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A9 Paper #8095

Disclaimer—This paper partially fulfills a writing requirement for first year (freshman) engineering students at the University of Pittsburgh Swanson School of Engineering. This paper is a student, not a professional, paper. This paper is based on publicly available information and may not provide complete analyses of all relevant data. If this paper is used for any purpose other than these authors’ partial fulfillment of a writing requirement for first year (freshman) engineering students at the University of Pittsburgh Swanson School of Engineering, the user does so at his or her own risk.

THE USE OF -FREE MULTIDIRECTIONAL ELEVATORS IN

Rachel Dancer, [email protected], Sanchez 3:00, Julia Jones, [email protected], Mandala 10:00

Abstract— With the continuing effects of urban migration, Kate Ascher, the Milstein Professor of Urban engineers, architects, and builders are being challenged to Development at Columbia University Graduate School of make cities denser and more efficient. By the end of the , estimates that elevator wait times in New York century, seventy percent of the world will live in cities [1]. City “ranging from 20 to 25 seconds are These challenges can be overcome by taller and more considered good, while those between 30 and 35 seconds are economical buildings. However, current elevator generally considered unacceptable” [9]. A twenty second wait impedes the efficient construction and use of skyscrapers. The time may not seem like a significant amount of time on paper, implementation of rope-free multidirectional elevator systems but in a nineteen-story office building (the average could solve these challenges by reducing elevator wait times, number in ), each second wasted can ultimately optimizing costs, and increasing energy efficiency. lead to a human traffic jam in a busy [10]. The crowding These systems, named MULTI, are powered by associated with high traffic areas leads to worker irritation and electromagnetic induction that causes magnetic levitation, aggression, and is often “associated with stress and affects which moves the elevator side to side as well as up and workplace satisfaction” [11]. As a result, it is recommended down [2]. This method removes limitations caused by , that faster and more efficient elevator systems be designed to which restrict building heights and slow down the elevator mitigate these problems. [3]. It also allows multiple elevator cars to fit into one shaft Elevator inefficiencies reach far beyond those who ride and move throughout the building in a loop. Users will them on a daily basis. As buildings grow higher, elevators must experience shorter wait times and owners can better maximize service a greater number and people. In most their available floor space [4]. These systems can also reduce skyscrapers, this means that a large number of elevator shafts a buildings electric bill by up to 60% [4]. and cars are required in the building. However, the installation In this paper, we intend to analyze how the MULTI of elevator banks has prominent impacts on the profitability Elevator compares to traditional elevator systems, and how it and usability of a . Ascher asserts that “each could be implemented in order to make the production and use additional bank of elevators reduces the floor area available for of skyscrapers cheaper, more efficient, and more convenient. rent or sale-thus pushing down the revenue potential for the building” [9]. As the number of elevators in a building increases, the square footage of each floor consumed by Key Words—Elevators, Linear Induction, Magnetic elevator shafts rapidly increases, while space available for rent Levitation, Skyscrapers, Transportation Engineering begins to dwindle. Ken Yeang, a renowned architect and ecologist, provides CURRENT ISSUES IN URBAN LIVING guidelines for acceptable space use in skyscrapers. He asserts that “net-to-gross floor area should not be less than 75%, while Sustainably Accommodating a Growing Urban 80% to 85% is considered appropriate” [13]. Net-gross-floor Population area (also known as space efficiency) is “simply defined as the ratio of NFA to GFA” [14]. NFA, formally known as the net The traditional elevator creates a variety of inefficiencies floor area, is the “actual occupied area not including for building users, building owners, and building designers. unoccupied accessory areas such as corridors, stairways, These unsustainable inefficiencies are both time wasting and , mechanical rooms and ” [15]. GFA, known as cost prohibitive, leading to buildings that inconvenience users gross floor area, is “the floor area within the inside perimeter and limit the designers and building owners. In a of the exterior of the building under consideration… conducted by IBM in 2010, the “cumulative time that office without deduction for corridors, stairways, closets, the workers spend waiting for elevators in the past 12 months thickness of interior walls, or other features” [15]. A totaled 92 years” across sixteen metropolitan areas in the visual representation of how a floor is broken into different [8]. areas can be seen in Figure 1. In this figure, the GFA is initially University of Pittsburgh Swanson School of Engineering 1 Submission Date 03.31.2018

