signals for dummies

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Second, I have a mainline with a turnout that accesses a through passenger station track.  Again, when staying on the main, a basic clear signal seems appropriate, but what about when trains are to enter the passenger station?  I can find various rules that apply to red over yellow or yellow over yellow that seem to make sense as they reference slow speed and prepare to stop, but nothing specific to a station or through siding.

Marty:
I'll attempt to explain the second situation.  True, if the turnout is lined for main track
movement (and there are no trains, rail defects, or switches not properly lined) for
the next two blocks, the signal will display CLEAR (or green).  Bear in mind that on
CPLs, green is only used to display CLEAR.   The red-over-yellow (known as
RESTRICTING) discloses one thing in particular -- the rails aren't bonded.  That
means there could be a train on the siding and the signal won't indicate it. So it becomes
the responsibility of the crew not to exceed 15 mph and to have the ability to stop
within half the range of vision, and looking out for turnouts not properly lined.   Probably
one example of failing to comply with the RESTRICTING indication happened on the
Union Pacific in the Mohave Desert.  UP's sidings weren't bonded, so the best signal
a train entering the siding could get was RESTRICTING.  On one of these sidings,
a work train had stored its train on a branch diverting from the passing siding, but failed
to re-line the turnout for passing track movement.  A train entered the passing siding at
restricted speed, then entered the track  holding the work train and collided.
Guess who got blamed.

The yellow-over-yellow (known as an ADVANCE APPROACH), is used to give 
sufficient notice that the 2nd signal ahead displays STOP.  It has application especially
on descending grades and short blocks.            Harry Bundy   
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