Paul,
I think what you are thinking about are "Terminal Blocks":
or larger like this one:
Your "main bus" would be the wires going from the controller/power source to the terminal block main POS and NEG terminals (possibly centrally located beneath the layout) and all track power would then run from the terminal block to the various points of the track plan.
With a layout the size of yours, the only benefit to this method I see is it removes the need to solder or join your feeders physically to the main bus wire, and that could be a good thing if your not that keen on soldering or climbing under your layout.
The biggest issue I see is the addition of something that could fail resulting in the loss of power to the entire layout. I'm not saying the terminal block will fail as I have had mine for years without an issue. That being said, I only use mine for my accessories not for track power.
Although time consuming and a task, I honestly think you would be better of running a single main bus around the layout beneath the track and just join your feeders to it as needed.
Anyway, hope the terminal blocks are what you were after, if there is something else, hopefully someone will direct you that way.
As said, what you propose will work without a doubt, just not sure if it is the best option for your layout.