Rachel Dancer Julia Jones divided between NFA and a structure area. This structure area resonance and lack of damping make elevators vulnerable to is where the space taken up by elevator shafts is categorized. damage caused by vibration. Rope-swing, a phenomenon that occurs when an elevator cable reaches its natural frequency, causes the elevator cable to vibrate quickly, resulting in unusual elevator movement and damages within the elevator shaft [3]. However, rope-swing does not affect many people in their daily life because of Newton’s 3rd Law, which states that an object at rest stays at rest until a force is applied [3]. This means that something needs to set the cord into motion. Waves in ropes of elevators in tall buildings can be induced by heavy wind or seismic movement. Wind is less of an issue because its effects are less extreme and more predictable [3]. Earthquakes are recorded to cause a lot of damage in mechanical elevators. Typical damage caused by rope swing in elevator shafts includes jamming of Figure 1. [15] elevator cables, deformation of rails, and derailing [3]. In This is a diagram that breaks down the total space on a 2011, surveys were done after the Chuetsu earthquakes in floor of a building into different categories, such as usable Japan to quantify damages, and it was found that “about 24% area, structural area, and mechanical areas. of the damage [in the Tohoku area] was due to ropes colliding with machinery or elevators becoming stuck.” [3]. This is Ultimately, increases in the number of elevators results significant because it demonstrates that cables on elevators can in decreases in NFA, leading to an overall decrease in space have destructive consequences if elevators are installed in efficiency. Because skyscrapers are “built to make money” [9], buildings in seismic zones. high space efficiency is crucial to maximizing rentable floor Since there are few viable solutions to this problem, space and making a skyscraper profitable. Civil engineers and engineers have found that the best way to fix the problem is to architects must strive to develop elevator systems that eliminate it completely. Instead of increasing the damping and maximize usable floor space while simultaneously attempting making a long tense rope, engineers use systems like sky to provide sufficient amounts of elevators for building users. lobbies to put limits on rope lengths to reduce the possibility of resonance. However, a solution that eliminates the rope Elevators as a Size Constraint of Skyscrapers completely could ultimately be a better, more cost-efficient method of fixing the resonance problem. Traditional elevators are one of the factors that put size limits on skyscrapers. While they are not the only factor, and CURRENT ELEVATOR TRANSPORTATION elements of design such as soil strength and building materials SYSTEMS have a strong effect on the height limit, elevators are a large component of deciding a height cap for a building [4]. Zoning Traditional elevators are cable driven, traction-based cars that traverse a track vertically to move people and cargo from floor In current skyscrapers, architects and engineers have to floor. The car is suspended by a steel cable that is connected created elevator transportation systems using zoning and sky to a and supported by a counterweight [16]. lobbies [17]. With zoning, each elevator does not have to stop All objects are vibrating to some degree all the time, but at every floor. As can be seen in Figure 2, each elevator is the nature of this design and the tension on this rope makes instead assigned a range of floors to service. This means that elevators vulnerable to hitting their resonance frequency. rather than one elevator lifting passengers going to a wide Vibration itself is not a bad thing. The issue occurs when range of floors, passengers are instead sorted into the elevator objects reach their natural frequency, or resonance, because the bank targeted to their destination. For example, in Figure 2, amplitude of the vibration is much greater [25]. The natural Elevator #3 is assigned Zone 3, meaning that it is responsible frequency of the rope is length dependent, but the length of the for transportation within Zone 3 (floors 10-15) and to Zone 3 cable is constantly changing [16]. This makes it hard to control from the ground floor. This significantly reduces the number whether or not a rope will reach its natural frequency [3]. In of stops an elevator must make on each ascent and descent. addition, elevator ropes have very low damping properties. Unfortunately, zoned elevators lose their efficiency in mega- Damping properties decrease the amplitude of a wave with tall buildings with upwards of sixty floors and high occupancy time [3]. Without damping, waves would continue oscillating amounts. This is because the number of zones necessary to indefinitely. There is no known way to increase the damping maintain efficiency increases as height rises, necessitating since the length of the rope is variable. Overall, the risk of more elevators. In addition, the number of occupants in a building grows with height, meaning more elevators will be

