The Link21 Program and its partner agencies aim to connect the BART and Regional Rail (including commuter, intercity, and high-speed rail) network in Northern California, as envisioned by the California State Rail Plan. The Program’s main goal is to transform the passenger rail network serving the 21-county Northern California Megaregion, which includes the greater San Francisco Bay Area, the Monterey Bay area, the Sacramento area and the Northern San Joaquin Valley. Acumen is providing planning and engineering services on the Arup/WSP team for the Link21 Program’s New Transbay Rail Crossing between Oakland and San Francisco that will reduce traffic and pollution in Northern California.