Design for signals, leave them for last

Incorporate signals into your design, so you'll know where they're going and you can plan a signal bus and all that, but then leave them for the last so that messing with them doesn't get in the way of building/running your layout.

Signals?

It all depends on what you want to do with them and what operating method you want.

If you want full blown CTC then by all means install signals.

If the signals are for interlockings, then by all means install signals.

If the signals are purely switch position indicators and are not truly ABS, then go for the gusto.

If the signals are purely scenic to provide pretty colored lights, then knock yourself out.

If the signals are for ABS, then you might want to consider your options.  The primary purpose of ABS signals is to:

1. prevent trains from overrunning the train ahead at speed
2. protect trains from switches lined against them
3. protect them from running over a broken rail at speed
4. provide warnings that a train will be overrunning its authority. 

On a model railroad #1 is not very necessary since most operator can see well ahead of the train and can get stopped prior to a train ahead.  #2 is useful on a model railroad if the operators aren't diligent about restoring switches or the crews aren't diligent about watching where they are going.  #3 isn't applicable to model railroads.  #4 would be useful for a model railroads if the crews aren't diligent about staying within their authority.

So it boils down to what do you want the signals to do and how much you want to spend doing it.  I maintain you can just pretend there is an ABS signal system in place (and pick up any rules benefit which may accrue if you are using TWC or DTC) and operate the layout without it.   All operating without ABS does is require the crews to pay attention to where they are going.

Signal!!!

I've always liked signals, so I added them.  They just add a certain 'something' to a layout.

I use them for APB running.  I didn't want to have a dispatcher, so CTC was out.  There's not enough traffic on my layout to justify it, plus I don't like that job, so didn't want to make anybody else have to do it.  What I've done allows trains to run on signal indication.  It's not truly prototypical because it would still need a dispatcher to set up meets and passes, but it's certainly adequate for model operations.

I didn't have DCC when I started building my layout, so I put them in after all the track was installed.  With Digitrax and JMRI, it was fairly easy to do. 

My suggestion is that, if you even THINK you want signals in the future, wire your layout appropriately.  It's a lot easier that way.

For reference, I went with Atlas G-type signals because Conrail had a lot of those across the system.

Kerry

right time to decide

You are asking the question at the right time, before the layout is built.

Our signals are mostly static, though a few are DCC controlled. After running on friends signaled layouts, the next build I am involved in will very likely include full signaling. Signals add much to a model railroad. 

I was in San Diego one day while my wife was in a class.

I spent the day at the San Diego Model Railroad Museum.  In the afternoon, one of the members took pity on me and asked me if I would like to run on Tehachapi?  He didn't need to ask twice.  That layout has signaling, and it is essential.  The hills are so big that you often can not see the train that is coming when you get a red signal.  If you run a signal, you may well have a "corn field meet".

Ops No Brainer...

It seems to me a signaling system would be a no-brainer.  Instead we have people LOOKING AHEAD for the next train.  Very prototypical indeed!!

Smoke signals

If they are looking ahead for an opposing train then they are running on restricted speed, are in yard limits or aren't using any form of main track authority at all.  If they are using TT&TO or track warrants or DTC or pretty much any other system then they won't be looking for an opposing train, they will be looking at their watch/clock and their authority.

If they are looking for a train ahead in the same direction, block signals won't stop that, at some point they will still be looking out for the train ahead.  Actually without signals, they shouldn't be looking out for the train ahead (its the train ahead's responsibility to look out for the train behind, i.e. flagging).  With signals the responsibility shifts to the following train to look out for the train ahead (restricted speed).