2 Rachel Dancer Julia Jones needed to service each floor in order to accommodate the increased population.

Figure 3. [17] This is a diagram that depicts how sky lobbies work in a building. Several elevators are given cables long enough to reach a certain floor. This floor, referred to as the has another bank of elevators, unconnected to the first set, that are responsible for transporting passengers to the higher floors of a building. Figure 2. [17] This is diagram depicts how zoning works in a building. EVOLUTION OF ELEVATORS LEADING UP Each elevator is assigned a zone to be responsible for. TO MULTI Each zone consists of several floors. In this figure, each zone is 5 floors. Although the writings of reveal that “the Greek mathematician created a primitive Sky lobbies, on the other hand, break up elevator elevator in 236 B.C.”, the elevator did not become integrated distances by creating separate elevator shafts at various points into common society until Elisha Graves Otis “invented a throughout the building. This shortens the length of the safety brake” in 1852 [7]. The safety break protected users elevator cables, significantly reducing safety issues associated from falling to the ground if the hoisting rope broke by with cables and resonance frequency. As explained by João ensuring that “a spring would operate pawls on the car, Valente in his Final Thesis for the Degree of Master in Civil forcing them into position with racks at the sides of the shaft Engineering, another “advantage of the sky lobby is the core and suspending the car in place” [7]. Otis’ safety brake optimization since all elevators do not have to serve the entry marked the beginning of the twentieth century’s global level. The upper local zones are stacked on top of one another, skyscraper race. so the elevator shafts, generally occupy the same "footprint" as Also, an important milestone in elevator history is the the local zones below” [17]. The stacking of elevators in the Paternoster Elevator, invented by Peter Hart in 1882 [15]. The sky can be seen in Figure 3. Although space optimization is an Paternoster Elevator, which is pictured in Figure 3, consists of important feature of elevators, particularly with respect to cost, several elevator cars moving in a continuous loop throughout the inconveniences that sky lobbies pose to building users must a shaft. The Paternoster system is “considered the most be acknowledged. Figure 3 demonstrates clearly that users effective transportation system”, but unfortunately it is “very who wish to travel to the top of the building are hindered from limited in height, speed, and safety”. Consequently, the system quick and easy transportation by a forced between two has been out of common use for several decades [15]. elevator systems. As a result, smooth and continuous transportation within the sky lobby elevator system is disjointed and inefficient.

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tracks, these new elevator cars can move up and down and left- to-right. This allows elevator shafts to deviate from the conventional vertical-only shaft, and expand into multi- directional pathways.

Figure 4. [18] This figure is a diagram of the Paternoster Elevator that would later become the inspiration for MULTI. The elevator cars in this system all fit into one shaft, and are demonstrated to rotate through a loop in the diagram.

OVERVIEW OF MULTI Figure 5. [21] More than 150 years later, the elevator has become an This image is a computer rendering of the integral part of everyday life. From office workers to arrangement of a MULTI system in a tall building. In the residents, many people rely on elevators to safely, image, blue elevator cars move throughout a continuous efficiently, and conveniently them. However, the orange elevator shaft. demand facing elevators has changed drastically since the first commercial elevator. Now, elevators serve hundreds of people HOW MULTI WORKS every day. In addition, the increasingly tall heights of skyscrapers have created a dependency on elevators. It is completely impractical to expect someone to climb hundreds Ropeless elevators work due to magnetism and linear of to arrive at their destination every day. Despite these motor technology. In a conference paper for the Council on changes, elevators “haven’t changed much in the past 160 Tall Buildings and Urban Habitat, Markus Jetter, the Head of years” [19]. To ensure reliable vertical transportation in the Product Development, and his partner, Stefan Gerstenmeyer, future, major innovations in elevator design are vital explained that the upward movement without a pulling force is Popularly coined as the “Willy Wonka Elevator”, made possible “by applying the technology of the MULTI is a new elevator technology that differs significantly magnetic levitation train, Transrapid, to the elevator industry,” from traditional elevators [19]. Inspired by the Paternoster [15]. The Transrapid is a high-speed train that uses magnetic Elevator system, MULTI was first prototyped in 1998 by Dr. levitation to hover above the track, which eliminates all Jessenberger at the University of Aachen [15]. Multi replaces friction, and it implements linear motors to motivate the ropes with linear motors to create “a successful circulating [19]. Magnetic levitation is a result of elevator system” [15]. MULTI has come a long way since its electromagnetism and linear motor technology. initial prototype in the late 1990’s. In 2014, ThyssenKrupp, a Applying the mechanisms behind the Transrapid to German industrial company well known for its innovative elevators means turning it on its side. This involves combining elevator such as AGILE, TWIN, and MRL, the levitation and propulsion devices because they do the same announced its plans to create a cable-less elevator technology thing. A big component of the MULTI elevator is the fact that [20]. it is not limited to a vertical track. The interlocking exchange As can be seen in Figure 5, MULTI is unique from system in the tracks of the elevator shaft does not disrupt the traditional elevator systems in that it consists of multiple magnetism in action. Electromagnetism, linear induction, and cordless elevators, all rotating through a single shaft. Because interlocking are the three main components of MULTI that it forgoes cords for linear motors and magnetic levitation

