Section 7.486. Line structures

(a) Towers. The intermediate supports for return rope sheaves shall be of sufficient size to prevent failure under the most adverse design loading plus winds of 40 miles per hour from any direction. If guide wires or braces are used, they shall be clearly marked and be so located as to provide a minimum clearance as required in § 7.483 (relating to path of rope). There shall be no spikes, hooks or other projections on the hauling rope side, or on the downhill side, of the tower, lower than 7 feet above the surface of the tow path.

(b) Foundations. Foundations for intermediate towers shall be below the frost line or anchored to a ledge. If utility-type poles are used for intermediate towers, they shall be set into the ground a minimum of 4 feet with the backfill well tamped. If the soil has insufficient bearing capacity to prevent overturning with the most adverse design load condition plus winds of 40 miles per hour then guys or braces shall be used.

(c) Guards. Wherever moving parts are less than seven feet above the maximum snow depth, they shall be guarded in such a manner as to prevent accidental contact by the public or skiers using the tow. All persons shall be prevented from passing under the counterweight or contacting any attachments thereto by fences or guards.

(d) Sheaves and mounts. Return rope sheaves shall be mounted high enough on intermediate towers to hold the rope at least seven feet above maximum snow conditions. The sheave mountings shall be sufficiently strong to prevent failure under the most adverse design load conditions plus winds of 40 miles per hour. If the vertical component of the rope tension is not sufficient to hold the rope in the sheave groove at all times, then a proved device shall be used to prevent the jumping of the rope off the sheave. This applies to sheaves supporting the rope as well as those holding it down.