Street lighting is the most ignored and the least efficient of urban services. It may appear ubiquitous but, in reality, public lighting in most cities is inadequate and has led to poor road safety conditions and loss of precious energy. Concerned by the bad quality of service and impelled by Justice Verma Committee’s recommendations in the aftermath of the shameful Delhi rape to provide ‘street lighting everywhere,’ the Ministry of Urban Development recently sent an advisory to all States to strengthen public lighting in their cities. Infrastructure benchmarks recommend that local bodies should provide lights every 40 metres and the level of illumination has to be a minimum of 35 lux. Many cities may claim that they have adhered to these norms, but the truth is that a large number of street lights do not function properly. For instance, in Karnataka towns, about 30 per cent of the street lights are dysfunctional. The local bodies, which periodically survey and evaluate urban services, repeatedly and conspicuously fail to enumerate lighting facilities. But it is evident from the estimate of the high powered expert committee on urban infrastructure services that unmet demand for improved public lighting, valued at Rs.9,594 crore, persists.
Performance is another issue of concern. Street lights consume a total of 6,131 million kilowatt-hours in a year (Bureau of Energy Efficiency, 2007-08 figure) and about a quarter of this consumption could be easily reduced. Many cities continue to use Mercury and Sodium vapour lamps, which have a poor lamp life and relatively low luminous efficacy, defined as the rate of conversion of electrical power to light. On the other hand, Light Emitting Diode (LED) lamps have 50,000 hours of life and are highly efficient. For a given unit of power, LED lamps provide better light. By converting existing lights to LED lamps, cities can reduce energy use, expenditure and green house gas emissions. Choosing the right kind of lamp alone is not enough. The lighting system too needs innovation. Most local bodies use manual switching systems, which keep street lights on for a fixed time. Studies show that if such static systems are replaced by smart ones, which adjust operational time according to ambient lighting conditions, modify intensity during lean traffic and correct voltage, cities could save about 20 per cent in energy. Revamping street lighting and using LED lamps would entail higher capital cost, but the savings in terms of operational and maintenance expenditure would offset this quickly. What is more important is that efficiently lit streets would provide a safe environment and create a sustainable city.