There are more than 450 built high-rise buildings in Frankfurt am Main according to SKYDB. The construction of high-rise buildings is not a special discipline in Germany, as the legally defined high-rise limit is only 22 meters. While lower skyscrapers make do with standard elevator models, skyscrapers use special high-performance elevators. Such optimized elevators for high-rise applications have coordinated systems for drive, control and regulation. High-rise elevators can reach speeds of up to 10 meters per second and payloads of up to 4 tons. But before elevator systems can be installed, they have to be carefully planned.

The planning of elevator systems starts with the simulation on the computer. To avoid waiting times within the building, it is essential to plan the expected traffic flows in advance. Otherwise, crowding in front of elevators, in the storage areas and in the circulation areas is inevitable. For this purpose, specialist planners for elevator systems and elevator manufacturers offer so-called traffic analyses or traffic calculations. In this process, the key data of the building to be erected, its use, the function types and the visitor flows are entered into a digital calculation system with the aim of achieving a simulation of later use.

By entering further parameters such as elevator type, number of installations and times for elevator door cycles, the software then determines conveyance capacities accordingly. Even special situations such as heavy visitor traffic or the failure of several elevator systems can be simulated on the computer and taken into account when designing the elevator system.

Outstanding key figures in the evaluation of traffic flow are transport capacity and arrival rate. The arrival rate indicates how many passengers arrive at an elevator (or elevator group) to be transported in a given period of time. In contrast, the transport capacity indicates the actual number of passengers transported. As long as the elevator (or elevator group) is able to transport all arriving passengers without waiting times, arrival rate and transport capacity are equal. The average waiting time for the elevator should be about 30 seconds in office buildings.

After the traffic analysis has been carried out, the structural design planning is due. For this purpose, data must be read from the plans for the construction site. In particular, the dimensions of shafts, cabs and machine rooms are relevant here. In addition, the Hessian high-rise building guideline provides specifications for the installation of the elevators. For example, it states that each floor must be served by at least two elevators. Elevator vestibules are also mandatory for each landing door, providing direct access to a stairwell. In addition, a firefighters’ elevator with special equipment is required to stop at any floor at any time.

In high-rise projects, groups of two to ten units are provided for the efficient operation of passenger elevators. These are located near the entrance area with direct access to the corridors. Elevator cars have a nearly square floor plan to ensure quick entry and exit.

n higher skyscrapers, elevators are grouped together to serve only certain floors. The idea behind this is simple: the fewer stops there are along the way, the faster passengers reach their destination. A short-distance group serves the lower floors in a high-rise tower, while a long-distance group serves the floors in the building head. Mid-range groups are also used for buildings with 40 stories or more. In high-rise buildings with different groups, it is also common for at least one stop to be served jointly by two groups for transfer.

The use of double-deck cabins can additionally increase transport capacity in heavily frequented buildings. In this case, two cabins are arranged one above the other, with two floors being served simultaneously. In this configuration, high-performance escalators are installed in the entrance floor (foyer), allowing passengers to access a gallery floor above and thus the upper elevator car.

Group control can make a decisive contribution to a smooth flow of visitors. After receiving a floor call, the elevator control system determines the elevator that can service the call most quickly.

In recent years, traffic management systems have been increasingly used in high-rise buildings. This involves making as few intermediate stops as possible during an elevator ride. To this end, passengers enter their destination days at a terminal on their way to the elevator. The system then groups the best possible control of all cabs from the various ride requests of all waiting passengers.

New elevator systems, such as those from Schindler Aufzüge in the OmniTurm, use a code card to take passengers to the right place in the high-rise tower. In addition, special features can be stored on the identification medium, which, for example, assigns an empty car to a wheelchair user or extends the door opening time.

In office towers, elevators can account for up to 15 percent of the building’s total energy consumption. Accordingly, building owners are increasingly attaching importance to resource-saving models that also have positive effects with regard to building certification according to systems such as DGNB or LEED.

Among the best-known elevator designers for high-rise buildings are Jappsen Ingenieure and ATEC Ingenieurgesellschaft. But the elevator manufacturers themselves also usually offer planning services.

Elevators from major elevator manufacturers such as Otis, Kone, Schindler and ThyssenKrupp are regularly installed in the high-rise city of Frankfurt am Main.