§ 7.425. Towers.
(a) Towers shall be located to conform to the profile of the terrain and designed to provide clearance of the cabins and ropes from all obstructions and ski or hiking trails. Under the most adverse loading conditions, a minimum space of 5 feet shall exist between the lower edge of the cabin or ropes and the terrain or other possible obstacles, including snow pack. Whenever the space is less than 15 feet, a protective fence shall be erected to divert all surface transportation or persons from possible collision.
(b) On monocable tramways, the tower arrangement shall be such that the hauling rope may not depart from a group of tower rollers should the tension in the hauling rope become twice its most unfavorable design value at that point. If a factor of less than two is used, adequate retaining rollers, properly placed, shall be provided. Where the rope load is normally upward, that is, where ‘‘hold-down’’ or ‘‘depression’’ rollers are used for normal operating conditions, the rope shall not leave the group of rollers under a condition in which twice the normal concentrated design load passes the tower while the rope is under normal design tension.
(c) On bicable tramways, the tower arrangement shall be such that the track cable under the most adverse operating conditions has a positive break over angle at the saddle. If angles of less than one degree are unavoidable, provision shall be made to keep the track cable in the saddle. Such provisions shall not interfere with any track cable in the saddle nor with any track cable brake operation.
(d) Towers shall be so located as to minimize the surge of the line under operating conditions. Local wind conditions shall be taken into consideration. Towers and ropes shall be so arranged as to prevent the collision of passing cabins in the event of lateral swinging due to winds.
(e) At passing places, the distances between the two cabins swung ten degrees inward from the vertical should be at least 2 feet, 6 inches. In no case shall this distance be less than 0.5% of the span length.
(f) Towers containing provision for change in height of rope and cable supports shall not be used.
Cross References This section cited in 34 Pa. Code § 7.421 (relating to definitions); 34 Pa. Code § 7.422 (relating to applicability); 34 Pa. Code § 7.428 (relating to line structures); and 34 Pa. Code § 7.431 (relating to signs).
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