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. The segment of TANC's 500 kV line from the Sacramento River crossing south to the Tracy Substation has delta pylons like those found on the Captain Jack-Olinda segment, although they are slightly different. This is because south of the Sacramento River crossing, the original 230 kV line paralleled the two PG&E 500 kV lines almost all the way to Tracy Substation. In order to meet separation requirements, a new alignment for the 500 kV line had to be built some distance to the east, with the exception of the San Joaquin River crossing, which utilizes the former 230 kV facilities. This alignment can be seen from Highway 4 and the western part of the San Joaquin River portion of the Sacramento River Delta. A portion of the former 230-kV line south of the Sacramento River remains in service today as part of the 69 kV system that serves the pumping stations on the Contra Costa Canal.