That first phase – moving the runway – came in about $15 million under its original budget of $265 million. The next phase – installing the center aisle and other taxiways – is expected to take another year and a half. The runway officially reopened to air traffic a few minutes after 1 p.m. Monday. “Yeah, baby,” Villaraigosa said as he watched a slender American Airlines jet touch down on the runway, its wheels kicking up a powdery white plume of construction dust. Villaraigosa and other city leaders will receive a report in the next few weeks that will likely shape the debate over whether the northern runway merits a similar redesign. [email protected] (310) 543-6649160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! The southern runway at Los Angeles International Airport reopened to flights Monday after months of construction work, as questions about airport safety turned to the airport’s northern runway. Construction crews have spent the past nine months ripping up and rebuilding the southern runway, clearing space for a new taxiway that will give airplanes more room to maneuver. The $333 million project addresses a long-running problem of errant aircraft getting dangerously close to other planes while taxiing at LAX. Most of those close calls have happened on the southern runway, and airport officials have described the work there as crucial to passenger safety. But the runway on the north side of LAX has the same configuration. “Right now, there is no demonstration that the north runways are the same kind of safety threat that the south runway was,” Mayor Antonio Villaraigosa said. “First things first.” LAX has two pairs of runways, one on the north side of the passenger terminals and one on the south, each with two separate landing strips. Both look like gigantic, concrete “equal signs.” In general, airplanes land on the outside runway, then must cross the inside runway to get to the gates. Occasionally, something goes wrong and an airplane rolls onto that inner runway while another airplane is landing or taking off on it. LAX had the worst record in the country for that kind of potentially disastrous mistake from 2000 to 2003. The airport has recorded 37 such mishaps in the past five years, 28 of them on the southern runway. One solution, airport planners decided, was to pry apart the two southern landing strips and install a center aisle between them. That would slow down airplanes by forcing them into a series of turns, and give them a place to wait for clearance to cross the inside runway. Work crews began breaking up the southern-most runway in July, then rebuilt it about 55 feet closer to El Segundo. The project involved enough concrete to pave an eight-lane highway from LAX to downtown, said William Withycombe, regional administrator of the Federal Aviation Administration.