See how Chennai Metro is adopting green concepts in its underground stations

Chennai Metro

The four underground stations of the Chennai Metro Rail (CMRL) operational in Phase 1—Thirumangalam, Annanagar East, Annanagar Tower and Shenoy Nagar—have recently received Platinum rating by the Indian Green Building Council (IGBC) for adopting green concepts in design, construction and operation.

Imffered the prospect of metro stations in India speeding towards eco-friendly and pollution-free mass transit systems in future. This journey has been embarked upon to reduce the carbon footprint, provide the best metro system to the people of Chennai, and improve the city's overall landscape in future.

The plan
The stations have been designed with the effective use of natural daylight for luminance. To ensure the stations receive optimum daylight and fresh air ventilation, CMRL have used tempered laminated glass on three faces of the station entrances and louvers on the fourth face of the entrance. Also, the Shenoy Nagar Station has been provided a skylight opening with tempered laminated glass on the roof and walls for daylight. Further, indoor air quality during construction (through vent fans) and at the operation stage has been maintained for the platforms and concourses at 11 cfm, for the station controller room and office spaces at 5 cfm, and for retail areas at 7.5 cfm. An environment-friendly job site was created by monitoring and maintaining the air quality and noise pollution (<65 dB(A) during daytime and <55 dB(A) during night time as per CPCB standard for commercial area) within the limit during construction.

Efficient fixtures
Efficient strategies were adopted at the metro stations in the areas of energy and water in planning and designing. Energy-efficient electrical equipment such as transformers, motors, light fittings, etc, has been used. LED lights with 60 per cent savings and energy-efficient vac have been installed. A supervisory control and data acquisition (SCADA) system has been used for energy and power factor control. Also, Afcons has ensured reduced lighting power density >60 per cent at the concourses, platforms and public interface levels, efficient building envelope, improved efficiency in HVAC equipment and systems >15 per cent above ASHRAE 90.1-2010. The stations also have machine-room less type lifts installed that are energy-efficient, and auto sensor escalators and elevators with three-phase VVVF drive. Variable speed drives were used in the pumps and motors. CFC-free eco-friendly refrigerants (R134a) and halon-free fire suppression systems were used. Also, the commissioning, monitoring, measurement and verification plan included comprehensive energy auditing for all HVAC, lighting, power backup systems, and elevators and escalators. Further, in the area of water conservation, the stations have made use of low-flow fixtures, resulting in 45 per cent savings. Rainwater harvesting has been undertaken at the stations.

Moreover, smart monitoring or smart passenger services have been introduced in the development of these stations. Platform screen doors (PSD) in the underground stations have been installed to instill passenger safety, energy savings and efficient tunnel ventilation. Signage and a numbers of display boards have been provided to guide passengers.

Material and waste management
The materials used in the construction of these stations contained an average of 22 per cent of recycled content. Further, 97 per cent of the materials used in these metro stations was brought from within 400 km of the project site. Material storage and protection was looked after. Measures were also taken to prevent site erosion and sediment runoff. In terms of waste management and recycling, 100 per cent of the construction waste was handled by proper disposal, sale and diversion. Afcons is diligently maintaining the principles of construction waste segregation and collection by reusing, recycling and diverting more than 95 per cent of the civil and interior wastes. For the construction site being temporary in nature, sewerage was disposed to a sewer line connected to the Chennai Corporation sewerage treatment plant (STP). Afcons has undertaken extensive construction waste management practices at these stations.