4 Colo. Code Regs. § 723-7-7325 : Department of Regulatory Agencies — Public Utilities Commission —7 - RULES REGULATING RAILROADS, RAIL FIXED GUIDEWAYS, TRANSPORTATION BY RAIL, AND RAIL CROSSINGS —SAFETY —Railroad Clearances —7-7325 - Side Clearances

(a) Generally.
(I) Side clearance generally shall be at least 8'6".
(II) Wherever practicable, all posts, pipes, warning signs, and other small obstructions should be given a side clearance of at least 10'0".
(III) Side clearance may be reduced to comply with provisions of subparagraph (c)(I).
(b) Platforms.
(I) The side clearances in this paragraph to apply to both main line and side tracks unless otherwise indicated.
(II) The minimum side clearance for platforms that are 8" or less above top of rail shall be 5'0".
(III) For platforms that are greater than 8" above top of rail and 4'0" or less above top of rail:
(A) The minimum side clearance for freight platforms on side tracks shall be 6'3" or 8'0".
(B) If side clearance is reduced to 6'3" on one side, a full clearance of 8'0" shall be maintained on the opposite side.
(C) No intermediated clearance is permitted, except compensation for curvature under paragraph (i).
(D) The minimum side clearance for freight platforms on main line tracks or passing tracks shall be 8'6".
(IV) For platforms that are greater than 4'0" above top of rail:
(A) The minimum side clearance on side tracks shall be 8'0".
(B) The minimum side clearance on main line and passing tracks shall be 8'6".
(V) Combination platforms. Platforms covered under subparagraph (b)(II) may be combined with platforms covered under either subparagraph (b)(III) or (b)(IV) provided that the lower platform presents a level surface to the face of the wall of the platform with which it is combined. No other combinations are permitted.
(VI) The minimum side clearance for all other platforms shall be 8'0".
(A) This subparagraph (VI) applies to side tracks only.
(B) Retractable platforms, either sliding or hinged, which are attached to a permanent structure, must be so constructed that, when retracted or in a non-working position and firmly secured or anchored, the resulting clearance shall not be less than clearances mandated by rules 7321 through 7328.
(c) The minimum side clearance for bridges and tunnels shall be 8'0".
(I) Lower section of bridges and structures of bridges.
(A) This subparagraph applies to those sections of bridges and structures of bridges that are at or below 4'0" above top of rail.
(B) Hand rails, water barrels and refuge platforms on bridges and trestles, water columns, oil columns, block signals, or cattle guards, or portions thereof, which are 4'0" or less above top of rail, may have clearances decreased to the extent defined by a line extending diagonally upward from a point level with the top of rail and 5'6" distant laterally from center line of track to a point 4'0" above top of rail and 8'0" distant laterally from center line of track.
(C) The clearances authorized in this subparagraph (I) are not permitted on through bridges where the work of train-men or yardmen require them to be upon the decks of such bridges for the purpose of coupling or uncoupling cars in the performance of switching service on a switching lead.
(II) Upper section of bridges and tunnels.
(A) This subparagraph applies to those sections of bridges, structures of bridges, and tunnels that are greater than 16'0" (Diagram I) or 15'9" (Diagram II) above top of rail.
(B) Side clearances in tunnels and through bridges may be decreased to the extent permitted by paragraphs 7324(c) and (d).
(d) The minimum side clearance for all of the following shall be 3'0":
(I) switch boxes that project 4" or less above top of rail;
(II) switch operating mechanisms that are necessary for the control and operation of signals and that project 4" or less above top of rail; and
(III) interlockers that project 4" or less above top of rail.
(e) The minimum side clearance for mail cranes and train order stands shall be 8'6", but only when such cranes or stands are not in an operative position.
(f) The minimum side clearance for oil and water columns shall be 8'0", except as provided by subparagraph 7325(c)(I)(B).
(g) Signals or switch stands.
(I) The minimum side clearance for signals and switch stands shall be 6'0", if such signals or switch stands are 3'0" high or less above top of rail when located either between tracks or where it is not practicable to provide clearances as otherwise prescribed in rules 7321 through 7328.
(II) The minimum side clearance for signals or switch stands that are over 3'0" high shall be 8'3".
(III) Signals and signal poles higher than 3'0" above top of rail shall, for the portions thereof that are higher than 4'0" above top of rail and less than 16'0" above top of rail, keep such portions 8'6" from center of track. The portions thereof that are below 4'0" and over 16'0" shall not encroach on the limits illustrated by Diagram II.
(h) Buildings and entrances.
(I) The minimum side clearance inside buildings shall be 8'0".
(II) At elevations of 4'0" or less above top of rail inside of buildings, the minimum side clearance may be reduced on one side of the track to 6'3", provided that 8'0" is maintained on the opposite side.
(III) The minimum side clearance at building doors shall be 7'0".
(IV) Side clearance at doors may be reduced to 5'9" on one side of track only, provided a full clearance of 8'3" is maintained on the opposite side.
(i) Curved track. The horizontal clearances specified in rules 7320 through 7328 relate to tracks on tangent. On curved track the clearances shall be increased to allow for the over-hang and the tilting of a car 85 feet long, 60 feet between centers of trucks, and 14 feet high.
(j) The minimum side clearance for material, merchandise, or other articles adjacent to tracks shall be 8'6".
(k) Engine houses, shop buildings, and passenger platforms, at car floor height, are exempt from this rule.

4 CCR 723-7-7325