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Elevator World Project of the Year: Collins House

Otis works within space and time constraints to deliver advanced elevators to new landmark tower.

Elevator World Project of the Year: Collins House

This article was originally published in the January 2021 edition of Elevator World magazine

For more than 150 years, owners and managers of some of the world's most iconic and unique buildings have called on Otis to deliver the solutions and service their buildings need. From the Empire State Building to the Eiffel Tower, Otis moves passengers throughout some of the world's most famous landmarks. So, it should come as no surprise that the company was selected to provide its elevator products for the 61-story Collins House residential tower in Melbourne, Australia. Otis contributed two SkyRise® elevators and one Gen2® Premier elevator to the project, as well as the company's CompassPlus® destination management system, products worthy of a landmark skyscraper noted for its unique design. Otis also successfully met unique installation challenges, not the least of which was delivering equipment to the site across a busy tram route that travels down Collins Street.

A strong history of customer service and innovation, coupled with experience in meeting challenging building design and installation requirements, allowed Otis to provide an ideal elevator solution for this distinctive, prestigious project.

Collins House's exterior dimensions measure 11.5 m (37.7 ft) wide at its base, making it Australia's slimmest tower and the fourth-slimmest skyscraper in the world. Architecture firm Bates Smart designed this "skinnyscraper" to match the Collins House footprint, which isn't much bigger than Melbourne's typical house and land block. The building features a slenderness ratio of 16.25:1, coming in significantly less than the ratio of approximately 24:1 for New York's Steinway Tower, the world's slenderest skyscraper.

The sleek, contemporary tower incorporates the grand heritage façade of Melbourne's historic Makers Mark building on downtown Melbourne's Collins Street. NYC has its Wall Street, Paris is known for the Champs-Élysées, and Singapore boasts Orchard Road; in the same way, Melbourne has Collins Street, one of the most prestigious streets in Australia. With nearly 260 luxurious residences — a mix of multistory lofts, expansive single-level apartments and an exclusive penthouse collection — Collins House is a draw for its design, as well as its high-end amenities. The residences were designed with views in mind but are notable, as well, for their oak floorboards, marble splashbacks, glass cabinetry and brass fixtures.

Because of the building's small footprint, Collins House extends up from behind the Makers Mark façade and then cantilevers 4.5 m out on one side over an existing 11-story office building next door. (Collins House's developer purchased the air rights above the building to allow the development to proceed as designed.)

Elevator World Project of the Year: Collins House
Left: An elevator car interior with leather wall panels
Right: A unit inside Collins House; image courtesy of Hickory

Construction contractor Hickory Group used its construction method, Hickory Building Systems (HBS), to develop prefabricated structural modules designed to improve quality and safety and streamline the overall construction process. Collins House is the tallest residential tower in Australia to utilize modular components, and the HBS prefabricated construction method resulted in minimum disruption to traffic and a substantial reduction in the duration of the construction timeline — from 40 to 30 months. The self-supporting structure utilizes conventional formwork up to Level 14, at which stage the prefabricated units were used for the remainder of the project. A cantilever floorplate at Level 15 enables floor space to increase by approximately 35% to the very top.

While the small footprint was a challenge for the builder and the Otis design team, a single point of access at the front of the Makers Mark façade created issues with the amount of room available to maneuver various pieces of construction equipment and building material required. The logistics of delivering, setting up and moving materials and equipment during construction on the site required clear communication and well-organized, just-in-time delivery.

A strong history of customer service and innovation, coupled with experience in meeting challenging building design and installation requirements, allowed Otis to provide an ideal elevator solution for this distinctive, prestigious project.

Transportation System Details
The particularly narrow Collins House site required a rethinking of the structure of tall buildings. It was only through an inventive structural system (combined with cutting-edge construction techniques and advanced systems that met the building requirements in the time required) that a reinvention of the tall skyscraper concept was achieved.

Otis supplied a Gen2 elevator for Collins House that travels from the basement level to Level 19 and SkyRise elevators that travel from the ground floor to the upper floors. The three elevators utilize the same triplex elevator shaft, with the two SkyRise units changing to a duplex shaft after Level 20. "In addition, once we completed the Gen2 installation, Hickory used it to fit out the lower part of the building, while we continued the installation of the two SkyRise units above," said Jeremy Miles, Otis' technical support team leader for new equipment & modernization.

Elevator World Project of the Year: Collins House
The elevator system uses a triplex arrangement for the two SkyRise elevators and the Gen2 Premier shaft, seen on the right side.

"Otis was chosen to provide the elevators for Collins House based on their industry high-rise experience and value," said Hickory Project Manager Peter Frank. SkyRise, Otis' most advanced high-rise system, integrates technology with space­saving design that gives building designers flexibility in realizing their visions.

SkyRise was perfectly suited for the "skinny" design of the Collins House project. The sustainable design of SkyRise minimizes space requirements, and the elevator's SkyMotion® machines are among the most energy-efficient available. Their lighter weight makes them easier to install, and their smaller footprint saves space. The elevator's controller is built with fly-by-wire technology, similar to that used in aircraft, to provide reliability in a compact design. The controller helps reduce energy consumption, while a patented control algorithm ensures a smooth ride.

