Noting that the project has been discussed for more than 20 years, BART board president James Fang said, "We had to face many challenges to get here today."
More than 100 people attended this morning's ceremony at the Coliseum station, including U.S. Rep. Barbara Lee, D-Oakland.
Lee said the beginning of work on the $484 million project "is the result of decades of preparation."
She said that at a time when Oakland's unemployment rate is more than 17 percent, the project is expected to create between 2,500 and 5,000 direct and indirect jobs during its 3.5-year construction phase.
Oakland Mayor Ron Dellums said the project is "a triple win" because it will make the Oakland airport more competitive, create jobs and help the environment by making it easier for people to get to the airport without using their cars.