Los Angeles (CNN) -- The closure of a mountain highway pass in the heart of the nation's second-largest city -- an event anticipated to be so calamitous to car-loving Southern California that it's been dubbed "Carmaggedon" -- is scheduled to begin at 7 p.m. Pacific on Friday. That's when crews will begin closing ramps on Interstate 405 where it passes over the Santa Monica Mountains, California Department of Transportation officials said. At 10 p.m. Pacific, crews will begin closing lanes, and by midnight, the 405 will be eerily vacant -- a "carpocalypse," some say -- for the next 53 hours....