A 16km section of one of the busiest highways in the United States is closed this weekend in what people are calling 'car-maggedon'.
Interstate 405 in Los Angeles closed at midnight in Friday.
Work crews have 53 hours to remove the Mulholland Bridge before the morning rush hour begins.
The BBC reports the replacement of the 50-year-old bridge is part of a $US1 billion project. More lanes are being added to the freeway.
City officials have been warning Southern California residents for weeks about the potential for a traffic jam of epic proportions.
Los Angeles mayor Antonio Villaraigosa has told drivers to stay at home while the work's going on.
AFP news agency reports the contractor is threatened with fines of $US72,000 per hour if the work is not finished by 5am on Monday.
Interstate 405 carries about 500,000 vehicles on a typical weekend, through western Los Angeles and over the Sepulveda Pass into the San Fernando Valley.