The road connecting terminal T3 to T1 of the Delhi airport will remain closed for the next three weeks starting today, Delhi International Airport Limited (DIAL) said.Why is road connecting Delhi Airport Terminal 1 to Terminal 3 closed?The road connecting terminal T3 to T1 of the Delhi airport will be closed for three weeks as it is being upgraded, its operator Delhi International Airport Limited (DIAL) said. However, the carriageway connecting T1 to T3 will remain open for movement of traffic coming from T1, it said."Due to the ongoing upgradation work, traffic movement on the carriageway connecting T3 to T1 of IGI (Indira Gandhi International) airport, through the underpass, will remain suspended for three weeks from today," the DIAL mentioned.Issuing an advisory to air passengers who are planning to travel from T-3 to T-1, Delhi Airport said, “Those planning to travel from T3 to T1 are advised to take the national highway (NH-48 or old NH-8) to reach T1 through the Radisson roundabout.”With this, it is expected that the travel time from Terminal 3 to Terminal 1 may increase by 20-25 minutes now for the next three weeks. So, air travelers have should plan their travel accordingly.Delhi Airport, also known as Indira Gandhi International Airport and IGI Airport, is the only airport serving the city of New Delhi. The Airport is the busiest one in India in terms of passenger traffic and cargo.The Skytrax World Airport Awards named Delhi's Indira Gandhi International (IGI) airport the finest in India and South Asia for the fourth year in a row, according to an official statement released on June 17.According to the statement, the Skytrax World Airport Awards are based on an annual global airport customer satisfaction survey that evaluates customer service and amenities at 500 airports.