This weekend, the busiest freeway in the United States, Interstate 405 in Los Angeles, will close for bridge demolition to allow for a northbound carpool lane. The stretch handles 375,000 cars on a typical day and up to 500,000 on the weekends. This event has been dubbed "Carmageddon." The 405 Freeway over Sepulveda Pass will be closed for 10 miles between I-10 to US 101 northbound and 4 miles southbound to demolish the Mulholland Drive bridge. This pass is one of the main links between Los Angeles and the Valley, especially to and from Los Angeles International Airport. Just how bad the traffic will get is up for speculation. Some estimates are up to 70 miles of backups. 200 extra firefighters are being brought on in the area, and four hospitals are putting up doctors and nurses in nearby hotels due to the traffic chaos that is expected.