Auburn, Placer County -- State officials are celebrating the imminent completion of what is being billed as the biggest freeway renovation project in California in years.

Crews are putting the final touches on the $820 million, 15-year effort to revamp Interstate 80 starting about 30 miles northeast of Sacramento to the Nevada state line, 423 miles worth of lanes, the Sacramento Bee reported. The road crosses the Sierra and is a major truck route in addition to carrying vacationers headed to Lake Tahoe.

Dignitaries posed for pictures and lit a symbolic Olympic torch at a celebratory gathering for the project Wednesday. The original road was built between 1957 and 1964, and state officials timed the completion of the Sacramento-to-Truckee leg for the 1960 Winter Olympics at Squaw Valley, the Bee reported.

The renovation is in fact a series of projects that began in the late 1990s after officials determined the freeway had outlived its functional life. The high mountain sections of the freeway, in particular, were gouged where trucks and cars had passed with snow chains.

In some cases, the entire freeway was removed and replaced. In other spots, a new slab of concrete was put on top.

"These 15 projects have brought I-80 back to its original glory while updating it to modern standards," said Rick Land, a California Department of Transportation chief deputy director.

The new freeway is expected to have a longer life. Concrete slabs put down in key high-mountain sections are thicker, giving crews extra inches to grind down when the road becomes rutted. And slabs of different lengths are expected to cut down on the damaging up-and-down movement of trucks as they cross from one slab to another, said David Catania, Caltrans construction manager.

Funding for the project came from the state and federal governments and California voter-approved bonds.