4 Rachel Dancer Julia Jones allow it to operate without ropes and run in multiple directions shows that this allows the car to support more mass while with multiple cars per shaft. moving at the same acceleration, as well as resisting a constant gravitational acceleration [24]. This is where handling capacity Electromagnetism and elevator materials come into play. It can support more people as well as the weight of the actual car if the strength of Magnets have properties that can give different types of the super conductor is strong enough. ThyssenKrupp has material the ability to produce a force, and that force can be reported that MUTLI can hold up to eight people in an elevator harnessed to do work [22]. This work can be used in propulsion car [15]. of ropeless elevators. This involves activating ferromagnets. Ferromagnets are metals that do not have magnetic properties on their own. Due their atomic structure, the electrons in the metals can easily align with an existing magnetic field. This phenomenon results in an induced magnetic field, given off by the ferromagnet, which makes it act like any permanent magnet would [23]. Electromagnets are made when a moving current is introduced to a ferromagnet. Adding an electric current to a ferromagnetic is another way to align the electrons and therefore induce a magnetic field. This is how electromagnets gain their magnetic force: a current is sent through a ferromagnet using electricity. Electromagnets have advantages over standard permanent Figure 6. [24] magnets because the strength is dependent on the strength of This image provides a visual for the equations and laws of the current, so the attraction has the ability to be turned on and physics described. In order from top to bottom, Ohm’s off as needed [22]. Electromagnetism is the interaction that Law, Biot Savart Law, and Lorenz’s Force Equation, and allows magnetic levitation to be possible. Newton’s 2nd Law are shown. In summary, induction can occur by introducing an existing magnetic field or an electric current. Both require a Linear Motor form of work, but adding a field involves converting mechanical energy, whereas running a current uses electricity Linear motors are used to move the cars through the as its form of energy. This concept applies to a bigger scale shafts of ropeless elevator. The engineers that created MULTI than elevators. Electricity powers lights and technology in have not directly revealed which type of linear motor they and buildings among other things [23]. used. With research, the only two plausible linear motors are The two methods of creating a force using an either a synchronous linear motor or a . electromagnet can be combined by using the concept of Multi had a patent released that said their linear motor does not superconductors. Superconductors are made by manipulating use iron for the permanent magnet, and linear synchronous electromagnets with the goal of giving them an extremely motors require permanent magnets and prefer soft iron. This strong magnetic field [22]. To do this, ferromagnets are cooled data point rules out linear synchronous motors. From this we to temperatures so extreme that they lose their electric can conclude that MULTI uses linear induction motors [26, resistance [23]. With little resistance, and a constant voltage 27]. from the supplier, the ratio of current increases [22]. Electromagnetic induction, as previously explained, is Using the laws of magnetism in Figure 6 to understand used to make an AC motor. AC motors use similar concepts to this phenomenon, it is clear to see that resistance has a large linear induction motors. Electrical energy is converted to impact on force. As proven by Ohm’s law, when the amount mechanical energy through the AC motor, and the mechanical of voltage supplied is constant, the resistance is inversely energy makes a mechanism spin. The type of mechanical proportional to the current [23]. Substitute Ohm’s Law into the energy needed for linear induction motors is different, but the Biot-Savart Law and the Lorenz’s Force equation to see that underlying principles are similar. Explained simply, linear current is directly proportional to magnetic field and force. So, induction motors are AC motors transformed from their rotary for instance, if the resistance in a ferromagnet was decreased shape to redirect the energy in a linear fashion [28]. Since the to be 100 times smaller, the magnetic force and field would energy is not limited to the rotary geometry, the motor can give increase to be 100 times larger than before the resistance a levitation effect. changed. This extra force is what makes magnetic levitation The technology that MULTI uses is comparable to the possible [22]. technology in trains, like the Transrapid [15]. Since the In the context of the elevator, this means that since the Transrapid moves strictly horizontally, it needs different engineers will use superconducting magnets instead of a mechanisms to provide levitation and propulsion. The primary standard electromagnet to control the car, they can control cars focus of the motor on the elevator is to make it follow the track using a greater force. Referencing Figure 6, Newton’s 2nd Law

