Metro’s Blue and Expo Lines approach their terminus in Downtown Los Angeles via at-grade tracks through the South Park neighborhood.  For a quarter-century, those tracks have been flanked by an assortment of surface parking lots and industrial buildings.  Not for much longer. Yesterday, plans were filed with the City of Los Angeles to replace four small warehouses at 1370-1418 S. Flower Street with a mixed-use development.  According to a case filing from the Department of City Planning, the proposed seven-story development would feature 147 apartments on its upper floors.  At ground level, plans call for either 6,741 square feet of retail and restaurant space, or a combination of five live-work units and approximately 1,200 square feet of commercial space. Additional details are currently unavailable through city records. The .69-acre project site lies almost directly across the street from the Avant apartments, a similar seven-story complex which opened in phases between 2014 and 2016.  A similar development is now under construction at 1400 S. Figueroa Street.