Pittsburgh & Lake Erie Railroad
Historical Society

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Pittsburgh & Lake Erie Railroad,
its predecessors, subsidiaries and affiliates.


Three Color Signal Aspects


The information on this page was compiled from
the instruction manual printed by the Pittsburgh and Lake Erie Railroad,
LEARNING THE NAMES OF SIGNAL INDICATIONS,
dated July 1, 1979.
 

 

The name of the signal displaying three RED lights is STOP SIGNAL.

The name of the signal is read from the top position down. When Red is used with Green or Yellow, Red is not considered because it contributes nothing to the name of the signal. It remains lighted to let you know it is in working order and to show the relationship of the other lights - whether in top, middle, or bottom positions.

Putting it another way - "If it's not all Red, it's not Red at all."


 

The addition of a number plate displayed with a STOP SIGNAL indication changes the name to STOP AND PROCEED. The train must STOP AND then may PROCEED at Restricted Speed.

Restricted Speed definition - Proceed prepared to stop short of train, obstruction or switch not properly lined; looking out for broken rail and not exceeding 15 miles per hour.

Signals with NUMBER PLATES are not controlled by the Train Dispatcher of Operator. They automatically respond to track occupancy. Signals without NUMBER PLATES are called HOME SIGNALS and, but for a few exceptions, are all controlled by the Train Dispatcher or Operator. The few exceptions are covered in Timetable Special Instructions. A controlled HOME SIGNAL will normally display STOP except when lined for an immediate movement.


 

The name of the signal with a Green over a double Red is CLEAR. This means the train may proceed at Normal Speed which is the maximum authorized speed.


 

When a color (Green or Yellow) is displayed in the middle position, it also indicates MEDIUM Speed. When the Green moves from the top position to the middle position, the name is MEDIUM CLEAR - MEDIUM because the Green is in the middle position and CLEAR because the color is Green. MEDIUM CLEAR means to Proceed: Medium speed within interlocking limits. When the entire train clears the interlocking limits Normal Speed may be resumed.

Medium Speed Definition - Not exceeding 30 miles per hour.


 

Flashing a signal increases the speed instruction conveyed. This is considered a fail-safe system because if the flashing unit fails the steady light will indicate a lower and safer speed. When the Green is flashing in the middle position the name is LIMITED CLEAR - LIMITED because the Green is in the middle position AND flashing and CLEAR because the color is Green. LIMITED CLEAR means to Proceed: Limited Speed within interlocking limits. When the entire train clears the interlocking limits Normal Speed may be resumed.

Limited Speed Definition - Not exceeding 45 miles per hour


 

When the Green is in the bottom position, the name is SLOW CLEAR - SLOW because the Green is in the bottom position and CLEAR because the color is Green.SLOW CLEAR means to Proceed: Slow speed within the interlocking limits. When the entire train clears the interlocking limits Normal Speed may be resumed.

Slow Speed Definition - Not exceeding 15 miles per hour.


 

When the Yellow color is in the top position it means APPROACH. APPROACH means to approach the next signal prepared to stop and a train exceeding Medium Speed must at once reduce to that speed.


 
MEDIUM APPROACH means to proceed at Medium Speed preparing to stop at the next signal.

 
LIMITED APPROACH means to proceed at Limited Speed preparing to stop at the next signal.

 

When the Yellow drops to the bottom position, it loses its identity as Approach and becomes the most restriced speed. The name is RESTRICTING.

RESTRICTING means to proceed prepared to stop short of train, obstruction or switch not properly lined; looking out for broken rail and not exceeding 15 miles per hour.

A steady Yellow on the bottom is ALWAYS Restricting.


 

To show SLOW APPROACH we must flash the yellow on the bottom to upgrade the speed form Restricted to Slow. A flashing yellow on the bottom is SLOW APPROACH. SLOW because the Yellow is in the bottom position AND flashing and APPROACH because the color is Yellow.

SLOW APPROACH means to proceed preparing to stop at next signal; Slow speed within interlocking limits.

 
 

Up to this point, the signals have only used a single color to display instructions to the train crew.  The following signals combine two colors to display instructions.  Remember these rules when reading signals with two colors displayed:

The name of the signal is read from the top position down.

A color, Green or Yellow, in the top position gives the basic indication, CLEAR or APPROACH.

A color, Green or Yellow, in the middle position indicates Medium Speed.

A flashing Green or Yellow in the middle position indicates Limited Speed.

A steady Green or flashing Yellow in the bottom position indicates Slow Speed.

A steady Yellow in the bottom position always indicates Restricted Speed.

A Red contributes nothing to the name of the signal unless the signal is all Red.  If it's not ALL RED, It's not RED at all.

 


 

When a signal has a Yellow in the top position and a Green in the middle position, it's name is APPROACH MEDIUM.

APPROACH because the color is Yellow and in the top position.

MEDIUM because the second color, Green, is in the middle position.

The Red contributes nothing to the name.

APPROACH MEDIUM means to proceed approaching the next signal at Medium Speed..


 

When a signal has a Yellow in the top position and a Green in the middle position and flashing, it's name is APPROACH LIMITED.

APPROACH because the color is Yellow and in the top position.

LIMITED because the second color, Green, is in the middle position and flashing thus upgrading the speed from Medium to Limited.

Again, The Red contributes nothing to the name.

APPROACH LIMITED means to proceed approaching the next signal at Limited Speed.


 

When a signal has a Yellow in the top position and a Green in the bottom position, it's name is APPROACH SLOW.

APPROACH because the color is Yellow and in the top position.

Again, The Red contributes nothing to the name.

SLOW because the second color, Green, is in the bottom position.

APPROACH SLOW means to proceed approaching the next signal at Slow Speed and a train exceeding Medium Speed must at once reduce to that speed.


 

This signal's name is MEDIUM APPROACH SLOW.

The Yellow in the middle tells you that the speed comes first in the name.

The middle position of the first color considered tells you the speed is MEDIUM.

The Yellow color in the middle position tells you it is an APPROACH.

The Green on the bottom indicates SLOW speed.

MEDIUM APPROACH SLOW means to proceed at Medium Speed approaching the next signal at Slow Speed.


 

This signal's name is MEDIUM APPROACH MEDIUM.

The Yellow in the middle tells you that the speed comes first in the name.

The middle position of the first color considered tells you the speed is MEDIUM.

The Yellow color in the middle position tells you it is an APPROACH.

The Green on the bottom is flashing so the SLOW speed is upgraded to MEDIUM speed.

MEDIUM APPROACH MEDIUM means to proceed at Medium Speed approaching the next signal at Medium Speed.