5 Rachel Dancer Julia Jones so it can rise vertically. This combines the propulsion and levitation mechanism. Concepts of traffic engineering are required as well as The propulsion is not a continuous pushing force on the mechanics to explain how the interlocking system inside of elevator. For the car to move, it requires a combination of ThyssenKrupp’s MULTI elevator works. The hardware and positive forces to push the train forward and negative forces to software required to allow multiple cars to move in different pull the train forward. As shown in Figure 7, these positive and directions within the elevator shafts is complex. The algorithm negative attractions alternate. Magnets have north and south required for these cars to avoid collisions requires intel on the poles. Opposite poles attract and like-poles repel each other. routes these elevators need to take to get the most people to [26]. See Figure below. It depicts the technology used to make their destination as quickly as possible. The interlocking maglev trains run, but the same concepts can be applied to mechanism allows cars to change directions and takes care of elevators. the mechanical aspect of trafficking these elevators. [15] Interlocking is an important design aspect to touch on because it allows the elevators to break out of the strict verticality and move in any direction. To visualize interlocking, imagine trains changing direction at an intersection on a railroad. The rail rotates. This is usually with the help of a railway turntable, which is pictured in Figure 9. Trains drive to the center and have 360 degrees of rotation to navigate between [29]. In MULTI elevators, the system that changes the direction of the car is comparable to a railway turntable turned on its side. Referencing Figure 10, it can be confirmed that the systems are very similar in MULTI. On Figure 7. [25] either side of the elevator car, there are mechanisms in place This image explains that alternating poles on maglev to guide the car, and when they enter into an intersection where trains cause the forward propulsion. Elevator technology they can turn, the outside component rotates to allow it to move is comparable to trains. into the new direction. The car remains upright as it goes through the direction change. This mechanism allows long Linear motors are effective in creating magnetic distance horizontal travel by getting the car out of the one levitation in MULTI’s ropeless elevators. Figure 8 shows that dimension and providing it the option to move horizontally the motors in the actual device are on the inside the shaft, [15]. between the and the car. Because of the superconductors required to make magnetic levitation as strong as possible, it is extremely cold in that space. Pictured below is a top view of the elevator shaft of MULTI [23,26].

Figure 9. [29] This diagram is produced to explain how railway systems turn. A popular component of the interlocking system on Figure 8. [26] trains is the turntable design. Trains drive to the center This is the patent for the first maglev elevator, which was and have 360 degrees of rotation to navigate between. created by ThyssenKrupp in 1998. This is a top-view of the elevator shaft.

Interlocking

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estimates [35]. The likelihood of underestimation in the energy consumption of elevators makes the reduction in necessary power by MULTI elevators an even greater asset for building owners. Ultimately, the money saved in utilities costs from MULTI’s energy efficiency and the money generated by maximizing the amount of rentable space will increase the profit of building skyscrapers with more sustainable equipment.

