SACRAMENTO, Calif. -- Southbound Interstate 5 traffic coming into downtown Sacramento from the Natomas area was tangled for at least two miles during Wednesday morning's commute as a major road construction project continued.

Southbound lanes of I-5 are shut down from Richards Boulevard south to the Highway 50 interchange as crews repave a stretch of freeway known as the boat section. The six-week project began on May 30 and is the biggest road repair effort the capital has seen in decades.

Wednesday's southbound backup stretched from the junction of I-5 and Interstate 80 south to Richards Boulevard. Southbound freeway traffic must exit at Richards Boulevard or J Street.

The southbound lanes of I-5 were shut down starting last Friday for construction. The commutes on Monday and Tuesday were relatively mild compared to Wednesday's backup.

The northbound lanes of the freeway are open and traffic was flowing well.

As the project continues, the southbound and northbound lanes are being shut down in the downtown area at various times.

The project was launched to repair parts of the roadway damaged by years of water seepage from the nearby Sacramento River.