San Francisco International Airport: Take BART’s Yellow Line toward Pittsburg/Bay Point–Antioch to Concord; it is the rare airport transfer here that does not require a car. Allow about 75–90 minutes and roughly $10–$12 one way. For North Concord/Martinez, stay on one more stop. A taxi or rideshare is only sensible with several people or a very late arrival: traffic can turn the 40-mile drive into a costly, two-hour slog.
Oakland International Airport: Use the BART airport connector to Coliseum, then BART toward Antioch/Pittsburg-Bay Point, transferring if required by the service pattern. Budget about 60–80 minutes and roughly $10–$15 total. It is slower than it looks on a map but avoids the Bay Bridge and Caldecott Tunnel traffic.
Buchanan Field Airport: This is Concord’s small local airport, useful only when limited scheduled service happens to match your trip, or for private aviation. It is about 10–15 minutes by taxi/rideshare from downtown Concord; do not expect a convenient rail link. Check the operating carrier’s current schedule before planning around it.
Martinez Amtrak station: For Capitol Corridor passengers, Martinez is the useful nearby intercity rail stop. It is roughly 20–30 minutes to central Concord by taxi/rideshare, depending on traffic; local County Connection buses can connect the areas but are a practical choice only if their timetable happens to fit. Do not confuse Martinez station with a walkable extension of Concord.