SACRAMENTO (AP) — Repairs starting today at the convergence of three major freeways in Northern California could cause massive traffic delays for vehicles passing through the state capital.

California Highway Patrol Officer Mike Bradley says hour-long delays are possible on Highway 50 through Sacramento, which links the capital to South Lake Tahoe. Officials are urging residents to use alternate routes and mass transit to reduce traffic on the section under construction.

Backups could spill onto Highway 99 and Interstate 5, which are California’s major north-south thoroughfares and border the construction zone, as well as the “Business 80” connection to Interstate 80.

“We anticipate there will be delays, but we can’t anticipate the impact at this point until we get into it,” Bradley said. “It’s going to have significant impact on numerous roadways.”

The $46 million construction project is on an elevated portion of Highway 50 in downtown Sacramento and is overseen by the California Department of Transportation. It is expected to last through June, with a five-day break for the Memorial Day weekend.

Around-the-clock construction is planned on eastbound Highway 50 until May 21 then on westbound lanes from May 27 through June 25. About 250,000 vehicles a day use that section of highway, which has caused extensive wear and cracking, according to Caltrans. The contractor, Myers & Sons Construction of Sacramento, will install a four-inch concrete deck on top of the existing surface.

No lanes will be added, but the construction will strengthen the elevated lanes against earthquakes and widen the highway’s shoulders. Concrete barriers, railings and energy-efficient lighting also will be added, according to Caltrans.

The worst traffic tie-ups are expected as construction begins and before Sacramento residents figure out new ways around it. Interstate 5 and highways 99 and 50 also are major commuter routes that connect the capital with his outlying neighborhoods and suburbs.

The half-mile section of freeway is known as the W/X Viaduct, so named because it is situated above and between W and X streets just south of downtown.

Sacramento-area residents have been warned about the potential delays, but Bradley said long-distance travelers might be caught by surprise. There are so many possible alternate highways and surface streets that the CHP and Caltrans are not posting detours, leaving it to motorists to find their own way around the construction.

Motorists can check http://fix50.com , follow @fix_50 on Twitter or call 800-427-ROAD (7623).

Bradley also recommended that people traveling through Sacramento bring a GPS unit and become familiar with its “detour button.”