A Next Generation Vertical Transportation System
ctbuh.org/papers
Title: A Next Generation Vertical Transportation System
Authors: Markus Jetter, Head of Product Development, thyssenkrupp Stefan Gerstenmeyer, Head of Elevator Traffic, thyssenkrupp
Subjects: Building Materials/Products Vertical Transportation
Keywords: Elevators Technology Vertical Transportation
Publication Date: 2015
Original Publication: The Future of Tall: A Selection of Written Works on Current Skyscraper Innovations
Paper Type: 1. Book chapter/Part chapter 2. Journal paper 3. Conference proceeding 4. Unpublished conference paper 5. Magazine article 6. Unpublished
© Council on Tall Buildings and Urban Habitat / Markus Jetter; Stefan Gerstenmeyer A Next Generation Vertical Transportation System
Markus Jetter, Head of Product Development & Stefan Gerstenmeyer, Head of Elevator Traffic and Group Control, ThyssenKrupp
The world’s first rope-free passenger elevator The propulsion and guiding system of multiple, In 1889, the Eiffel Tower in Paris opened system for high-rise applications enables the low-weight elevator cabins overcomes traditional with double deck lifts, becoming one of building industry to face the challenges of global rope elevators. Also, functional safety goes beyond the oldest and most well-known buildings urbanization. MULTI represents the realization current solutions. with an elevator system using two cars of a new elevator system offering several in one hoistway (Vogel, 1889). This was a great improvement, but at the same time, cabins in the same shaft, moving vertically and flexibility in the system is reduced, as the cars horizontally, permitting buildings to adopt The era of the rope-dependent elevator is now are in a fixed arrangement and loading and different heights, shapes, and purposes. It 160 years old. The basic principle of a traction elevator, having one car and a counterweight unloading happens on two floors, making represents a landmark revolution in the elevator in one hoistway, causes very high volume it difficult to synchronize; the car ready for industry and a new and efficient transport consumption in tall buildings. Floor space is the take-off has to wait for its partner to finish solution for mid- and high-rise buildings. Now, most valuable resource for building developers, loading and unloading. the long-pursued dream of operating multiple who want to build taller, using less space for cabins in the same elevator shaft is made elevators. Therefore, elevator engineers are Even triple-deck lifts have been considered to possible by applying the linear motor technology working on innovative methods to minimize take the next step towards better efficiency of the magnetic levitation train, Transrapid, to the percentage of floor space necessary to lift in the vertical transportation systems of tall the elevator industry. A traffic control concept for people in buildings. The idea of a circulating buildings. This would be a very big step, as a shaft-changing multi-cabin elevator system is elevator system was published more than 100 the sheer masses that must be moved in such systems increases tremendously. now included in vertical transportation planning. years ago (Condon, 1903).
102 Therefore, the next step aims to get back is still running at the University of Aachen. Beyond the optimized mechanical design flexibility while reducing masses in the Since then, the drive was considered to be of the car, all devices on the car necessary system. Over ten years ago, two independent feasible and today, the concept of a long for the elevator controller, electrical power, elevator cars travelling in the same hoistway stator synchronous linear drive will be used safety, guiding, and the interior of the cabin marked the next revolution in vertical for MULTI. are optimized in weight. Each cabin is transportation (Thumm, 2004). The TWIN capable of carrying eight passengers. was born and increased handling capacity The MULTI shafts are equipped with coil without limiting itself to certain floor units and multiple frequency inverters, and Guiding of Elevator Cars and Exchangers distances, travel sequences, and variation the magnet yokes are mounted on the cars. How can cars be guided in the shaft, of traffic demands. At the same time, the Only coil units that are directly involved including the horizontal movement between machine sizes and peak power loads could in moving a specific car are active, and the shafts? A backpack solution with be reduced compared to conventional multiple redundancies in the propulsion guidance and an integrated linear motor systems (Müller, 2014, Bass, 2014). system ensure high reliability. To build was the favored design out of dozens of an economical propulsion system, it is concepts. This also enables an optimized The Paternoster invented by Mr. Hart in 1882, important to limit the weight of cabins. design for an exchanger unit. Shaft and first installed in England in 1884 (Elevator elements rotating 90° enable a horizontal World, 2015), has been considered the most Lightweight Cabin movement using the same shaft elements. effective vertical transportation system, but Having the linear motor as a working During the rotation process of the shaft very limited in height, speed, and safety. propulsion system was not a breakthrough elements, the cabin is held in the upright However the general idea is still considered at the time, as the researchers found some position. Passengers can load and unload as the prototype for the ideal system. other missing links in the technology. A the cabin during the rotation process. This conventional car design, using steel as the guidance and exchanger concept enables Still the old dream remained, to have a primary material, would be far too heavy an exchanger unit at every position in the flexible number of several elevator cars in to use with an economical linear motor shaft. It also enables an extended horizontal multiple elevator shafts using a circulating propulsion system. New and optimized movement between more than two shafts system, based on the already existing design and manufacturing technologies, and longer travel distances. Paternoster (Elevator World, 1996). Traffic together with the use of new materials concepts and analyses based on these ideas like carbon composites, allowed for the An animated, virtual 3D simulation model of were done and published (Jappsen, 2002). But achievement of the car weight target. The car a car moving and circulating in two shafts, there were still open technical and economic was developed using topology optimization. questions at that time. Answers to the open questions needed to be found in order to realize a successful circulating elevator system.
