Remember the "Big Fix?" Fasten your seat belts for the "Big Switch."
Tens of thousands of Sacramento drivers, who were sent scattering five years ago when Caltrans shut Interstate 5 for repair, will soon face a freeway fix that could be even more intrusive.
Caltrans will close a section of the elevated W-X freeway through central Sacramento in each direction for two months next spring for major repairs.
Highway officials who call that freeway's bridge section the Camellia City Viaduct intend to keep some traffic flowing in each direction, though, by switching eastbound traffic onto some westbound lanes for a month, then reversing the switch the following month.
That means cars and trucks will be going in opposite directions on the same side of the freeway for a month at a time, separated by temporary barriers. Traffic in one direction will be squeezed into two lanes, the other direction into three lanes.
The construction zone will run from 14th to 26th streets, and officials warn that the resulting bottleneck could cause major traffic jams and a ripple effect on freeways for miles.
The W-X, so called because it runs between and parallel to W and X streets, acts as the hub of the region's freeway system, collecting a quarter-million drivers daily from Sacramento's major commute freeways that funnel in from the north, south, east and west.
"Traffic impacts are going to be pretty extensive," project manager Rod Murphy said. "We expect impacts back toward El Dorado Hills on Highway 50 and on Highway 99 toward Elk Grove."
Project work is expected to start in August. The two major closures are planned for spring 2014. Caltrans officials said they will hire a public relations firm to get information out and help drivers figure out alternative routes.
Highway engineers said they thought about shutting down only one lane at a time so they could keep most of both sides of the freeway open throughout, but they decided that full directional closures will dramatically speed the construction.
The Caltrans plan includes building two temporary crossover sections in the center medians to switch traffic from one side of the freeway to the other. Those crossovers will be located on portions of the elevated freeway that sit on earthen berms.
To encourage the contractor to work quickly, agency officials said they will offer a $150,000 daily bonus up to maximum $1.5 million for every day less than a month each closure is in place.
The $46 million project may be the biggest fix ever on the busy crosstown freeway, which is 45 years old. Officials say inspections show the road surface on the elevated bridge section is cracking from years of traffic and water intrusion, and in need of a complete redo. Highway officials made a point of saying the freeway remains safe for travel.
Caltrans plans to add 4 inches of new road surface made out of concrete reinforced with shreds of steel. Caltrans officials say that will extend the freeway surface lifespan another 20 years.
The work includes widening all shoulders by 2.5 feet to meet modern width standards. Crews also will build new safety barriers on the viaduct's flanks. At the same time, Caltrans intends to reinforce an estimated 144 concrete bridge pillars with steel rods to make them more earthquake resistent.
Several ramps and connectors are expected to be closed at some point during the project. They include connectors to and from Highway 99, as well as the 10th and 16th street ramps. The state will publish detailed closure dates next year.
The project also will require some nighttime closures of surface streets under the freeway. Temporary forms will be built under the freeway, including a protective covering over the Union Pacific and light-rail train tracks that run under the freeway between 19th and 20th streets.
Based on Sacramento's experience during the Big Fix in 2008, officials said many commuters will avoid the freeway and wind through city streets instead, causing intermittent street congestion.
Overall, Caltrans officials said they were pleased with the public's response to the I-5 freeway closure five years ago, and said they expect the public to make similar accommodations this time.
Murphy said Caltrans will ask the governor to agree to allow some state workers to work from home and others to work flex schedules. The agency will encourage drivers to use transit or bike to work.
Caltrans is expected to launch the bid process for a contractor in the next few weeks, and choose a contractor this summer.
Call The Bee's Tony Bizjak, (916) 321-1059. Follow him on Twitter @tonybizjak.