1999 Avenue of the Stars is a 39 story office tower located on the western edge of Century City midway between Beverly Hills and Westwood. The original window washing system was over 20 years old and in need of replacement.
Sky Rider Equipment Co., Inc. was selected as the window washing equipment contractor to remove and replace the original machine. A track mounted Building Maintenance Unit (BMU) with a luffing boom and two Platform lengths was provided.
As with most projects, this one has numerous challenges. They were as follows:
The existing system originally utilized a concrete runway system. The owners elected to have a track system installed. Because the building was over 500 feet tall, a ground based truck crane would not reach and a helicopter was too expensive due to the large number of lifts. Half of the roof had a 22 foot high parapet which had to be cleared to allow the platform to swing outboard. The building was occupied, so very little equipment could pass through the interior. The building’s front entrance couldn’t accommodate the weight of a semi-truck, so lifting to the roof required an intermediate step of transferring to the top of the parking structure.
To begin, 112 pedestal positions had to be located above existing structural steel. At each of those locations, the concrete runway and the concrete deck below that had to be opened to expose the structural steel. After each pedestal was welded to the structural steel, new concrete was poured and finished level to the existing roof height.
As the pedestal installation was being completed, a 5000# capacity roof crane was installed to do the lifting. The crane was first mounted on the upper level of the parking structure to bring the track and the BMU from the unloading area below to the top of the parking structure. After all of the equipment was staged on the parking structure, the crane was reinstalled on the building roof to bring it all up to that level for installation. The crane is also utilized to assemble the roof car.
The BMU was designed with numerous features specifically to accommodate the challenges of the building design. The machine has a spreader bar at the end of the luffing boom which extends and retracts to accommodate the suspension points of two different platform lengths. The boom, which extends 26 feet, luffs to a height above the roof of 35 feet, more than sufficient to clear the high parapet. In addition, the spreader bar rotates 270 degrees and, of course, the entire assembly moves laterally along the track to access the 30 work positions around the building.
For smooth, quiet and reliable operation, all of the platform hoisting equipment is located on the roof carriage. The four wire ropes supporting the platform contain control conductors eliminating the need for a bulky power cord typically utilized on a self powered platform (such as the one being replaced). Because the wire ropes are wound on a roof car mounted drum, they are subject to very little wear, providing an extended service life.