Circulating Rope-Less Multicar Elevators In 2014, a rope-less elevator system called MULTI was unveiled (ThyssenKrupp Elevator AG, 2014), where multiple elevator cars use the same shafts and are able to change vertical shafts horizontally. The system has multiple, independent elevator cars circulating safely in multiple shafts (loops), propelled by linear motors.
Propulsion System Already, back in the 1990s, a linear motor Opposite: A circulating rope-less elevator system called MULTI. was designed by Dr. Jessenberger (Thyssen Source: ThyssenKrupp Aufzugswerke GmbH, 1998) and tested to Left: Light weight car of a rope-less circulating multicar elevator lift a rope-less elevator car. The prototype system propelled by linear motors (MULTI). Source: ThyssenKrupp
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Left: Cabin of a multicar system located at the exchanger unit. Source: ThyssenKrupp Bottom: Exchange process of a multicar cabin. Source: ThyssenKrupp Opposite: 3D model of MULTI at the High performance computing center Stuttgart (HLRS). Source: ThyssenKrupp
including shaft and exchanger design, gives Energy Buildings, which are already in the planning an early impression of the real system. What about energy? With the latest phases, in the region of one mile in height technology of linear drives it is possible to and with the goal of generating more Safety come very close to the equivalent energy energy than they internally need using solar, One of the most important issues is the consumption we know from permanent wind, and geothermal energy, cannot be technology of functional safety. Anti- magnet synchronous drives, used for made efficiently accessible without elevator collision and shaft door monitoring is based conventional traction elevators. systems that omit elevator hoist ropes. on more than 10 years of experience with Reducing the elevator footprint and number the TWIN safety solution. The safety concept The great advantage of the new system is the of elevator shafts generates potential energy of a circulating rope-less elevator system enormous reduction of peak currents by up savings by reducing the overall size and needs to go beyond known concepts. to 60% as the moving masses can be reduced external surface area of the building. Multiple cars and exchanger units are by a similar percentage. This allows for much monitored and mechanical safety devices better energy management in buildings to Current Traffic Concept and Analysis like a new and special braking system are achieve a smart grid. The regenerated energy A classical approach in high-rise buildings to developed for a rope-less system. Also, the from all the cabins travelling downwards will reduce the footprint of elevator equipment linear motor propulsions system is included not be fed back to the grid, but directly used is to divide the building into different in the safety concept to ensure additional internally by the system with fewer transition zones. Each zone is served by an elevator safety during operations. losses. Also, the number of cars in use within a group dedicated to a specific zone. If not all loop can be adapted to the traffic demand. elevators serve all floors in the building, core
104 “In 2014, a rope-less elevator system called MULTI was unveiled, where multiple elevator cars use the same shafts and are able to change vertical shafts horizontally. The system has multiple, independent elevator cars circulating safely in multiple shafts (loops), propelled by linear motors.“
105 space can be reduced in the upper floors latter provides higher individual flexibility requires the use of two cabins in one shaft, and low-rise elevators can be provided at and can be seen as elevator groups of mechanically coupled as double-decker lower velocities (Strakosch and Caporale, two zones, located within the same shaft. or two independent cars. Also, escalators 2010). Dedicating elevator groups to zones Regardless, there are limits in vertical connecting between the ground lobbies reduces the number of probable stops. Based transportation planning if no interzone may be necessary. Local groups can be on the roundtrip time calculations, reducing transfer floors are used (Müller, 2014). single cabin shafts or multi-cabin shafts. the number of stops reduces the roundtrip time (CIBSE, 2010) which can reduce the A state-of-the-art approach includes using Next Generation Vertical Transportation total number of necessary elevators. Elevator sky lobbies as transfer floors in the vertical Concepts groups for upper zones can have an express transportation plan. Local groups serving Shuttle and sky lobby arrangements using zone. Fast elevators are necessary to travel dedicated zones from a sky lobby are traditional single or double deck elevators long distances and achieve necessary stacked, and express shuttle elevators do have limits and disadvantages in shaft group handling capacities, waiting times, serve the passenger demand between efficiency. Still, only one or two cars or and times to destinations. Additionally, an the ground lobbies and the sky lobbies. cabins use a long single elevator shaft. installation with double entrance lobbies Vertical transportation concepts with In particularly tall buildings, elevators reduces the necessary footprints for interzone transfer floors can save elevator are getting faster to keep the journey elevators. Double-deck elevator cars and shaft space (Siikonen, 1997) and the shuttle time to a minimum and to provide an two independent cars in one shaft make it arrangements can be realized with single- adequate quantity and quality of service possible to get better shaft efficiency. The or with double-ground lobbies. The latter
106 L1 L2
Opposite: Comparison of different traffic concepts. Source: ThyssenKrupp Left: Options of simplified traffic concepts, including a circulating multicar system as a shuttle with a single ground lobby.