The Gen2 system is one of the company's best-selling elevators, with more than 1 million sold since its launch in 2000 (ELEVATOR WORLD, December 2020). Gen2 features flat-belt technology that allows for a compact design, energy-efficient operation and a smooth, quiet ride. The compact system gives architects greater design flexibility and building owners more rentable space. The flat-belt technology, ReGen® drives and gearless machines make the Gen2 Premier among the world's most energy-efficient elevators. The system minimizes noise and vibration and renders the elevator's movement barely perceptible. The belts have a significantly smaller bending radius than wire rope, allowing the Gen2 machine to be 50% smaller than conventional machines. When combined with the ReGen drive system, the system can reduce energy consumption by 75% under normal operation. ReGen captures energy that would otherwise be wasted and returns it to the building's power grid for use by other systems. Significantly, the machine-room-less elevator components are so compact, they fit inside the hoistway, eliminating the need for an extra room for elevator components. This was a perfect fit for Collins House, as the system saved construction costs and freed valuable floor space.

The CompassPlus fixtures are easy to use and offer efficient movement throughout the building up to 50% faster than conventional destination-management systems. The intuitive screens guide passengers through their journey with customized service.

A challenge for Collins House construction teams was the delivery of material when and where it was needed. A decision was made to retain the original Art Nouveau detailing from the 1908 Makers Mark building, incorporating it into the façade and grand entrance hall of Collins House as a way to pay respect to the site's heritage as the center of Australia's national trade network in the early 1900s. But, because the site's footprint was so small, it meant early delivery of materials had to come in through the Collins Street entrance. This also meant there was limited space onsite for storage of equipment.

"Effective communication was absolutely critical to delivery of materials," Frank said. "Time slots were allocated to various trades, with due respect to peak traffic periods, and the delivery times were rigidly followed to avoid conflicts."

Because Collins Street is a major Melbourne thoroughfare, Otis required a permit from the city to schedule its early deliveries through the front entrance on consecutive Saturdays, on an extremely tight schedule. Complicating matters was Melbourne's tram transportation system. Trams are a major form of public transportation in the city, consisting of a network of some 250 km of double track serving 493 trams, 24 routes and 1,763 stops. Tram service on Collins Street meant Otis had only a 5-min window between trams to deliver equipment.

Elevator World Project of the Year: Collins House
The Collins House lower ground elevator lobby

Once the building's early floors were completed, Otis' remaining material (including shaft rails, motors and elevator cabs) had to be staged progressively throughout the build via a single crane and a single hoist lift, both of which required reserving a specific time to use.

Miles said: "Multiple deliveries of small loads each time made the process extremely time-consuming. Our team mapped out a thorough plan before work started and throughout the project to ensure a timely delivery of our elevator products; one that didn't impede progress by the builder or trade professionals, like electricians or plumbers. We worked closely with Hickory, our customer, to coordinate our schedules and ensure the project flowed smoothly."

The floors of Collins House have an H-shaped plan, which eliminates the need for perimeter columns. As a result, each precast floor, precast post-tensioned beams and pre-installed façade (constructed and assembled offsite) was craned into place in 2-3 hr. That meant the elevator shaft rail installation had to keep pace with a four-day structure cycle time as the building grew taller. "The use of a precast elevator shaft and prefabricated floors made progress swift, and we had to keep pace to not fall behind," Miles said.

An example of the speed of the installation was the SkyRise builders' elevators, which were completed less than 30 days after the motor room was completed. That was of particular importance, because wiring for the Compass system between the three elevators needed to be integrated, which was difficult because the Gen2 and SkyRise elevators were nearly 40 floors apart. "It was a challenge to link Compass and other group communications between the units, particularly while construction was ongoing, but the systems [operated] seamlessly," Miles said.

Elevator World Project of the Year: Collins House
A unit inside Collins House; image courtesy of Hickory

To ensure SkyRise system performance, Otis conducted advanced simulation and analysis to understand site-specific variables, such as building sway and stack effect. Miles noted: "One of the things we had to deal with as it relates to [building] sway was when the crane was in use. When it was loading material and lifting to upper floors, the building would sway. We saw a lot of movement from that, as well as from the effects of wind. As a result, we wound up doing a lot of rail installation during the night, when the crane wasn't in use, to ensure the rails were installed as straight as possible."

Rail straightness also was affected by the building's unique design. Because Collins House was cantilevered, the structure was progressively stepped back throughout the build to ensure it would not lean more than an expected 300-400 mm. As a result, at project completion, the structure was only about 30-40 mm out. "However, the cantilevering and stepping back of the shaft, as well as crane movement during construction, made the shaft challenging to plumb," Miles said. "Despite this, our team did a great job ensuring excellent ride quality for the customer."

Frank added:
"To counteract unequal settlement, the structure was built with offsets at every level, and the building verticality was regularly monitored. The lift rails were installed in symmetry with the building movement so that the finished building and elevators remained vertical. Logistics also were critical, in that there was no space for storage of materials." Summarizing, Miles said: "The Collins House project is an excellent example of Otis' ability to provide the right products for a customer's unique needs, as well as successfully work within a demanding construction environment under tight deadlines."

The project was completed in November 2019.

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