Why supertall towers have super-fast elevators

Dive Brief:

The world's tallest towers tend to have the fastest elevators, according to a new report from the Chicago-based Council on Tall Buildings and Urban Habitat.
The elevator at China's Shanghai Tower reaches a speed of 67 feet per second during its 1,898-foot-long continuous vertical run. It's followed closely by the system at the CTF Finance Center in Guangzhou, China, which travels 1,695 feet at up to 66 feet per second.
The fastest elevators and the tallest continuous vertical runs are located almost entirely in Asia and the Middle East, with New York City's One World Trade Center the only North American building to make the list. The 1,776-foot-tall tower's elevator travels at up to 33 feet per second.

Dive Insight:

Building designers are in a race to the top, and the vertical transportation industry is right there with them. That's led to innovations like carbon-fiber cables and magnetic levitation systems, which replace hefty steel ropes, as well as destination dispatch technology to control access and move people through the building smoothly.

Even if the height of a supertall, which the CTBUH classifies as topping 984 feet, seems unnecessary, the restrictions it places on building systems have driven improvements in efficiency. After all, if a building is going to have a 163rd floor, occupants and visitors must be able to reach it — and you can't count on them taking the stairs.

Consider the steel ropes used to raise and lower typical elevator cabs. Aaron Ites, senior vice president of the new equipment business at Kone Americas, told Construction Dive in July that the biggest challenge in designing elevator systems for supertalls is the weight and mass those ropes entail. Transfer floors are used to manage the resulting size of the elevator installation, which can be significant in a tall building.

Towers banking on a slender footprint or wanting to make a statement are now turning to other options. One of them is a carbon-fiber cable created by Kone in 2013. UltraRope is lighter and thinner than steel, allowing for longer runs. It will be used in the Jeddah Tower, underway in Saudi Arabia. Expected to wrap up next year, the tower will reach more than 3,280 feet (1 kilometer).

German elevator-maker Thyssenkrupp is looking sideways, in addition to up and down, with its new Multi technology. The cable-free system uses magnetic levitation to move elevator cars vertically and horizontally at speeds of up to 22 miles per hour.

Thyssenkrupp also installed the elevator at One World Trade Center, in New York City. Although it didn't use the maglev system there, it had efficiency in mind for that project, too. Power is generated when the elevator brakes, producing up to 300kW of energy.