Which signal arrangement is correct? (ATSF)

[Southwest Chief]

I'm installing a cantilever signal on my HO layout.  I'd like to know which of the two prototype images below would be the correct searchlight signal target placement for my layout:

Prototype 1 (low mounted single target)

(Note: I edited out the right upper signal target)

Prototype 2 (high mounted single target)

Here is a super crude drawing of my track setup.  Two main tracks.  Call left track main 2 and right track main 1.  A spur comes off main 2:

Looks like this:

Which of the two signal arrangements shown above is correct for my track? 

The left targets for main 2 is easy...two signal targets because of the switch.  But what about the single target for main 1 on the right?  Should I mount the single target low (like prototype photo 1) or high (like prototype 2)?

[Train Modeler]

I am starting to study signaling myself.    The timeframe of your layout may have an impact on the signaling and even possibly the location as things have changed over time.  

I really like the nmra and so here's a link to some good info tha may help.

http://www.nmra.org/sigs/railway-signaling-technical-and-historical-society

Richard

[steemtrayn]

The signal on the left would require two targets because there is a switch involved, and a diverting train would need to slow down to negotiate the switch. The  maximum speed would be determined by the sharpness of the curve (frog angle) of the switch, and and the signal indication would require more than one target. There are no switches involved on the right hand track, so all necessary indications can be covered with one target ...Green=clear, Flashing yellow=Advance approach, Yellow=Approach, Red=Stop and Proceed. There could be other factors involved, such as the switck being hand thrown, or is it part of an interlocking? I'm not familiar with the rules on your railroad, but this is how it's usually done in New Jersey.

[steemtrayn]

Oh, I forgot...Since only one target is needed on the right hand track, it can be mounted low, no need to go any higher.

[Southwest Chief]

Thanks.

I've been wondering why that prototype target is mounted high. Maybe there was a lower target that was removed at some point.  Or visibilty required it to be mounted high.

I found a prototype ATSF cantilever with a double target and single target similar to my setup.  Single target mounted low: