Change List for this Rule


General Order 95


Section VII


Detailed Construction Requirements for Trolley and Electric Railway
Contact and Feeder Conductors and Their Supporting Messengers,
Span Wires, Etc. (Class T Circuits)

77.4    Clearances


The basic clearances for trolley span wires are specified in Table 1, Column C and inTable 2, Column A.  Modifications of these basic clearances are specified in Rules 37 and 38 and by the following provisions:


A.    Above Railways

vertical clearance of 22.5 feet above rails for trolley span wires (Table 1, Case 2, Column C) may be decreased to 19 feet where the railway involved does not transport nor proposes to transport freight cars.


Note:    Revised February 1, 1948 by Supplement No. 1 (Decision No. 41134, Case No. 4324).


B.    Under Bridges, ETC


A reduction of the clearance given in Table 1 to a clearance of not less than 14 feet above rails is permitted for trolley span wires under bridges, in tunnels, or in subways, provided the railways does not transport freight cars where the vertical distance from the top of car or load to trolley contact conductor is less than 6 feet.  The grading of the level of trolley span wires from the basic clearance to this reduced clearance is permitted at approaches to bridges, tunnels, or subways.


Note:    Revised January 21, 1992 by Resolution SU–10.


C.    From Conductors


The clearances of trolley span wires from conductors shall be as specified in Table 2, Column A, except as modified by the provisions of Rules 74.4-G and 78.


D.    From Guys or Span Wires


The clearance specified in Table 2, Case, Column A (18 inches) is not required between trolley span wires, backbones, messengers, and similar wires or cables, used to support trolley contact conductors and appurtenances.


E.    From Poles and Crossarms


The clearances specified in Table 1, Column C, Cases 8 and 9, are not intended to apply insulated (unenergized) portions of span wires, backbones, messengers, pulloffs and similar equipment at the poles to which they are attached.


Note:    Revised January 13, 2006 by Decision No. 05-01-030