BENEFITS TO BUILDING USERS

Figure 10. [30] The primary benefit MULTI poses to building users is a This image is an explanation provided by ThyssenKrupp decrease in wait times for elevators. As demonstrated in Figure to show how the turntable interlocking systems work. 11, the time it takes for a double-decker elevator car to arrive at its target floor gets substantially larger as building height increases. However, the time it takes for a MULTI elevator car BENEFITS TO BUILDING OWNERS to reach its target remains constant, and is always lower than the double decker elevator. This is because the time it takes for MULTI’s space and money saving features have the MULTI elevators to move to their target floor is not dependent potential to save building owners thousands of dollars. For on the height of the building, but rather on “velocity, number example, MULTI elevators have smaller shafts than traditional of stops, times, and highest reversal floor” [15]. Each elevators and can “increase a building’s usable area by up to MULTI elevator makes a constant amount of stops on every 25%” [31]. This is significant because “current elevator- ascent and descent, so there is no way to vary the time it takes footprints can occupy up to 40% of a building’s floor to get to each destination. space, depending on the building height” [31]. Because the purpose of skyscrapers is to generate profit through leases and rentals, every square foot of usable space is important to increasing profit. One issue that ThyssenKrupp does not address is that traditional elevators offer a large component of structural support to the core of tall buildings, and some engineers have concerns that changing the elevator will take away from the structural integrity of the building [32]. In skyscrapers, a large part of the structural support within the core comes from the elevator shaft [13]. This is because they are reinforced with steel to add the support to the building because it is a convenient location structurally. The concern lies within the possibility of taking out the continuous vertical elevator shaft. The selling point of MULTI is that users are not limited Figure 11. [15] to riding in the direction that tall buildings are erected. This This image depicts the amount of time it takes before an issue can be resolved by leaving the users the option to go all elevator arrives at its assigned floor at different building the way to the top of the building by keeping the continuous heights. The bars on the left show the times for MULTI, shaft, and adding horizontal options in addition to that. If this and the bars on the right show the times for double is ever not the case, engineers can make a skyscrapers core decker elevators. independent from the elevator. In addition, researchers at ThyssenKrupp have found that CURRENT AND FUTURE APPLICATIONS MULTI “requires dramatically lower peak power- as much as a 60-percent reduction when compared to conventional Immediately after ThyssenKrupp “first announced the elevator systems” [31]. This is significant because “elevators idea of a maglev elevator way back in 2014”, it began account for 3 to 8% of electricity consumption in buildings” developing a functional prototype of MULTI. [36]. In 2015, according to the Italian National Agency for New the first fully functioning 1:3 scale model of MULTI was Technologies, Energy and Sustainable Economic publicly unveiled at the Innovation Center in Gijón, Development [34]. Furthermore, researchers from SVM [37]. This model of MULTI, as seen in Figure 12, proved to Associates, an engineering consulting company, discovered the public that a ropeless elevator was possible, and laid the that “elevators were found to burn 16% to 36% more energy in for the larger and more complex prototype being real-world use” than they were predicted to consume in developed in Rottweil, .

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ThyssenKrupp is also making vigorous efforts to push MULTI into the public transportation sector in the future. The company hopes that MULTI can be used to integrate skyscrapers with underground metro stations in order to make entry and exit out of the station, as well as horizontal transportation within it, more efficient as population increases begin to create strenuous demands on stations [30]. MULTI would also make metro stations more accessible to and crutch users, who are often unable to conveniently enter, navigate throughout, and exit metros because of a lack of quick and conveniently located elevators.

PROBLEMS

Cost

Currently, no public information about the cost of a Figure 12 [37] MULTI elevator system has been published. Speculators such This image depicts “two ten meter shafts and four cabs” as Jamie Condliffe from the MIT Technology Review guess moving along a MULTI system in a loop like fashion [37]. that MULTI will “cost as much as five times more than a standard lift system” [36]. Despite high price estimates such as In 2017, ThyssenKrupp publicly unveiled its state of the Condiffe’s, MULTI’s ability to drastically improve space art elevator test center in Rottweil, Germany. Within the tower, efficiency and reduce energy consumption could create long “the MULTI system is installed in three of the twelve tower term financial benefits in buildings taller than three hundred shafts” [36]. The test tower, seen in Figure 13, is known as the feet, where elevator costs will already be sky-high. As prices Aufzug Testturm and is currently the “largest innovation are publicized, engineers and architects might have to sacrifice center for elevator technology in Germany” [38]. Because the long-term efficiency for affordability by installing cheaper and Aufzug Testturm also boasts the highest public viewing more traditional elevators. In order to truly become the platform in Germany at a height of 232 meters, the prototype elevator of the future, ThyssenKrupp may have to develop is the first opportunity for everyday citizens to interact with plans to reduce the costs of MULTI. MULTI [36]. Retrofitting

