Complex sentence: The Shipyard Railway was built and operated by the Key System, a local transit company in the East Bay of the San Francisco Bay Area, which also provided commuter rail service between San Francisco and the East Bay over the Bay Bridge.
Split into simpler sentences: The Shipyard Railway was built and operated by the Key System, a local transit company in the East Bay of the San Francisco Bay Area. The Key System also provided commuter rail service between San Francisco and the East Bay over the Bay Bridge.