Western Railroad Discussion > Meaning of block signals?

I was driving up New Avenue from Lockport to Lemont, Illinois, which parallels the old GM&O line from Chicago to St. Louis, the other night and trying to explain the meaning of the block signals to my wife, and found that I didn't remember as much from my train-riding days as I thought I did. Green means it's OK to enter the block at maximum speed, red means don't enter the block, there's a train in it, and yellow means that this block is clear but there's a train in the next block, or so I remember. What does a flashing yellow mean? Also, this line has high and low signals; I recall that they refer to the current block and the next one, but which is which? I remember crews calling the upper one lit yellow as "high yellow;" what does that signal mean? Do they have different meanings on different railroads? (I can already guess the answer to that one.) Is there a good Web site that has a rundown on this?

There is no standard set of signal indications. Railroad practice varies. Flashing yellow could mean "advance approach", which means to approach the next signal prepared to find it set at "approach". Or it could mean something different, like for example a limited speed crossover (which might also be a flashing green).

The easier question is what the different signal heads do. The top signal is the one for the main route, so a "high green" is a clear signal on the straight route. A red over yellow or red over green means a diverging route has been set. If there are three heads, generally the middle one governs a moderate-speed route and the bottom one a slow-speed route. But practice varies.

Get an employee timetable for your favorite railroad. It will show and define signal indications.

I have heard flashing yellows called "come on" signals (on CNW). basically, an approach in anticipation of a clear, so train can keep momentum. sometimes a lunar indication.
am I right?

......were those still the old "B&O" type color position lights?(Remember the B&O controlled the old Alton, a GM&O predecessor, IIRC)......

Bob

ATSF100WEST......Out

ddkid Wrote:
-------------------------------------------------------
> red means don't enter the
> block, there's a train in it,

Sometimes red means stop and stay stopped. But with many signals it means stop and proceed at restricted speed.

> and yellow means that this block is clear but there's a train in
> the next block,

Yellow usually means be prepared to stop at the next signal.

> What does a flashing yellow mean?

Flashing yellow has several meanings but most of them boil down to the next signal is yellow.

--
http://www.spinics.net/rail/

When I drove the line this past summer UP was going great guns in replacing the B&O position lights with Safe-Trans color lights with safety cages. Ugh. They're upgrading the line to a 100-mph passenger corridor, I hear.

eeek Wrote:
-------------------------------------------------------
> ddkid Wrote:
> --------------------------------------------------
> -----
> > red means don't enter the
> > block, there's a train in it,
>
> Sometimes red means stop and stay stopped. But
> with many signals it means stop and proceed at
> restricted speed.

And on many roads it means proceed at restricted speed (without stopping).

>red means don't enter the block, there's a train in it, and yellow means that this block is >clear but there's a train in the next block,

Just a quick note: These signals protect much more than just train traffic. A red indication could also be a switch lined against the main, a broken rail, signal malfunction,etc.

Xingman
Updating http://home.internetcds.com/~xingman/ again!

Xingman Wrote:
-------------------------------------------------------
> >red means don't enter the block, there's a
> train in it, and yellow means that this block is
> >clear but there's a train in the next block,
>
> Just a quick note: These signals protect much
> more than just train traffic. A red indication
> could also be a switch lined against the main, a
> broken rail, signal malfunction,etc.
>
> Xingman
> Updating http://home.internetcds.com/~xingman/
> again!

And, something as simple as not restoring a derail to the proper position.

BNSF
BLOCK SIGNALS
==============
Rule: 9.1.3

Aspects of Color Light & Semaphore Signals:
Green
Green/Red
Green/Red/Red
Green/Dark
Green/Dark/Dark

Name:
Clear

Indication:
Proceed
------------------------
Rule: 9.1.4

Aspects of Color Light & Semaphore Signals:
Yellow/Flashing Green

Name:
Approach Limited

Indication:
Proceed prepared to pass next signal not exceeding 60 MPH and to advance on diverging route.
------------------------
Rule: 9.1.5

Aspects of Color Light & Semaphore Signals:
Yellow/Green
Yellow/Green/Red

Name:
Advance Approach

Indication:
Proceed prepared to pass next signal not exceeding 50 MPH and to advance on diverging route.
------------------------
Rule: 9.1.6

Aspects of Color Light & Semaphore Signals:
Flashing Yellow
Flashing Yellow/Red
Flashing Yellow/Red/Red
Flashing Yellow/Dark
Flashing Yellow/Dark/Dark
Yellow/Yellow
Yellow/Yellow/Red

Name:
Approach Medium

Indication:
Proceed prepared to pass next signal not exceeding 40 MPH and be prepared to enter diverging rout at prescribed speed.
------------------------
Rule: 9.1.7

Aspects of Color Light & Semaphore Signals:
Yellow/Lunar
Yellow/Lunar/Red

Name:
Approach Restricting

Indication:
Proceed prepared to pass next signal at restricted speed.
------------------------
Rule: 9.1.8

