BART is gearing up plans to relocate its Police Department to new headquarters in downtown Oakland in 2026, after receiving a $150 million federal loan to fund construction.  BART police are vacating their current headquarters at 800 Madison St. in Oakland to make room for a new BART development project, which will include affordable housing units, shops and parking. The new headquarters will be about a mile away, at 2000 Broadway.  In a competitive market, the new facility could help…