Green Ways: Sustainability initiatives in metro rail design, construction and operations

In January 2015, Indian Railways (IR) formed the Environment Directorate within the Railway Board to assume responsibility for supervising all environmental management programmes, recognising its significance as a crucial component of building world-class infrastructure. Subsequently, the railway and metro systems both implemented measures to enhance the efficiency of their environmental management initiatives.

In order to establish the metro as a sustainable and environment-friendly mass transportation system, it is crucial to adopt an integrated approach that prioritises resource efficiency. These efforts can help contribute to a low-carbon and eco-friendly environment.

Key milestones so far

Metros in India have already taken the first strides towards mitigating their carbon footprint and alleviating environmental damage. In the latest development, the Delhi Metro Rail Cor­poration (DMRC) has successfully transitioned to being completely green. It has been recognised as the “World’s First Green Metro” due to its strict adherence to the green building guidelines set by the Indian Green Building Co­uncil (IGBC).

DMRC has been associated with sustainability efforts for many years. Back in 2008, DMRC achieved a significant milestone by becoming the first recipient of carbon credits from the United Nations (UN). Following this, in 2015, the metro achieved another first by being in­cluded in the Clean Development Mechani­sm of the UN. Moreover, DMRC has now obtained multiple green certifications for its Phase III and Phase IV stations and depots. Additionally, even during its construction phase, the metro system consistently strived to implement en­vironmentally sustainable methods. For example, DMRC replants 10 trees for each one that is cut down during the construction period. So far, DMRC has planted over 500,000 trees under Phases I, II and III.

In 2023, as many as 10 “green stations”, along the Dahisar East-An­dh­eri East segment of the 16 km-long Mum­bai Met­ro Line 7, have been bestowed with platin­um rating by the Gre­en Mass Rapid Tra­ns­port Sy­stem Rating Prog­ramme of the IGBC. These st­ations are Ovari­pada, Rashtriya Udy­an, Devi­pa­da, Magathane, Poisar, Akurli, Kur­ar, Dindo­shi, Jogeshwari E. and Aarey. This ce­rtification em­phasises their co­mpliance with sustainability measures such as water and energy efficiency.

In recent times, Chennai Metro Rail Limited received the International Green World Award for implementing eco-friendly initiatives such as cutting down on energy and carbon emissions and utilising solar energy to establish a sustainable framework that strives to reduce environmental impact throughout the construction and operation phases, while also ensuring a reliable and secure commute experience.

Kochi Water Metro is also expected to reduce 44,000 tonnes of carbon dioxide emissions every year. Additionally, the Lucknow Metro has become the first metro in India to have 100 per cent LED lighting in trains and stations. Other metro systems are following suit by staying committed to environment-fri­endly practices and making similar efforts. Current efforts by various metro authorities include utilisation of renewable and alternative energy sources, water conservation via rainwater harvesting, afforestation, waste management, regenerative braking systems, planting trees in and around stations and de­pots, energy-efficient electric equipment and solar roofs.

Renewable energy-based solutions

Metro rail corporations in almost all cities are adopting renewable energy on a large scale for the purpose of reducing their operational costs while ensuring sustainability. In this regard, the Sahibabad Regional Rapid Transport System station, which is part of India’s fastest urban rail track, will be powered by 1,100 solar panels and is being constructed to promote cross-modal connectivity.

Similarly, as of April 2023, DMRC receives 35 per cent of its total energy supply from rene­wable sources and aims to step it up to 50 per cent by 2031. Around 30 per cent of its renewable energy comes from the off-site share of the Rewa solar power plant in Madh­ya Pradesh, 4 per cent from rooftop solar panels and 1 per cent from the waste-to-energy plant in Ghazi­pur. Though Delhi Metro’s currently installed rooftop solar panels at 142 locations can generate 50 MWp, DMRC is preparing the pilot installation of 100 kWp of vertical solar photovoltaic panels on its viaducts and vertical solar panels on both sides of the viaducts of elevated corridors. Addi­tionally, the National Capital Region Transport Corporation aims to achieve 70 per cent of the total energy requirement of the Delhi-Ghazia­bad-Meerut corridor through solar power.

In a significant step towards sustainability and cost-saving measures, Pune Metro has installed solar panels on the rooftops of stations and depots. Nine of these solar plants have already been constructed and the remaining installations will conclude by February 2024. The total solar capacity proposed for all elevated stations and depots is 9 MW, which will reduce their environmental impact. Additio­nally, the installation of facilities to generate 5 MW of power will be completed soon.

A solar plant with 1.28 MW of capacity has been installed at the premises of the administrative building of Lucknow Metro, along with a solar pla­nt of 1.1 MW capacity at the Transport Nagar Me­tro Depot. As of August 2023, these solar pla­nts have generated 3 MUs of electricity.

Other innovative measures

In recent times, the preference for metro tunnelling has shifted to the use of refurbished tunnel boring machines (TBMs) as opposed to brand new TBMs. In early 2023, TERRATEC, a renowned designer and manufacturer of TBMs, launched an earth pressure balance (EPB) TBM for Surat Metro, an under-construction rapid rail transit system in Gujarat. This unit is a refurbished 6.61 metre diameter EPB TBM, which will be used by J. Kumar Infraprojects for Phase I of the Surat Metro Rail Project (UG-02).

Similarly, a refurbished mixed-shield EPB machine called TBM Bhadra, manufactured by Herrenknecht, along with another machine, TBM Tunga, will be used to build a total of four tunnels in the Bengaluru Metro.

DMRC has used Tech Geo PR 30 non-woven geotextile in the tunnels of Delhi Metro. It provides protection, separation and drainage between the top shotcrete lining and the yellow geomembrane sheet. Additionally, electrically powered equipment, noise control mechani­sms, robotic excavators (as used in Mumbai Metro), and electric drum cutters are a few of the sustainable measures that have the potential to be scaled up further in the future.

Furthermore, DMRC is planning to initiate rainwater harvesting in all the elevated stations of the Phase IV metro. A total of 52 recharge pits have been proposed for this. Three identified priority corridors for this are Janakpuri West-RK Ashram (Magenta Line), Majlis Park-Maujpur (Pink Line) and Aerocity-Tughlaqabad (Silver Line).

The rainwater harvesting system located between MG Road and the Byappanahalli metro station is a noteworthy example of Bangalore Me­tro Rail Corporation Limited’s Namma Me­tro’s effective groundwater recharge efforts. The system effectively gathers and replenishes each individual raindrop, demonstrating the significant potential for implementing sustainable wa­ter management practices. In the near future, the metro authority may also assume the res­pon­sibility of creating this system across the Pink, Purple and Green Lines.

The way forward

As a sustainable urban transport system must fundamentally practise multimodal integration, an increased focus on providing last- and first-mile connectivity is key for the future of Indian metros. The expected cost of constructing metro projects varies, depending on the kind of metro system. As per ICRA, the cost for at-grade metro is projected to be between Rs 0.9 billion and Rs 1.2 billion per km; however, the cost is considerably higher for elevated metro and underground metro projects, ranging from Rs 2 billion to Rs 10 billion per km. In light of this, the government has put forth cost-effective alternatives such as MetroLite and Metro­Neo. With various projects such as Banga­­lore MetroLite, Nashik MetroNeo, Chen­nai Me­tro­Lite and Warangal MetroNeo being at different stages of development, these systems ha­ve the potential to emerge as the most via­ble alternatives to traditional metro systems in the future, owing to the relatively lower capital and operations and maintenance cost.

Moreover, green energy is expected to beco­me the most favoured option for supplying electricity to India’s extensive metro networks.

Harman Mangat