In late 2019, AIIB received a project financing request from the Government of India through the Department of Economic Affairs. Since then, AIIB and the Chennai Metro Rail Limited (CMRL) as the project implementing entity have worked closely on project preparation despite the challenges of the restrictions due to the coronavirus disease (COVID-19) pandemic.

With a total project cost of USD2,271.93 million, the Corridor 4 project runs from Lighthouse in the east to Poonamallee Bypass in the west, with 18 elevated stations (16.5 km) and 12 underground stations (10.3 km). The new corridor will ensure seamless multimodal transport across Chennai by providing integrated access to suburban rail, bus stations and the city’s main airport. Divided into several components, the project involves a parallel cofinancing arrangement with the AIIB, the Asian Development Bank (ADB), New Development Bank (NDB) and the Government of Tamil Nadu.

"The AIIB has taken on a vital role in project preparation and coordination between CMRL and the other parallel co-financiers, in areas including technical, procurement, environment and social," said T. Archunan, Director, CMRL Project. He added that the AIIB was instrumental in facilitating the discussion between CMRL and the parallel co- financiers, especially in the preparation of the environment and social instruments.

In Sept. 2021, the AIIB approved sovereign financing of USD356.67 million to construct the elevated section of Corridor 4. ADB proposed to finance the construction of the underground section; NDB is proposed to cover electrical and mechanical works, tunnel ventilation system, telecoms, automated fare collection, platform screen doors, traction and power supply; and the Government of Tamil Nadu is responsible for engaging the general consultant, construction of signaling, rolling stock, depot and staff quarters, permanent way, security features and procurement of the project land, resettlement and rehabilitation and payment of state taxes.

"The project aims to improve the public transport system in Chennai, which is in line with the Bank's strategy on transport and sustainable cities as well as with the AIIB thematic priorities of Green Infrastructure and Technology-Enabled Infrastructure," said Kishlaya Misra, the AIIB Investment Officer who leads the project team at the AIIB. "The project will enable a modal shift of passenger transport from carbon-intensive road-based transport to a low-carbon metro system thereby leading to greenhouse gas emissions reductions."

"AIIB was tireless in enhancing our understanding and adherence to the procurement and environmental and social performance requirements of multilateral development banks,” T. Archunan said. "They also provided extensive technical assistance in the civil tender preparation process and helped us develop a socially inclusive approach."

With AIIB's support, CMRL incorporated targeted interventions such as pre-defining women’s employment in the operations stage, conducting an annual survey of women passengers to assess the service standard as well as having dedicated stations operated by an all-women staff.

"We are incorporating climate-adaptive designs and measures to increase the project’s resilience to climate hazards," Kishlaya said. "Design parameters on climate adaptation are also incorporated into the project."

The project helps achieve AIIB's thematic priority on Technology-Enabled Infrastructure since it is using a building information modeling technology. Briefly, this means that three-dimensional graphic models of the project were rendered that enable easier integration of the design of various project components and identification of any potential conflicts, helping save on time and costs.

Now that the project has entered the implementation stage, more challenges have to be overcome, especially those due to COVID-19 measures. However, CMRL has been quick to adapt.

"We are using online conferences and other information technology tools to ensure timely completion of the project," T. Archunan said. "Our pre-bid meetings with tender participants were done online and in-person and we have strict protocols issued by the government that everyone must follow."

Along with COVID-19 response measures in the project's environmental management plan, CMRL has assigned their General Manager for Operations to be responsible for COVID-19 compliance monitoring.

"Because is it such a large-scale and complex project, technical planning is one of the challenges we had to face," said Wenyu Gu, AIIB Senior Investment Operations Specialist who is co-leading the project. "CMRL hired a Detailed Design Consultant (DDC) and a General Consultant to help with the technical matters for the project."

Construction work began in the second half of 2021. By the time the project is completed in 2026 and operational, CMRL anticipates several positive environmental impacts.

Gu said, "With more people using the rail network instead of the carbon-intensive road- based modes of transport, there will be road safety improvements, increased accessibility and mobility and fewer pollutants and emissions."