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The Aarey Colony Metro Depot Conundrum: Gain Vs Strain to Environment


Continuing with our effort to understand of Greens Vs Greens conundrum over the Aarey Milk Colony Depot of the Mumbai Metro Line 3 (MML – 3) we decided to look into the ‘Gain Vs Strain’ to the environment.

We spent our time studying the Metro rail operations based on the scientific data sets available of the project.

Mumbai is so polluted due to the large number of vehicles in the city. In my understanding, the temporary strain on the environment caused by cutting 2,141 trees at Aarey Milk Colony in terms of CO2 sequestration, will be compensated just by four days of Metro Line 3 operations. The damage envisaged over the trees’ lifetime will be compensated by 80 days operations.

The Mumbai Metro is an infrastructure project registered with the United Nations Framework for Climate Change (UNFCC) under the Clean Development Mechanism (CDM).

Let me elaborate on this aspect of the project a little more by explaining to the readers about the inclusion of the Mumbai Metro Rail Corporation (MMRC) in the MRTS projects (Metro Rail and Bus Rapid Transport) Programme of Activities (POA) – COs emission reduction.

Delhi Metro Rail Corporation which is considered to be one of the successful Metro operators in the world, has launched the framework of Programme of Activities (POA) through which any MRTS projects (Metro Rail and Bus Rapid Transport- BRT) in India can earn Clean Development Mechanism (CDM) benefits.

The Programme of Activities is a modality of project development under the CDM of the United Nations Framework convention on Climate Change with the aim to allow replicable projects in to CDM by an entity.

The POA contributes to environmental improvement, as it reduces the pollution levels in the city by using electricity instead of fossil fuels in case of Metro.

Activities under the POA reduces the Green House Gases (GHG) emissions by encouraging the commuters to use efficient means of transportation and results in contribution to the environmental benefits.

The POA contributes to the technological wellbeing to the country as it utilises the most efficient, modern and advanced technology available for the transportation to meet the city needs.

Hence, the POA clearly meets the sustainable development criteria and objectives specified.

On January 2012, DMRC launched the first transportation Programme of Activity (POA) in India to streamline and fast track CDM registration of upcoming metro projects.  The POA got registered on 9thOctober 2014 with UNFCCC in which DMRC has been described as Coordinating Managing Entity (CME) for MRTS POA 9863.

The Phase II operations of Metro Project of DMRC is already a CDM registered project and based on its past experience DMRC has decided on a POA approach to reduce cost, risk and complication of CDM registration process.

Since, DMRC enabled to demonstrate GHG mitigation and availing carbon credits through this POA, upcoming Metro projects across India need not to interact with multiple agencies like validators, CDM consultants, national CDM authority, UNFCCC, buyer etc.

Apart from the role of Coordinating Managing Entity of POA 9863, DMRC acted as a CDM consultant to MMRC’s model shift project to register it as a CDM project under MRTS POA 9863 with UNFCCC.

DMRC carried out the responsibilities as per the scope of work which included submission of inception report followed by CPA DD document, carrying out the traffic survey and assisting in validation of project.

The base line methodology for calculating reduction in CO2emissions is based on ACM0016 version 04.0 methodology registered with UNFCCC.

Under the said methodology, base line emissions, direct project emission and indirect project emissions are calculated considering various factors such as average annual flow of passengers, total number of passengers surveyed at the stations (PSPER), emission factor of various modes of transport per kilometer per passenger, emission factor of the grid, occupancy of the various modes of transport, fuel consumption by various modes of transport per kilometer, a leakage factor due to transmission of electricity, a leakage factor due to change in capacity of the various modes of transport (occupancy) average vehicle- kilometer travelled and consumption of traction energy.

These aspects are considered to calculate the reduction in emission of CO2.


The figure of 49,43,784 number of passengers surveyed in a week at the stations is a registered figure in POA DD which has been considered to estimate baseline emissions as a common figure.

Project emission means an addition of direct project emission and indirect project emission.

Baseline emission means the emissions released by various modes of transport on the road in absence of Metro. CO2emission reduction is the figure calculated after deduction of project emissions from base line emissions.

For the year 2021, baseline emissions calculated are 4,70,002 ton of CO2and project emissions are 2,30,287 ton of CO2. Thus, emission reduction of CO2in the year 2021 is 2,39,715 and annual average emission reduction is 2,61,968 ton of CO2.

DOE (Designated Operational Entity) that is validator (KBS Certification P. Limited) who is registered with UNFCCC as a DOE have validated the data presented by DMRC in their CPA DD document and registered the project with UNFCCC.

Let’s also look at the evaluation of company Terracon Sustainable Solutions on the Mumbai Metro Line 3 project. In its report dated July 18th 2019 it stated

Based on the DPR prepared by RITES and a list of 2702 trees received from the Mumbai Metro Rail Corporation Limited (MMRCL), we have arrived the following values for:

  1. The daily road carbon emissions that the metro project would replace and,
  2. CO2 sequestration by the trees to be cut / transplanted at the Aarey Colony. Carbon Emission:

Considering the CO2 emission of car being 135.32g CO2 /km (Weighted Average) every metro trip replacing 12% of the personal cars and taxis on road, a total CO2 emission for cars and taxis replaced by one trip of fully loaded metro train = 324kg CO2

Carbon Sequestration:
Total CO2 sequestration by 2702 trees is 12,79,062 kg for the designated lifetime.

Thus, considering an age of 20 years for these trees (assuming the accelerated growth age of the trees for CO2 sequestration) will be 63,953 kg per year.

It is calculated that to offset 63,953 kg CO2 increase, i.e. the impact of removal of 2702 trees, on annual basis, only 197 fully loaded trips of metro trains will suffice.

The methodology followed to calculate the CO2 sequestration is attached as an Annexure.

Calculation of Sequestration:

1. CO2 emissions from cars and taxis replaced by metro per day-

CO2 emission of a car= 135.32 g CO2/km (Weighted Average)

Estimated average distance covered by a passenger per trip every day= 12km 􏰀

CO2 emissions of a car for 12 km per trip= 1623.8 g CO2= 1.623 kg CO2

Total intended occupancy of a metro in one trip = 3000 people Considering 12% passengers to be replacing cars and taxis with metro

􏰀Cars and taxis per trip replaced by metro= 12% of 3000= 360 vehicles per trip

Since, surveyed occupancy of a car= 1.8

Number of cars and taxis replaced by metro per trip= 200

CO2 emissions from cars and taxis replaced by metro per trip = 324 kg of CO2

To offset 63,953 kg CO2 increase on annual basis from 2702 trees, 197 trips of metro will suffice.

Further more the MMRCL in its communication has stated that it has adopted sustainable mitigation measures for the temporary environmental strain the project might cause. It has planted 14,346 trees with 6”x 12” girth and 12 -15 feet height of native variety and also planted 9,500 trees as per the Forest Department norms under CSR.

A total 23,846 trees have been planted at different locations including the degraded areas of Borivali National Park. The trees are of good quality of plant of native variety like Sita Ashok, Kadamb, Arjun and Kanchan.

Reportedly 13,000 additional trees are also expected to be planted by MMRCL. They are currently in discussion with the Maharashtra government to find suitable land to plant more trees.

In effect while the felling of trees will have some immediate strain to the environment, the Mumbai Metro will have a long-term positive gain to the environment is my view.




Savio Rodrigues

Savio Rodrigues Founder & Editor-in-Chief GoaChronicle.com

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