California Academy of Sciences
Location: San Francisco, CA
Completion Date: 2008
Basic Equipment List: Monorail Track, Trolley, Wire Rope System
California Academy of Sciences is located in Golden Gate Park, San Francisco, California. Sky Rider was selected to install window washing equipment in the interior of the Rain Forest dome and on the Living Roof.
Rain Forest Dome
The Rain Forest dome consists of a 90 foot diameter glass dome supported by a tubular steel frame. The challenge was to provide access to the underside of the glass for cleaning as well as for access to lighting and other mechanical elements of the dome including its structure. Sky Rider met this challenge by creating an arched aluminum track that mimics the curvature of the dome structure. The upper end of the arched track is supported by a pivot at the interior apex of the dome. The lower end is supported by another trolley that engages a circular monorail supported by the dome framework at the approximate mid-point of the dome. This allows 360 degree rotation and access to the entire upper part of the dome.
Wire ropes are permanently installed on the arched track with one end attached near the pivot. The wire ropes are of sufficient length to travel the distance of the track, onto the trolley, then to the floor below. The wire ropes are fed through a hoist on an integrated work cage to lift personnel from floor level to the trolley on the arched track. The work cage is then coupled with the trolley to allow travel to the top of the arched track. When the work cage is lowered back to the floor, the work cage may be disconnected from the wire ropes for storage outside the dome when not in use. Power for the work cage is supplied through a slip-ring at the pivot point to allow for continuous rotation of the arched track.
The living roof at the Academy is 197,000 square feet of vegetation that requires constant attention and monitoring. Because of numerous locations where there is potential for a fall, Sky Rider installed a system of interconnecting wire ropes for workers to attach to. These wire ropes are located on the hilly areas above the two domes (including the rain forest dome) and adjacent to skylights.
Prior to delivery of the Arched Track, Trolley and Pivot assemblies to the site, a full scale mock-up of the system was suspended from temporary supports. The trolley was tested through its full range with a hoist and counterweight simulating the weight of the work cage plus rated (live) load plus an additional 25%.
The pivot assembly was attached to the structure using heavy steel U-bolts. The pivot housing allows 360 degree rotation on a slewing ring bearing. The housing contains a slip ring to provide power to the work cage regardless of the direction or number of rotations the beam goes through.
The curved monorail track was fabricated by Sky Rider from sections of 4X6″ steel tube with a 1″ opening laser cut along its length and bent so that when assembled, it completed a full circle. An aluminum trolley was built to mate the arched track to the monorail track for easy and continuous movement.