Enough Power Supply

Not sure how many a "handful" of engines is, but I think a PH180 can handle 3 or so without too much issue.  What you need to keep in mind are the other power requirements such as passenger car lighting (non-LED lights take a lot of power), smoke units, lights, etc.  If you are running separate loops, powering each loop with its own transformer would be better but more expensive.

Personally I would get a separate transformer, like a Z-1000, to run the accessories. Get a cheap Z-500 brick or a wall wart to power the TIU, and if it is practical power the switches from the accessory transformer.

I'd probably consider a couple of power districts and add an additional PH180.  I like the idea of a separate accessory transformer as well.

Other than their lamps, track switches don't need to be added in to the calculations, since they only operate intermittently and (generally) one at a time.

If you have switches with 2 lit lamps at all times (one on switch, one on controller) that can be quite a burden - almost 2 Watts per switch.  So with 19 switches, that's over 30 Watts which is quite a tax on a 180 Watt supply.

I have never seen a comprehensive study of power requirements for engines and accessories for O-gauge.  A DCS engine at idle may draw up to, say, 5 Watts.  Pulling nothing and meandering along at 10 sMPH on straight section an engine might draw 15 Watts.  Pull a few cars around a tight curve and you're at 30 Watts.  Add a few more cars and climb a grade and you're at 50 Watts.  Turn on smoke and add another 5 Watts.  A lighted passenger car - another 5 Watts per car (unless converted to LED). 

Accessories can add up.  There was a recent thread about some new Menards lighted buildings using LEDs (a lot of them); even with LED technology the building requires over 10 Watts!  That same building using incandescent bulbs would need, say, 50 Watts to provide the same brightness.  Yikes! 

Your DCS/TIU box requires less than 5 Watts.  But with 19 switches, I see a DCS/AIU in your future.   The AIU switch controller is powered by the TIU.  So add a few more Watts.

As the guys above suggest, get another transformer, wall-wart, whatever to power anything that is not rolling. 

Most accessories operate on DC or AC voltage.  The DCS/TIU can be externally powered by DC or AC.  To the extent you can use DC, you will find DC power costs about 10 cents per Watt whilst AC power costs 5-10 times that.

Its all about V=IR... eliminate as MUCH resistance as you can

In all honesty, the big AMP gobblers are the smoke units and those darn K line aluminum lighted cars! But they  look soooo cool!

    Seldom do folks complain about having too much power.

     I'd treat the track as one thing and address its needs accordingly when the time comes. Splits into blocks later aren't hard imo; I just slice the center rail pin with a dremel (tube track). But I'd run as much seperately as possible. If for no other reason, so that everything doesn't flicker when turnouts, and accessories activate.

Thanks for all the input everyone!!  IT's a HUGE help!

The only reason I was wondering was because I'm actually using plans from the Atlas-O 3-Rail Layouts Book.  It has 2 Atlas 80 Watt Transformers for the whole setup.  Obviously that doesn't include accessories, but I'm sure it'w meant to run at least 2-3 trains at one time.  According to this setup, I'll have 20 more watts than needed.. Plus I do have a Z-500 which I believe is 54 Watts.  I was planning on using that for all the lit accessories.  

I got a DCS/TIU setup.. I have the PH-180 hooked to the FIXED Voltage IN.  The FIXED Voltage OUT goes to a 12-port terminal block, which goes to the power drops.

Running three locomotives with smoke and perhaps a lighted passenger train will be pushing the limits for the 180W of power regardless of what Atlas was showing in their plan.  I'd want more power on an 8x21 layout.  Mine will be around 12x22 when we move, and I'll have probably three or possibly four PH180's powering it.

So do I understand, a separate power supply is wired to each insulated block? How is this related to the TIU and the signal?

Wally