Gulf’s infrastructure projects put lighting under the spotlight

Lighting enables us to see when there is not enough natural light. Nowhere is this more important than on the roads. With so many road projects underway in the region, road lighting is something that is coming under the spotlight. CW finds out how the more sophisticated systems can help improve road safety and reduce maintenance costs.

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By  Colin Foreman Published  April 23, 2005

Gulf’s infrastructure projects put lighting under the spotlight|~|AUTOROUTE body.jpg|~||~|The rapidly growing populations around the Gulf are fuelling much of the construction activity we have grown accustomed to seeing everyday. One sector where this is particularly true is new road projects, as the number of people travelling around the region’s cities increases on an almost daily basis. Major new developments like the Palm Jumeirah require huge amounts of infrastructure. This includes new interchanges, highways and bridges to ensure that residents can leave for work in the morning and get home again in the evening, without facing the gridlock that the commuters from Sharjah suffer during the week. The same has happened in other regions. European cities, and later cities in the Far East, all experienced huge population growth and had to design roadways and other forms of public transport to prevent the cities from grinding to a halt. Roads and new road projects are typically the responsibility of the town or city in which they are located. It is in the interest of each town and city to ensure that its streets are properly and adequately lit. During the day, natural sunlight allows the human eye to clearly distinguish objects and determine their colour. This changes at night when the naked eye loses the ability to perceive colour and has to resort to distinguishing between differencent shades of grey. For car drivers, car headlights help to compensate for this deficiency, but only up to a distance of about 40 m. Drivers actually need to focus on the area 60-160 m ahead in order to anticipate any corrective manoeuvres that may be necessary. Without adequate public lighting, this is simply not possible. Nearly 50% of fatal accidents occur during the night-time, even though only 25% of all kilometres are driven at night. When designing street lighting, safety and comfort are the two main parameters that must be considered. A raft of international recommendations governing the design of street lighting is available, and is made up of various technical specifications like uniformity, glare and lighting levels. An important consideration is the ratio between the spacing of the luminaries and the height of the luminaries, as it affects the uniformity of the lighting and the levels required to illuminate the street below. The 1973 Europen energy crisis was a major catalyst for the reduction in energy use and maintenance costs for street lighting. It meant that designers began to look at new ways to rationalise street lighting to conserve energy, while maintaining sufficient levels to ensure that safety is not compromised. “In this region, the lighting levels applied are often far greater than what is strictly necessary, although it is becoming more rational with time as authorities become more aware of the costs involved and try to limit their installation cost and energy consumption,” says Niels Van Duinen, manager luminaires, Philips Lighting Middle East. The required lighting level depends on a variety of parameters such as traffic volume, ambient brightness and weather conditions. Some of these factors can vary at different times of the night or in different seasons. As a consequence, maintaining the same lighting level throughout the night is not the optimum solution. Dynamic lighting that utilises sophisticated management systems can be adjusted to suit the traffic flow at any given time. For example, high lighting levels are needed to give drivers the definition that they need to drive safely through heavy traffic, but when the road is quieter and traffic is sparse, less definition is required and lower lighting levels are sufficient. This was traditionally achieved by switching off some of the luminaires. While this reduces the level of lighting, it also dramatically impairs its uniformity and can leave dangerous blackspots on the road where drivers are effectively driving into the unknown. Modern systems can reduce the lighting level of each luminaire and reduce the overall lighting level, without creating blackspots. This is because each luminaire remains switched on. With tele-management systems, the lighting levels can be controlled automatically to suit the conditions on the road. Parameters such as traffic flow, the weather and ambient brightness are measured using sensors on the road. This information is regularly transmitted to a controller located in each feeder pillar. This segment-controller adjusts the lighting levels or switches the luminaries on or off accordingly. No extra wiring or transmitters are required as the information is all transmitted through the existing power supply lines. This means that every luminaire operates automatically and efficiently, without any reduction in performance. Costs are also reduced because the system is able to recognise when a light is about to fail or requires maintenance, eliminating the need for scouting trucks that search for faulty luminaires. Although optical and mechanical performance is crucial, aesthetics are of equal importance in an urban setting. To their credit, the cities around the Gulf spend vast sums each year maintaining decorative palm trees and other vegetation to make the cities look green and pleasant, but when it comes to street lighting, it often makes the cityscape look ugly, especially during the day. “This really should not be the case. The visual appearance of a road light can be pleasing, and at the same time achieve a very high performance,” says Van Duinen. “In the past people have focused heavily on the technical performance of a luminaire and not enough on the aesthetics. You should always consider what the luminaire will look like during the day, as well as the night since it is part of the urban furniture,” he adds. Other high tech lighting solutions that are available include LED (light emitting diode) road markings instead of traditional paint markings. These markings can easily be changed so road systems can be altered to accommodate different rates of traffic flow during the day, and make them operate more efficiently and ultimately reduce inconvenience to road users. ||**||

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