You take the AirBART shuttle from the airport to BART and BART to the Powell station and then walk to Union Square.
Depending on traffic, a taxi will cost from $40 to $50. This estimate does not include the customary 15% tip.The subway system (BART) is relatively safe, cheap, and famously punctual. Although the recent shooting of a rowdy - but unarmed - African American passenger by transit police has tarnished the agency s reputation somewhat. The Powell Street station is right next to Union Square. And most hotels in the area are a short walk away. Though I don t recommend taking the train if you have a lot of luggage, since BART stations aren t exactly designed for it. And as in any large city, passengers aren t particularly useful when it comes to helping strangers. The fare for the bus from the Airport Terminal to Oakland Coliseum station is $3.00. Bus drivers do not provide change, so make sure you have at least a couple one-dollar bills ready. The train to Powell Street itself will cost an additional $3.80. Unlike the airport bus drivers, BART s automated ticket machines will provide change.
From OAK- a shuttle, taxi or bus to Coliseum bart (Oakland) take any trains to San Francisco or Daly City, get off from Powell bart. It should be about $3-4 one way.Hope this help.. if not go to www.bart.gov
At Oakland Airport, look for the AirBART shuttle. It takes you to the Oakland BART station. From there, you take the BART train to Powell Street, which is next to Union Square.
Take the BART its cheap and safe