 In addition, the tower's design is strikingly different from the lighter and wider PG&E tower, and the design also changes significantly as one goes from north to south on WAPA's 500 kV line.The TANC line changes design at the Olinda substation from the delta pylon pictured at the Interstate 5 crossing to the two-level pylon pictured above.This is because much of the segment between the Olinda and Tracy substations was constructed by upgrading an existing double-circuit 230 kV line.