Bay Area Rapid Transit using Google Maps API Premier v3 to power searches and biking directions on BART.gov. It serves San Francisco Bay Area covering 4 counties, 43 stations, 104 miles (167 km) of track, and has an average weekday ridership of 335,000 passengers. It's the 5th busiest heavy rail rapid transit system in the U.S. BART's QuickPlanner, provide some cool new trip planning services, including bicycle directions and station area points of interest, using Google Maps API.
"using Maps API, we're able to provide information about points of interest near BART stations, including directions. If you visit neighborhood map section, use freeform search for station area destinations, and we're no longer limiting you to searches based on standard address formats or a preset pull down menu. We also use Maps API for services like "Find Closest Station" and map images presented on station landing pages," says Timothy Moore.
More Info: BART QuickPlanner