ThyssenKrupp needs to design an efficient, convenient, and cost-effective plan to install MULTI in preexisting tall buildings. Karen Kroll, a writer for Facilities Net, a popular facilities maintenance magazine, estimates that “elevator modernization could take nearly a year… [and that] the elevator will be out of commission for about 15 to 16 weeks” [40]. Furthermore, simply modifying traditional elevators with more up-to-date equipment such as cars, controllers, hoists, and door operators “can easily hit six figures” [40]. This implies that installing MULTI, a system already rumored to Figure 13 [38] “cost as much as five times as five times more than a standard This image depicts the ThyssenKrupp test tower lift system”, might not be a cost-effective technology to in Rottweil, Germany. This is where much of the testing implement in a pre-existing building [40]. However, there is for MULTI occurs. still possibility for ThyssenKrupp to develop cost-lessening methods to be used to retrofit preexisting tall buildings. The first customer lined up to install MULTI is OVG Real Estate, who wants MULTI to be implemented into its Jurisdiction brand new, eco-friendly building, the East Side Tower in [39]. The project does not have a completion date yet, Rick Sayah, the vice president of the elevator consulting but the future of MULTI depends on ThyssenKrupp’s ability firm Van Deusen & Associates, has expressed concerns about to successfully implement it into an actual building. the regulation of MULTI, especially when it is applied to the public transportation sector. Because MULTI will serve as

