Operating along the UP Coast Subdivision (Between Gilroy and Santa Clara-Univ) and its own Peninsula Subdivision (Santa Clara-Univ to San Francisco), Caltrain runs between Gilroy, with 28 intermediate stops until it's destination in San Francisco. Caltrain operates all day everyday. This system is most busy between San Jose and San Francisco with approximately 50 trains in each direction on a weekday. With connections to Capitol Corridor and ACE at San Jose and Santa Clara-University, one can easily take an all-railroad journey from Peninsula to the East Bay or Tri-Valley and Central Valley. Other transfer stations include San Jose Diridon (VTA), Mountain View (VTA), Millbrae and San Bruno (BART), and 22nd street and San Francisco (MUNI). BART offers an SFO (San Francisco International Airport) shuttle train from Millbrae, and SJC (San Jose Norman Y Mineta International Airport) is also accessible by Caltrain via the Santa Clara-University station. Numerous stadiums and parks are accessible by Caltrain trains, including the SAP Center in San Jose, Levi's Stadium, Stanford University, Chase Stadium, and Oracle Park. As of right now, this is the only heavy-rail line serving the Peninsula, and is currently undergoing heavy modernization (CalMod) to accommodate new, environmentally friendly electric trains to replace their diesel fleet.