Ghilotti Construction of Santa Rosa was the low bidder on work to replace the Airport Boulevard overpass on Highway 101, which should be completed in two years, transportation officials said Wednesday.

Ghilotti bid $28.7 million, which is $600,000 more than the Caltrans engineers had estimated, said Suzanne Smith, executive director of the Sonoma County Transportation Authority.

The Airport Boulevard interchange has become a choke point on the freeway, with traffic backing up onto the freeway during the morning commute.

The work will include a new overpass and ramps. It will also include the permanent closure of the ramps at Fulton Road.

The contract is expected to be awarded in a month and the work is expected to be completed in late 2014, Smith said.