Track Signals

[CShaveRR]

I looked at the street view along Route 34.  The pictures are too blurry for me to decide whether these are searchlight signals or not.  But the appearance of some of these signals being "out" (say "dark" to a railroader) might be due to their extremely sharp directional focus.

From your original post, it sounds like the train is on both sides of one set of signals--of course those will be red-over-red, since the track is occupied on either side.  I could see only one set of signals in the shot of Somonauk, but there would have had to be others somewhere by the east end of the crossover pair.

These are "control point" signals (which I'm told is now the correct term for "home signals").  There, the aspects you're likely to see are:

Red/red:  stop (and stay).
Green/red:  clear down the straight route.
Red/green:  clear beyond the crossover, which you'll be using to go to the other track ("Diverging Clear").

The red/yellow signal you saw is just a variation on the red/green, showing that your train will be diverging through the crossover, and that the next signal you'll encounter will be red (stop and stay if it's a control point signal, and stop and proceed if it's not).  This was a "Diverging Approach" aspect.  Yellow-over-red would be an "approach" signal, telling you that the next signal will be stop or stop and proceed.

As others have suggested, so much depends on exactly which signals you're talking about.  If they have a number plate below the lights, they're intermediate signals, and the red becomes "stop and proceed" (or, in the case of most railroads nowadays, proceed at restricted speed without stopping).  

If you're still confused (or newly confused), you're not alone.  In spite of the fact that some railroaders are supposed to know all of this, it still can cause confusion, because the nuances might be different between railroads, up to the point where some signals can mean one thing on one railroad and a different thing on another.  And that has been known to cause some serious problems!

[cv_acr]

Probably looking at "Searchlight" signals which only have a single lens, which can be changed between different colours instead of separate lights for each colour. Absolutely one or more of those lights will be able to change to a different colour other than red.

[MikeF90]

I'm not a rail so I'll defer to the more expert. The reference for BNSF I have says:

Red over Yellow = Diverging Approach, reduce speed to 30 mph

Red over Green = Diverging Clear

Red over Red = Stop and proceed at restricted speed

power58

In Somonauk There are crossovers for both tracks, the signals at the East bound entrance are Red/Red track 2 and Red/Red track 1 and on the exit of the crossovers looking West bound the same signal set up is used there are no green or yellow light in these signals, they seem to be on or off.

Hmm, perhaps these are hold signals?

BTW Somonauk, IL is on the BNSF Mendota sub, 2MT CTC territory. Don't know of any others. To the OP, is this the one? https://goo.gl/maps/PMKji

[mudchicken]

He's nor saying if its TCS or ABS or what signals have number plates - Needs to break out his GCOR rulebook and timetable.

(Sounds like he is on BNSF's ex-CB&Q Mendota Sub which is mostly CTC/TCS somewhere around Sandwich/Somonauk.)

[Mookie]

Amateur guess:  constant red, no other colors - may be approach signals. Just what it sounds like.  Red/green - go for now, but next signal may be a stop.  Someone will pick this up and give you chapter and verse on it, but for now - I think this is pretty close. 

[power58]

A 2 Track BNSF has 2 signal lights on each track East bound and another set behind for West bound traffic. Last night a coal train was parked half way between the signals (Track 2) with the lead Loco east bound. If I looked back from the loco (West Bound) the Track 2 signals were Red/Red and the Track 1 signals were Red/Yellow. Coming the other way looking East bound the signals were Red/Red Track 2 and Red/Green track 1. In Somonauk There are crossovers for both tracks, the signals at the East bound entrance are Red/Red track 2 and Red/Red track 1 and on the exit of the crossovers looking West bound the same signal set up is used there are no green or yellow light in these signals, they seem to be on or off. Just wondering how to read the signals. Thanks.