Aspects of Color Light & Semaphore Signals:
Yellow
Yellow/Red
Yellow/Red/Red
Yellow/Dark
Yellow/Dark/Dark
Yellow/Dark/Red
Dark/Yellow

Name:
Approach

Indication:
Proceed prepared to stop at next signal, trains exceeding 30 MPH immediately reduce to that speed.
------------------------
Rule: 9.1.9

Aspects of Color Light & Semaphore Signals:
Red/Green
Red/Green/Red
Red/Red/Green
Red/GreenDark

Name:
Diverging Clear

Indication:
Proceed on diverging route not exceeding prescribed speed through turnout.
------------------------
Rule: 9.1.10

Aspects of Color Light & Semaphore Signals:
Red/Yellow/Yellow

Name:
Diverging Approach Diverging

Indication:
Proceed on diverging route not exceeding prescribed speed through turnout prepared to advance on diverging route at the next signal not exceeding prescribed speed through turnout.
------------------------
Rule: 9.1.11

Aspects of Color Light & Semaphore Signals:
Red/Flashing Yellow
Red/Flashing Yellow/Red

Name:
Diverging Approach Medium

Indication:
Proceed on diverging route not exceeding prescribed speed through turnout prepared to pass next signal not exceeding 35 MPH.
------------------------
Rule: 9.1.12

Aspects of Color Light & Semaphore Signals:
Red/Yellow
Red/Yellow/Red
Red/Red/Yellow
Red/Yellow/Dark

Name:
Diverging Approach

Indication:
Proceed on diverging route not exceeding prescribed speed through turnout; approach next signal preparing to stop, if exceeding 30 MPH immediately reduce to that speed.
------------------------
Rule: 9.1.13

Aspects of Color Light & Semaphore Signals:
Flashing Red
Red/Flashing Red
Red/Flashing Red/Red
Flashing Red/Red
Flashing Red/Red/Red
Red/Red/Flashing Red
Red (G) with Number Plate
Red/Red (G) with Number Plate
Red/Dark (G) with Number Plate
Dark/Red (G) with Number Plate

Lunar
Lunar/Red
Lunar/Red/Red
Red/Lunar
Red/Red/Lunar
Red/Lunar/Red
Dark/Lunar
Flashing Red/Dark
Dark/Flashing Red

Name:
Restricting

Indication:
Proceed at restricted speed.
------------------------
Rule: 9.1.14

Aspects of Color Light & Semaphore Signals:
Red with number plate
Red/Red with number plate
Red/Dark with number plate
Dark/Red with number plate

Name:
Stop and Proceed

Indication:
Stop, then proceed at restricted speed.
------------------------
Rule: 9.1.15

Aspects of Color Light & Semaphore Signals:
Red
Red/Red
Red/Red/Red
Red/Dark
Dark/Red

Name:
Stop

Indication:
Stop
==============

A visit to Al Krug's excellent site for some visuals may be in order:

http://www.vcn.com/~alkrug/rrfacts/signals/signals.htm

ddkid Wrote:
-------------------------------------------------------
> I was driving up New Avenue from Lockport to
> Lemont, Illinois, which parallels the old GM&O
> line from Chicago to St. Louis, the other night
> and trying to explain the meaning of the block
> signals to my wife, and found that I didn't
> remember as much from my train-riding days as I
> thought I did. Green means it's OK to enter the
> block at maximum speed, red means don't enter the
> block, there's a train in it, and yellow means
> that this block is clear but there's a train in
> the next block, or so I remember. What does a
> flashing yellow mean? Also, this line has high
> and low signals; I recall that they refer to the
> current block and the next one, but which is
> which? I remember crews calling the upper one lit
> yellow as "high yellow;" what does that signal
> mean? Do they have different meanings on
> different railroads? (I can already guess the
> answer to that one.) Is there a good Web site
> that has a rundown on this?

From the CN/IC section of the CORA guide, dated 7/15/2001 (funny, I use this CORA book more here than I do at work):

Advance Approach: Proceed preparing to stop at second signal , until it can be plainly seen that indication of second signal allows train to proceed.


Now if is this is the Former GM&O, that is now part of the UP (SPCSL) {I say this because I can't find New Ave. on any of the CN/IC maps in the CORA book} then the
UP Indication for Advance Approach is:
Rule 9.2.3 :Advance Approach: Proceed Prepared to Stop at Second Signal. Freight trains Exceeding 40 MPH must Immediately reduce to 40 MPH. Passenger trains may proceed but must not exceed 40 MPH passing next signal.

When next signal is seen to display an aspect more favorable than Diverging Approach or Approach, the requirement to proceed prepared to stop at second signal no longer applies. When Next signal is seen to display Clear, the 40 MPH speed requirement no longer applies.

Clear as Mud??

Yes, clear as mud. I guess the advice to look at the book for one's favorite railroad is the best.

Thanks to all that replied. Sorry not to have thanked you sooner but it's been a busy weekend.