Over the weekend, Mayor Rahm Emanuel announced that O'Hare Airport would get a long-planned sixth east-west runway. This, after United and American Airlines agreed to help fund the $1.3 billion project that's part of the O'Hare Modernization Plan.

The layout and closure of some diagonal runways has caused a lot of controversy.

"The FAA, through it's standards and criteria encourages–especially very busy hub airports like O'Hare–to always have the aircraft lined up in parallel configurations," said Chicago Aviation CommissionerGinger Evansduring an interview with Eddie Arruza."That gives them the safest configuration and the most efficient configuration."

The new runway will offer "extensive departure capacity and extensive international capacity," Evans said.

"Further, the runway that it replaces, the diagonal runway, has some very significant safety issues," she added. "It also blocks the western access highway, and it also blocks the addition of gates. This whole package is intended to get O'Hare ready to be able add gates."

New gates and terminal expansion can't be built until the diagonal runway and a taxiway are moved, Evans explained.

"We are working on gates," Evans said, but noted that the runway project had to come first "by virtue of its physical constraints."

The announcement came only days after Mayor Rahm Emanuel met with activists protesting increased airplane noise that's come with runway additions at O'Hare. They are now blasting the city for forging ahead with yet another one.

The main group leading the charge to get relief is called Fair Allocation in Runways.

“We were pleased to finally meet with the mayor after two and a half years of asking for a response to the real and negative lived impact that people have been suffering with for two and a half years,” said Colleen Mulcrone of FAIR after the Jan. 27 meeting. “Unfortunately, the result of this meeting was more of the same and it’s business as usual. We were advocates for those diagonal runways that we want to keep to provide noise relief to the most communities."

The expansion announcement also seemed to blindside some elected officials who have played key roles in getting funding for O'Hare and who represent those communities impacted by airport noise.