SEATTLE -- Semi-trucks and cars were once again moving along both lanes of Interstate 5 through Chehalis Friday, although it was very slow-going.

Hundreds of semi trucks got back on the road Thursday evening after a costly three days of delay caused by torrential rain storms. Then, just before noon on Friday, authorities began allowing passenger cars to flow through as well.

 Slideshow: I-5 view from the windshield

 Slideshow: Aerial tour of Chehalis, Centralia, I-5

 More: See progress on I-5, Chehalis live cams

"WSDOT crews worked around the clock for four days to reopen a 20-mile stretch of I-5 that had been under nearly ten feet of water in places," said Alice Fiman, with WSDOT Communications.

Highway re-opened to truckers Thursday

WSDOT opened the highway to commercial trucks shortly after 5 p.m. Thursday. Later that evening, crews opened an 11-mile portion of southbound I-5 to all traffic. All vehicle types were allowed to enter the southbound lanes of I-5 at SR 6 in Chehalis (milepost 77) and continue south with no further closures.

Crews spent the rest of the night monitoring traffic, repositioning barriers and fixing guardrails.

Background: Storm in review

Friday morning WSDOT crews planned to begin replacing barriers that were shifted by swift flood waters on I-5 in Chehalis. Once the barriers are repositioned, two lanes in each direction on I-5 will be opened to all traffic.

Map: Detour route (pdf)

Speaking during a press conference Thursday morning, Washington Transportation Secretary Paula Hammond said that the flood damage to I-5 at Centralia was not as bad as feared.

Stan Suchan with the Transportation Department said some department vehicles and State Patrol cars were testing the roadway and it appeared that only a few inches of water were left on most of the asphalt.

 More: Flood recovery in Oregon

ALL storm slideshows

ALL storm video

The freeway has been closed since Monday afternoon because of the flooding Chehalis River.

About one mile of the interstate was submerged under water during the peak of the storm. WSDOT said more than 100 feet of pavement was damaged around the West Street overpass in Chehalis.

 Video: Water 10 feet deep on I-5

Amtrak passenger train service between Eugene and Vancouver, British Columbia resumed Thursday, with minor delays.

 Background: Floodwaters have blocked I-5 before

Washington Governor Christine Gregoire said the storm and flooding that hit Western Washington this week were unprecedented in many ways. She says flooding hit record levels on the Chehalis, Skokomish and Elwha rivers. She compared the windblown trees she saw to her recollection of the damage from Mount St. Helens.

Gregoire will lead another tour of storm damage Saturday with Senators Patty Murray and Maria Cantwell and U.S. Rep. Norm Dicks to enlist their help in congressional aid.