Timeline of the I-280 closure this weekend in San Francisco

SAN FRANCISCO (KGO) -- Starting at 9 p.m. Wednesday, Caltrans will close part of Interstate 280 in San Francisco for the entire holiday weekend.

Northbound 280 will shut down from the 101 split all the way into the city. The roadway won't reopen until Monday 5 a.m.

"Here's a lot of preplanning that took place. We know what this contract schedule is, we have an hour-by-hour schedule," Caltrans spokesperson Andrew Yan said.

Map of road closure along I-280 in San Francisco

The first step is to close the freeway. The CHP has brought in extra officers for that.

"It definitely is a large project and a large undertaking. Any time you shut down a freeway it's going to be a large undertaking," CHP Ofc. Mike Ferguson said.

Equally large will be the job of lifting up the freeway ever so slightly to take all the weight off the crumbling concrete hinge they're about to demolish.

"The contract has hydraulic jacks that are placed underneath the structure, the falsework, and they will actually jack up the falsework underneath the structure at the appropriate time," Yan said.

Then come the jackhammers. Demolition could take 10 hours, maybe less. Then, the slow part will be building a new hinge out of concrete and rebar -- one that's three times as long as the old one.

"Putting in the new rebar, connecting the new rebar to the existing rebar of the structure, and that takes some time," Yan said.

This is the second of four hinges Caltrans needs to replace. They're joints that let the freeway flex with traffic and earthquakes. There are dozens of them, but there are only four of them falling apart at this time. They've planned each fix for a different holiday weekend. That eases the traffic, but doesn't eliminate it.

"Just judging from last closure, that we had in the southbound direction, the city streets as well as 101 freeway was backed up significantly," Ferguson said.

With such an impact on drivers, Caltrans often pays incentives to contractors for finishing early. Not this time.

"There isn't any incentive for the contractor to finish early, although there is disincentives, penalties for opening up the freeway structure late," Yan said.

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