Bus wiring is wires run parallel to the track with short feeder connections. This method is not recommended for DCS. Divide your loops into power blocks by inserting insulating pins in the center rail. Four power districts per loop would probably be adequate. Connect a pair of wires near the insulator pin, not in the center of the power district. Run all wires back to your power source. This is Star wiring. You can connect all wires to a distribution terminal block. Use at least #16 AWG. Many recommend #14 AWG.
It's also highly recommended to jumper the 2 outside rails together at each power connection.
Why is bus wiring not recommended for DCS? I did the star arrangement on my last layout but did not have insulator pins installed in the layout except at turnouts.