Spokesman Travis Phelps said the framework is in place and workers are tightening bolts and welding sections on the temporary structure that's 24 feet wide and 160 feet long.
He said they'll be installing panels Monday that will be paved with asphalt to form the new bridge deck.
Some other work remains, such as divers' inspecting piers, so the department isn't saying yet what day the Mount Vernon bridge will reopen.
Traffic has been detoured since May 23 when a truck with and oversize load struck the 58-year-old span, causing it to crumble. The bridge carried 71,000 vehicles a day.
More Northwest Headlines
E. coli tied to Costco more dangerous than Chipotle outbreak Thousands in Washington to spend Thanksgiving in dark, cold Student leader: Washington college unsafe for women of color Court revives Oregon suit over ‘phantom recall’ of Motrin New wolf pack appears in Okanogan County Environmental review: Vancouver oil-by-rail terminal could hurt fish Spokane commission supportings bringing refugees Worker cut from 1 job after article about 80-hour schedule
Our new comment system is not supported in IE 7. Please upgrade your browser here.