The California Transportation Commission has approved the Port of Long Beach’s plans to replace the Gerald Desmond Bridge, clearing the way for Caltrans and the port to seek firms to design and construct the $950 million span.

The commission’s decision on Thursday is the final governmental clearance needed for the project. The port on Friday plans to issue a solicitation for design-build firms to bid on the job. Final design and preliminary construction are scheduled to begin in early next year, and construction of the main bridge supports could start in 2012.

The 42-year-old bridge is part of a heavily used commuter route and is used to transport cargo to and from the port. Port officials estimate it carries about 15 percent of the nation’s containerized goods.

The new bridge, which will be built alongside the existing structure, will feature a wider roadway. The project is estimated to create an average of 4,000 construction jobs per year during the five-year building period.

“The new bridge will be an iconic structure for Long Beach that modernizes the Port and puts thousands of people to work over the five-year building period,” Long Beach Mayor Bob Foster said in a statement. “It is precisely the right project at the right time for California.”

Of the $950 million needed for the bridge, $500 million will come from state highway and transportation bond funds. Federal sources are expected to contribute about $300 million. The port has pledged $114 million and Los Angeles County’s Metropolitan Transportation Authority is providing $28 million.