Part of a freeway overpass under construction fell onto the northbound lanes of the Harbor Freeway early Monday evening, causing a massive traffic jam but no injuries, authorities said.
Officials said they expect the northbound Harbor Freeway lanes to remain closed until the early morning hours. The southbound lanes were open, but traffic was moving slowly.
The overpass, part of the Century Freeway construction, crosses over the Harbor Freeway between Imperial Highway and El Segundo Boulevard. It apparently "shifted on its base" about 6:30 p.m., a dispatcher at the California Department of Transportation said.
"A girder slipped and dislodged a few pieces of lumber," a Caltrans source said. "That's all that fell on the freeway."
The cause of the slippage was under investigation by Caltrans, and crews were on the scene attempting to repair the damage. The earliest Caltrans estimate for the lanes to reopen was 4 a.m.
Due to safety precautions and the need to get heavy equipment on the scene, however, all northbound lanes of the Harbor Freeway were closed from Redondo Beach Boulevard to El Segundo Boulevard.
California Highway Patrol officers rerouted hundreds of cars off the freeway onto surface streets, a spokeswoman said. Officials recommended that motorists take alternate routes north, such as the San Diego Freeway, the Long Beach Freeway or the San Gabriel River Freeway.
Heavy congestion was reported in all lanes of the freeway from the harbor area north to downtown Los Angeles.
"It's a mess out there," said CHP spokeswoman Lujuanna Lopez.