After decades of debate and scrapped blueprints, crews are moving dirt and pouring concrete at O'Hare International Airport for the largest airport expansion in the nation's history.
The seven-year, $15 billion project is designed to eliminate most weather-related delays and erase O'Hare's reputation as the perennial knot in the nation's aviation system.
"It should make the intolerable delays a thing of the past," said Joseph Schwieterman, a transportation expert and economics professor at DePaul University.
Still, some aviation analysts question how quickly the plan will bring relief and whether it can live up to its billing when completed in 2013. Questions also loom over the project's financing, which relies partly on a shrinking pool of federal money and airlines that have been bleeding red ink for years.
And the project faces a fierce legal challenge by residents of two adjacent suburbs, where hundreds of homes and business are slated for removal and 1,300 graves are to be relocated.
"I can't imagine anything more sacrilegious than rolling pavement over pre-Civil War graves," said Bob Sell, a spokesman for St. Johannes Cemetery, where dozens of his relatives are buried.
Much of O'Hare's problem can be traced to its pretzel-like runway configuration, a remnant of its origin as a military airfield during the 1940s. The intersecting layout makes it tough to land planes in Chicago's frequent fog and wind.
"That airfield has probably the most complex geometry of any airfield in the United States ... and possibly the planet," said Mary Rose Loney, a Miami aviation consultant who was Chicago's aviation commissioner in the late 1990s.
Even in fair weather, the airport can be trouble. Since March 21, the Federal Aviation Administration has investigated three close calls on O'Hare's intersecting runways. In one, planes came within 100 feet of each other - the most serious near-crash on a U.S. runway in several years, the FAA said.
When visibility drops or wind gusts, air traffic controllers close one of the three arrival runways to eliminate the risk of collisions. The ensuing bottleneck means planeloads of passengers must wait on the ground in other cities for Chicago's weather to clear.
"O'Hare is so centrally located and has so much traffic that when things get out of whack, the whole system can be impeded very quickly," said Darryl Jenkins, a consultant to numerous airlines.
It's a phenomenon seen firsthand by Wayne Carpenter, a 37-year-old private-equity fund manager who has been flying out of O'Hare weekly since 1991.
"I avoid O'Hare at all costs when I'm flying across the country," he said. "It just seems like I don't see these kinds of delays anywhere else."
O'Hare ranked dead last in on-time performance among the busiest U.S. airports in 2004 - prompting the FAA to cap the number of landings there last year at 88 arrivals an hour between 7 a.m. and 8 p.m., down from more than 120. That helped O'Hare's on-time performance a little, but it's only a temporary fix.
Work under way on the expansion's first phase is expected to cut delays by about two-thirds. The first step is a new runway on the airfield's northern edge that will keep three arrival runways open in bad weather. It's due to open at the end of 2008.
The project to untangle O'Hare will create a mostly parallel layout, rather than a crisscrossing tangle. The net result will be just one additional runway - eight instead of seven - but will greatly ease flight operations, planners say.
A new terminal and western access to the airport also are planned.
FAA officials say parallel runways are the ideal design. They point to the success of Dallas Fort-Worth and Denver airports, for example, which have the same number of runways as O'Hare but boast far better performance.
The average delay per aircraft at Dallas, for example, is about 10 minutes. At O'Hare, the average was approaching 20 minutes before limits in 2004, according to the FAA. O'Hare's expansion promises to chop that figure to 5 minutes.
City advances plan to expand airfield despite opposition.
The center will monitor 1 of 2 new runways at O'Hare Airport.
Chicago has promised that its $14.7 billion plan virtually will eliminate late and canceled flights during bad weather.
The temporary halt of the $15 billion runway project would have pushed the project back many months.