Chicago's O'Hare International Airport (search) is the world's busiest airport, and may be even busier if city officials get their way.

According to a plan from Mayor Richard Daley (search), the airport would go from seven to eight runways, and they would be re-arranged so that the airport can go from 100 take-offs and landings per hour to 130.

"It reduces delays overall by 79 percent and bad weather delays by 95 percent," said Rosemarie Andolino, executive director of the O'Hare Modernization Program (search).

But Sen. Peter Fitzgerald (search) says it isn't the runway patterns on the ground, but all the planes in the air that is causing the problems.

"The airspace in Chicago is the busiest, most congested airspace with the most near-misses of any airspace anywhere in the country, probably in the world," said Fitzgerald, a Republican who is retiring after one term in the Senate.

Towns near the airport say they don't want the extra air traffic above them, and the Federal Aviation Administration (search) is poring over the plans with a cautious eye. Others say a third option would be to build a third airport just outside city limits.

Click here to watch a report by Fox News' Steve Brown.