600 people, 100 types of equipment, and a bit of 'chicken parade': What went behind repair of one of world's busiest runways

It took 600 people and 100 different kinds of equipment, working in clock work precision for six hours a day, three days a week and over two months to complete the repair work of the main runway of Mumbai's Chhatrapati Shivaji Maharaj International Airport. And yes, it needed a bit of a "chicken parade" too.

Mumbai's the busiest one-runway airport in the world.

The repair, which gets over on March 30, was done of the intersection of the main runway, and the secondary runway that is used for four hours a week. The work forced the airport to be shut for six hours every Tuesday, Thursday and Saturday, from 11 am to 5 pm.

"It was after a 'health check' that it was decided to repair the runway. While the structure is strong, the top part of the runway needed repair," said a spokesperson of Mumbai International Airport Limited, the GVK Group-controlled operator of the airport. The intersection was last repaired in 2009-2010.

The runway handles about 1,000 flights a day, clocking a little over 45 take-offs and landings an hour. London's Heathrow airport is the second busiest single-runway airport.

But during the closure, the airport's traffic reduced by about 300 flights a day.

The preparation

Due to the heavy traffic at Mumbai airport, maintenance of its runways is a tough call. The main runway is tended to for just 40 minutes a day, from 3.20 in the morning. There is another 15-minute window, every Monday, from 1.45 pm.

But during all this, the intersection is still open to traffic, because of the secondary runway. The intersection is unique to the Mumbai airport, which opened in 1940, and is reflective of a design fault that couldn't be corrected because of lack of land.

Thus when it came to repairing the intersection, the airport had to be partially shut down. "We needed to plan for six months before starting the work," said the MIAL executive.

The operator wanted to do the work in April-May. But as the two months coincide with the peak, summer vacation traffic, airlines asked for the repair to be advanced to February. The repair work started on February 7.

Wear and tear

Every time an aircraft lands, it leaves behind up to 20 kg of rubber - depending on the plane's make - on the runway. The rubber deposit happens when the wheels touch the ground, the impact also emitting a puff of smoke.

Among aircraft, the Boeing 777-300 wide-body plane does most of the damage as it has a narrow wheel base balancing the whole weight.

Though the runway is cleaned of the rubber through water blasting, the process also damages its surface. "Heavy rains also damage the surface," said the spokesperson.

The repair

MIAL set up a plant within the airport area to manufacture concrete used to lay the runway. "This helped, otherwise getting 100 dumpers a day would have been a major logistics challenge," said the executive.

The plant would start at four in the morning, so that the concrete would be ready when the repair work would being at 11 am. "Each day we would work on an area of about 5,000 square meters," said the executive. The total area to be covered was about 50,000 square meters.

Senior officials would hold meetings in the morning, and later in the evening to take stock.

At the end of each day's work, about 20-30 workers would line up to do the chicken parade -- to pick anything, including stone or pebble that would be left behind. In South African military terminology, Chicken parade means picking up litter and cigarette butts in an area. "It is important so that it doesn't harm the aircraft when it lands or takes off," said the spokesperson.

In total, the men worked for 22 days to complete the work.

"About 98 percent of the work is done. It will be all ready by 5 pm on March 30,' said the MIAL official.