Armed with clearances from the Airports Authority of India (AAI), Metro Railway invited bids for the extension of the Yellow Line, which will cover 6.8 km from the Airport to Birati. The Rs 13.30 billion contract includes the construction of the Birati and Michael Nagar stations. On July 5, a news report titled ?Airport Raises the Bar, Barasat Metro Vaults Past Height Hurdle? indicated that the metro line, which had missed several deadlines, was progressively overcoming obstacles. The AAI had resolved the height restrictions for cranes needed for construction and permitted metro work outside the airport. The Yellow Line is planned to start at Noapara and end at Barasat via the airport. Last week, Metro Railway called for bids for the civil construction of the Yellow Line?s 6.8 km underground extension from Biman Bandar (Airport) to Birati. This move followed the AAI?s decision to permit the use of 18-meter-tall cranes for constructing the Airport-New Barrackpore segment of the 11.2 km Noapara-Barasat line. Additionally, the AAI issued the much-anticipated No Objection Certificate (NOC) for work between the airport and Michael Nagar. Discussions are ongoing to resolve the issue concerning the New Barrackpore station, which is situated on the flight path of planes near the northern end of the main runway. According to a metro official, ?The Rs 13.30 billion contract is part of the Yellow Line?s 11.2 km extension to Barasat in the north-eastern suburbs of Kolkata. It includes the construction of a 3.6 km metro tunnel, an underground metro station building at Birati, and subway work for Birati and Michael Nagar stations.? The official added that the successful bidder would need to complete the project within two-and-a-half years. The metro tunnel, which will run along the city airport?s boundary wall, is planned to be constructed using the RCC (reinforced cement concrete) box-pushing method, without the use of tunnel boring machines (TBMs). The Birati station will be built using the cut-and-cover method.