[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR236.23]

[Page 642]
 
                        TITLE 49--TRANSPORTATION
 
       CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF 
                             TRANSPORTATION
 
PART 236_RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, 
 
              Subpart A_Rules and Instructions: All Systems
 
Sec.  236.23  Aspects and indications.

    (a) Aspects shall be shown by the position of semaphore blades, 
color of lights, position of lights, flashing of lights, or any 
combination thereof. They may be qualified by marker plate, number 
plate, letter plate, marker light, shape and color of semaphore blades 
or any combination thereof, subject to the following conditions:
    (1) Night aspects of roadway signals, except qualifying 
appurtenances, shall be shown by lights; day aspects by lights or 
semaphore arms. A single white light shall not be used.
    (2) Reflector lenses or buttons or other devices which depend for 
visibility upon reflected light from an external source shall not be 
used hereafter in night aspects, except qualifying appurtenances.
    (b) The aspects of cab signals shall be shown by lights or by 
illuminated letters or numbers.
    (c) Each aspect displayed by a signal shall be identified by a name 
and shall indicate action to be taken. Only one name and indication 
shall apply to those aspects indicating the same action to be taken; the 
same aspect shall not be used with any other name and indication.
    (d) The fundamental indications of signal aspects shall conform to 
the following:
    (1) A red light, a series of horizontal lights or a semaphore blade 
in a horizontal position shall be used to indicate stop.
    (2) A yellow light, a lunar light, or a series of lights or a 
semaphore blade in the upper or lower quadrant at an angle of 
approximately 45 degrees to the vertical, shall be used to indicate that 
speed is to be restricted and stop may be required.
    (3) A green light, a series of vertical lights, or a semaphore blade 
in a vertical position in the upper quadrant or 60[deg] or 90[deg] in 
the lower quadrant shall be used to indicate proceed at authorized 
speed.
    (e) The names, indications, and aspects of roadway and cab signals 
shall be defined in the carrier's Operating Rule Book or Special 
Instructions. Modifications shall be filed with the FRA within thirty 
days after such modifications become effective.
    (f) The absence of a qualifying appurtenance, the failure of a lamp 
in a light signal, or a false restrictive position of an arm of a 
semaphore signal shall not cause the display of a less restrictive 
aspect than intended.

[33 FR 19684, Dec. 25, 1968, as amended at 49 FR 3383, Jan. 26, 1984]