8 Rachel Dancer Julia Jones more than just a mere elevator in the public transportation 390: 164-191. 2017. Accessed 1.28.2018. https://ac.els- sector, its true role is blurred between an elevator and “a cdn.com/S0022460X16306228/1-s2.0-S0022460X16306228- vertical extension of the transit system” [30]. In addition, he main.pdf?_tid=642b2de2-0521-11e8-a064- worries that building “new safety codes around a technology 00000aab0f26&acdnat=1517250341_5ab2167be5127fae47c2 that’s so unlike the traditional elevator” will create difficulties 0fbaed454ca6 for the integration of MULTI into the transit industry [30]. [4] J. Miley. “The World's First Ropeless Multi-Directional Elevator Will Be Installed in Berlin.” Interesting Engineering. FINAL THOUGHTS 06-26-2017. Accessed 01.09.2018. https://interestingengineering.com/worlds-first-ropeless- Current urban living is in a fragile state because of the multi-directional-elevator-installed-in-berlin rapid increase in population growth coupled with the limited [5] A. Vassigh, T. Hove. “Urban Population Growth Between size in cities and the infrastructure that never accounted for this 1950 and 2030.” Citymayors. 2011. Accessed 2.21.2018. many people living in such high concentration. Living in cities http://www.citymayors.com/statistics/urban-population- is often more attractive than living further from work and intro.html action, and the number of city dwellers is increasing at a high [6] Division of the History of Technology. “Early Cars: Fact rate [4]. To adjust to growing urban populations, skyscrapers Sheet for Children.” The Smithsonian. 4.2001. Accessed need to be built higher in a more sustainable, economical, and 2.20.2018. https://www.si.edu/spotlight/early-cars user-friendly manner. An important factor in the creation of [7] L. Schumm. “Who Invented the Elevator?”. History.com. sustainable and user-friendly skyscrapers is elevators. 4.23.2014. Accessed 2.20.2018. Although elevators are an important element of the http://www.history.com/news/ask-history/who-invented-the- design, use, and of skyscrapers, their design has elevator not changed substantially in over 160 years [20]. They [8] “IBM Survey Shows Strengths, Gaps in U.S. Office consume significant amounts of a building’s energy, and Buildings.” IBM News . 4.29.2010. Accessed cannot be used continuously throughout buildings of a certain 2.23.2018. https://www- height to safety issues [4]. This has resulted in the creation of 03.ibm.com/press/us/en/pressrelease/30191.wss alternative elevator arrangements such as sky lobbies and [9] K. Ascher. “The Heights: Anatomy of a City.” New York, zoning. New York. Penguin Books. 2013. pp.32-96 In an attempt to mitigate the continuity issue of elevators [10] W. Hickey. “The Tall Apple: The Number of Stories in in skyscrapers, ThyssenKrupp created MULTI, a cable-less NYC Skyscrapers Might Floor You.” FiveThirtyEight. elevator. MULTI uses magnetic levitation instead of cables to 3.7.2014. Accessed 2.17.2018. move elevator cars in a loop similar to a train route. The https://fivethirtyeight.com/features/the-tall-apple-number-of- implementation of MULTI in a skyscraper has benefits over stories-in-nyc-skyscrapers-might-floor-you/ traditional elevators such as lower energy consumption, [11] “The Impact of the Physical Workplace on Performance: reduced elevator wait times, and increased profitability an Introduction.” Sodexo. Accessed 2.23.2018. through smaller elevator shafts. In addition, MULTI is http://www.qualityoflifeobserver.com/sites/default/files/impa designed to accommodate for future changes in the population ct-of-physical-workplace-on-performance.pdf of a building, meaning it can be renovated to add elevator cars [12] K. 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[18] Helfman. “Schematic Drawing of a Paternoster Elevator.” https://www.theatlantic.com/technology/archive/2017/07/can- Wikipedia. 10.1.2009. Accessed 2.28.2018. a-sideways-elevator-help-designers-build-taller- https://commons.wikimedia.org/wiki/File:Paternoster.png#/m skyscrapers/533544/ edia/File:Paternoster.png [31] J. Fischer. “ThyssenKrupp Premieres MULTI, World’s [19] L. Garfield. “This Real-Life Willy Wonka Elevator Zips First Rope-Less Elevator System.” ThyssenKrupp. 11.5.2015 Up, Down, Across, and Sideways.” Business Insider. Accessed 2.20.2018. https://www.thyssenkrupp- 7.21.2017. Accessed 3.1.2018. elevator.com.cn/en/cn/press/press-releases/press-release-data- http://www.businessinsider.com/elevator-of-the-future-2017- source-2-1378.html 7 [32] D, Budny. Conference Chair Meeting. University of [20] R. Stott. “ThyssenKrupp Promises to Revolutionize Pittsburgh Swanson School of Engineering. 3.22.2018. Skyscraper Design with Elevator Innovation.” Daily. 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Omori, "Simultaneous propulsion and levitation control of http://www.thyssenkrupp-elevator.com/en/press/press- linear induction motor in maglev system driven by power releases-72960.html source with frequency component synchronous with motor [39] “MULTI.” ThyssenKrupp. 2018. Accessed 1.20.2018. speed," 2013 15th European Conference on Power Electronics https://multi.thyssenkrupp-elevator.com/en/ and Applications (EPE), Lille, 2013, pp. 1-10. [40] K. Kroll. “Retrofitting Elevators for Energy Efficiency: http://ieeexplore.ieee.org/xpls/icp.jsp?arnumber=6634630 Pros and Cons.” Facilities Net. 12.17.2014. Accessed [29] “Turntables.” DCC Wiki. 06.14.2013. Accessed 2.27.2018. 3.29.2018. https://dccwiki.com/Turntables https://www.facilitiesnet.com/elevators/article/Retrofitting- [30] E, Nonko. “Can a Sideways Elevator Help Designers Elevators-for-Energy-Efficiency-Pros-and-Cons-- Build Taller Skyscrapers.” The Atlantic. 7.13.2017. Accessed 15512?source=part 3.25.2018. ACKNOWLEDGEMENTS

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We would like to acknowledge Thesaurus.com for always providing us with reliable word ideas throughout the duration of this paper. In addition, we would like to thank our conference chair and co-chair for taking the time out of their schedules to read and edit our paper. Finally, a massive thanks to those who helped teach us concepts about the physics concepts needed to write this paper.

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