Rapid urbanization encourages proportionate enhancements to be made in the appropriate urban public utility infrastructures. Such public utilities are energized majorly by non-renewable sources; therefore, it is critical to conserve energy & enhance the quality of life for the people in Chennai City. Streetlights, as one of the major consumers of energy in the public utility infrastructure segment, was evaluated for optimization. 

The roadmap has 3 stages:

Stage 1: Converting from sodium-vapor lights to LED lights
Stage 2: Centralized real-time monitoring & proactive maintenance, and 
Stage 3: Consumption optimization with diming sensor provisions with available LUX & traffic flow 

As a part of Stage 1, 70% of streetlights in the city have been changed to a LED-based lighting system which has resulted in savings of INR 68 crores. Area Based Development under the Chennai Smart City Initiative started Stage 2 by selecting a pilot location (T Nagar) in the city and it has been successfully commissioned. Currently, Stage 2 & 3 activities are planning to be started in the ABD area.

Context 
The Greater Chennai Corporation maintains 2,77,902 streetlights and the total charges for its electricity consumption amounts to nearly Rs 4.64 crores a month. The street lamps were first introduced in 1785. Till 1857, there were only 200 oil light lamps. By the year 1910, there were 6,500 oil lights. Electric street lighting was introduced for the first time in 1910. The improvement of lighting on this account was so immense that the number of electric lights gradually increased till the years of 1924-25 when all the lights were completely replaced by electric lights.

Ever since, a fair amount of the department's expenditures have gone towards the maintenance of sodium-vapor lamps, which have a high burn-out rate. Given their high-consumption of electricity and high maintenance cost, it was proposed to switch to LED lights for energy and cost savings.

The work order for the project was commissioned on 4th October 2017 and the project was slated for completion on 5th January 2018. The project cost was estimated at Rs 3.44 crores. The project was completed by 2nd January 2018 at a cost of Rs 2.94 crores, and it was funded by the Smart City Mission.

Solution
The Smart Street Lights have been installed as an open standard solution that is highly scalable and interoperable. The solution is designed for SCADA based monitoring with an automatic ticket-generation tool in case the light is not functioning. All of these technological features show that lights can be monitored even from remote locations and the functionality of the lights can be taken into account. This enables speedier replacement and low maintenance in case of repairs. The scalability factor ensures that the entire region can shift to a plan of energy efficiency and that it is easily replicable irrespective of the topography or demographic pattern of the region.

Scope of Implementation
The project was initiated for the ABD area of T Nagar. In this project, 1,772 lights were changed from sodium-vapor lamps to LED lights. Spanning 6.92 sq. km., T Nagar is already an established development in the CBD region of Chennai.

On average, nearly 2 lakh pedestrians use the streets of T Nagar and on a festive day the market area alone witnesses up to 20 lakh persons. Hence, good lighting adds to better security and mobility in the region.

Features 
Smart Street Lighting has the following innovative characteristics:

1. Intelligent Lighting: It is able to intelligently assess the approximate vehicular movement during the early hours of the day. This is operated with the use of a proximity sensor which can control the availability of LED lights.
2. Luminosity Control: Depending on the actual daylight available the luminosity of the light is adjusted. This real-time data helps to manage the voltage at a pole level such that the optimal luminosity is maintained. 
3. Proactive Governance: It helps the administration monitor the poles and lighting in the area without having to wait for citizen feedback or field officials to report back. It negates delays in attending to maintenance issues.
4. Pole-level monitoring: The functional performance of every pole is monitored so that any repair work can be taken up on an immediate basis.
5. Reduced Carbon Footprint: LED lighting is a greener alternative to sodium-vapor lamps which account for a larger carbon footprint.
 

Results / Impact 
Apart from the reduction in the carbon footprint, the savings in energy consumption and cost to government is given below:

Since the spread of the LED light is over a larger radius than the conventional sodium-vapor lamps, the number of dark pockets in the region has been considerably reduced. The better lighting also invites increased footfall in the commercial areas.

Some of the expected impacts include:

1)    Reduction in crime rates in the region
2)    Increase in economic activity
3)    Reduced maintenance cost since the die-out is slower with LED lights
4)    Improved color rendering
5)    Comparatively less heat generated and hence, less energy wasted

Replicability / Scalability 
The project is highly scalable and has already been rolled out for 70% of the city's street lights, apart from the ABD area of T Nagar. The remaining 30% is in the rollout phase and is to be completed in the coming months.

The smart streetlights are designed with SCADA system that would enable them to be monitored from the Command & Control Centre. The performance of these lights can be directly correlated to the trends in crime rates, mobility, economic activity, and productivity of the region. Thereby, the data collated from the various projects in the Smart City Mission can be collaboratively analyzed to evaluate the performance of these lights and their impact on the livability of the city.