result, the illumination of our roadways, streets and outdoor areas has evolved from a simply functional design approach and now poses the same demands and disciplines as designing a successful interior lighting scheme.
Outdoor lighting differs from interior lighting in that there is no physical structure to contain the light or redistribute it. As a result, the designer has to make many judgments determining the need for light in the first place, the level of illuminance that will be appropriate and how to apply it in regards to the outdoor environment. Otherwise energy will be wasted and light pollution and light trespass may occur. Illuminance levels will differ greatly between parking lots and garages, pedestrian walkways, roadways, residential streets and parks or common areas. Studies of the intended use of an area, the type and schedule of activities taking place, and the finite limits of the area will help control energy use, and unnecessary equipment and maintenance costs.
The functional characteristics of the luminaires (e.g. optical control, maintenance requirements, physical appearance, installation and mounting heights) must be appropriate to the application. Luminaires also play an important architectural role, in that during the day they become an integral part of the urban scene.
Lighting controls can save significant amounts of electricity and avoid light pollution. Programmed shutdown or dimming of luminaires at specific curfews is effective. Motion sensors may be appropriate in areas where late hour activity is limited.
In addition to providing adequate illuminance levels, the lighting must be pleasing and inviting. It should promote a sense of well-being, encourage social interaction and complement urban night life. Color temperature and color rendering characteristics of light sources affect the visual aesthetics and attraction of outdoor spaces. Lamps with CRIs of 80 or above, help people identify and distinguish colors and movement at a distance. It is this quality of light that can help to indirectly deter criminal activity.