The closure will give work crews 20 hours to tear down an old connector-road overpass that, until recently, linked the southbound 405 with the eastbound 22.
A high-traffic section of I-405 will shut down Saturday night, and transportation officials have one word for those thinking of braving the detours and delays: Don’t.
The freeway is scheduled to close in both directions near its junction with the 22 freeway from 9 p.m. Saturday until 5 p.m. Sunday. The best detours available will send drivers on long side-street tours of cities such as Los Alamitos and Seal Beach.
And traffic on those side streets could be heavy. The stretch of I-405 that will be shut down sees more traffic on any given day than any other freeway segment in California, according to Caltrans numbers. It’s busier than any point on Los Angeles’ notorious “Carmageddon” closure in 2011.
“If you can possibly avoid the area this weekend, that would probably be your best choice,” said Darrell Johnson, the chief executive of the Orange County Transportation Authority.
The closure will give work crews 20 hours to tear down an old connector-road overpass that, until recently, linked the southbound 405 with the eastbound 22. A new connector opened last month as part of a larger project to better link carpool lanes on I-405, I-605 and the 22.
The old overpass, though, is unlike anything demolished in California before, said John Zehnder, senior bridge engineer with Caltrans.
It gets its strength from a series of cables hidden inside its structure, each two inches across and loaded with a million pounds of tension, Zehnder said. In most bridges, those cables are encased in cement – but not in this one.
That means the cables could whip back when workers cut them to break apart the bridge. The demolition crew has taken the unusual step of leaving the bridge deck in place – rather than breaking it up early to get a jump on the closure clock – to help contain those cables when they snap.
Caltrans plans to grind up and recycle the old concrete and steel of the bridge. It also plans to use the closure as an opportunity to perform what it calls “swarm maintenance” on that part of the 405, sealing cracks, sweeping up litter and killing weeds.