Safety is the essential advantage of lighting. By illuminating roads, parks and other public spaces, we reduce the risks of accidents and injuries. Lighting is especially important for driving in the night. Whether driving on the motorway or in residential areas, good lighting improves visibility and minimises the risk of accidents. With a growing number of people in urban areas opting for sustainable modes of transportation, cycling has become extremely popular. It is an added necessity to ensure that we are able to ensure the safety of cyclists. Well-lit public spaces also provide pedestrians the much needed sense of security to step out after sundown.
Importance of Street Lighting
In any area street lighting has an important role to play in:-
- Reducing risks of night time accidents;
- Discouraging crime;
- Assistance in the protection of buildings/property;
- Making a secure environment for habitation;
- Discouraging vandalism
In designing lighting within streets, consideration should be given to the type of lighting that is efficient in the context of the street. It is often the case that lighting in streets is essentially suitable for highway lighting but is not entirely in context with the street character/environment. Key issues in the provision of lighting are scale, colour and luminance which are as described below:
- Scale: As said above, mostly the street lighting is actually provided for highway/expressway purposes. An outcome of this is that it is often located at such a height unsuitable to the cross-section of the street and out of scale to the pedestrian/cyclists. Urban Design consideration should be taken in street design for the purpose of pure lighting, the scale of lighting relative to users of the street and the messages/signals sent to the drivers by lighting design. Picture showing efficient use of lighting w.r.t height, color and luminance to enhance the urban design with a Combination of Street lights and pedestrian lamp posts
- Color: The color of lighting is another important consideration. Where pedestrians are concerned like in small streets, white light is preferable, rather than yellow or orange. White lighting allows better judgment of street features/elements, including the facial expressions of the street users, which can be an important component in revive personal security concerns.
- Luminance : An acceptable level of street lighting is 5 lux as per the Bureau of Indian Standards, although it is recommended that at locations where people gather, for example bus stops, meeting spaces (in rural areas), 10 lux is appropriate. In providing better urban design and inclusive streetscape, the flow of lighting levels is very important, with sudden changes in lighting level being extremely problematic for partially sighted humans/people. The shading effect of trees/shrubs should also be considered in determining the species, its location and management.
- Other Lighting Consideration : In some contexts, lighting can contribute to the actual sense of place of a street/road with both active and passive (reflective) lighting features blurring the difference between functional and aesthetic contribution to the streetscape. These initiatives are often based around community projects and are practiced in various locations of Gujarat, India. A prominent example of this approach has been demonstrated by Government of Gujarat, India as part of their Green Highway and Boulevard project which has focused on green vision, street/highway quality and its management.
Types of Street Lights –
There are mainly six types of street lights available which can be used at various locations in conjunction with Urban Design of the area and other factors of street lighting. The types of street lights are as follows:
1. Metal Halide Street Lights :
Metal halide lamps/bulbs are mainly used in streetlights, parking lot lights, and stadium lights. They are very bright in color and contribute to a lot of light pollution. They are fairly efficient. They produce very white light and have good color performance/rendering, meaning that objects under these lights look their true color.’
Metal Halide Street Lights
2. High Pressure Sodium (HPS) Street Lights :
The high pressure sodium lamp (HPS) is the most commonly used street light in many countries throughout the world. It produces bright light by electricity via mixture of gases, which produces light. The lamp itself is much preferable because it requires very little/less maintenance. These lamps are fairly efficient. They take few minutes to turn on completely and produce a yellow-orange kind of glow.
Low Pressure Sodium (LPS) Street Lights
3. Low Pressure Sodium (LPS) Street Lights :
The low pressure sodium (LPS) lamp also works like the HPS light. Instead of producing pure white light (all the seven colors of the rainbow), LPS lamps produce exclusively yellow/warm yellow light. While this light is very efficient, it takes few minutes for the bulb to turn on completely. The light is very yellow-orange in color.
4. Light Emitting Diode (LED) Street Lights :
Light Emitting Diode (LED) Street Lights
LED technologies have developed rapidly in the last 5-6 years and now these bulbs are also being integrated into outdoor lighting solutions. While the energy savings are significant, LEDs emits a lot of blue/white blue light, excess of which can have negative effects on human health and wildlife. In combination with solar panels these lights can drastically minimize the demand of electricity requirements.
5. Phosphor-Converted Amber (PCA) LED Street Lights :
PCA LEDs have only been on the market for the past 2-3 years. They use very less energy and have good color representation, but are still rather expensive. Few Indian cities like Bombay have already installed these lights on their streets.
6. Narrow-Band Amber (NBA) LED Street Lights :
Narrow-Band Amber (NBA) LED Street lights are a brand new technology. Rather than emitting pure white light (all the seven colors of the rainbow) and blue light, they emit mostly in the yellow/ warm yellow color. They still have good color representation, meaning that they do not make objects look grey like LPS lamps can do. Because this technology is very much new, these bulbs are not commonly available and as such, and are still expensive. Overall they are very efficient.