one B Source: ThyssenKrupp Z
S1 S2 one A Z
Exchanger
Car/cabin
with a minimum number of shuttle There are different options of simplified Spatial plots of one pair of cabins shows elevators. Limits in speed are related to traffic concepts, including a circulation how a pair of cabins move within the shafts. human comfort regarding differential ear multicar system such as a shuttle with a Travel in the upward direction is in a different pressure. Limits in travel height are related double ground lobby. There are two options shaft than the downward direction. Graph 1 to the maximum possible length of hoist for a sky lobby arrangement: A double shows the spatial plot of a circulating multicar cables. A circulating, rope-less multicar sky lobby (S3) and a pair of distributed sky with a pair of distributed sky lobbies like the elevator system eliminates the limits lobbies (S4). In case of a double ground arrangement in (S4). Graph 2 shows the spatial and disadvantage of traditional shuttle lobby arrangement, each ground lobby plot with two pairs of distributed sky lobbies elevators and also enables more flexible as well as the two highest sky lobbies will similar to the arrangement in (S5), which has arrangements. Some simple examples be equipped with an exchanger unit. This two double sky lobbies. A multicar loop can demonstrate options and flexibility. requires an exchanger unit somewhere in be assigned different zones with different the middle of the shafts. Similar to a single pairs of distributed sky lobbies. There are different options for simplified ground lobby configuration, different traffic concepts, including a circulating multicar loops can be assigned to different The arrangement of vertical transportation multicar system such as a shuttle with a and multiple zones in the building. That for vertical cities can be compared with single ground lobby. Different multicar means a multicar loop can serve multiple, horizontal transportation. The shuttle loops can be assigned to different zones in double sky lobbies or multiple pairs of elevators are like little intercity trains the building (S1). A multicar loop can serve distributed sky lobbies (S5), similar to connecting the main stations – the sky one or multiple sky lobbies, thus it can be solution (S2). lobbies. The local elevator groups are like assigned to multiple building zones (S2). local transportation via bus or underground Multiple multicar loops can be combined Local elevator group options for pairs of metro. The circulating inter-lobby elevator to a group serving the same zone(s)/sky distributed sky lobbies are similar to the system enables flexible arrangements in lobbies in the building (S2). single ground lobby arrangement. Additional vertical transportation concepts, is not options for local groups are possible with a limited to the shown examples and options, Local elevator groups can be stacked as single double sky lobby. Similar to local groups in and is not limited in height. car groups (L2) or groups of two independent double-decker shuttle concepts, a double- cars in a single shaft having distributed deck or two independent cars in one shaft Traffic Analysis lobbies for the lower and the upper cars (L1). can be used as a local group (L3). The traffic analysis described here is based This enables direct inter-zone traffic. on the work submitted/presented at the lift
107
S5
L3 L2 Left: Options of simplified traffic concepts including a circulation multicar system as a shuttle with a double ground lobby. Source: ThyssenKrupp Opposite: Comparison of a group of circulating multicar systems with a double deck group. Source: ThyssenKrupp one A2 Z
S4 one A1 Z
S3
Exchanger
Car/cabin
symposium Northampton (Gerstenmeyer and Peters, 2015).
The roundtrip time is based on velocity, number of stops, door times, highest reversal floor etc. and is a basic input parameter to calculate the interval and handling capacity of traditional elevators (CIBSE, 2010). The handling capacity of a circulating multicar system (loop) is based on the cycle time between two subsequent cars. The minimum possible cycle time defines the maximum possible handling capacity. The minimum possible cycle time Graph 1: Spatial plot of two cars with a pair of distributed sky lobbies. Source: ThyssenKrupp of two subsequent cars depends on door times, passenger transfer times, arrival and departure processes of cars, special exchanger unit delays and required safety distances between cars. It does not depend on travel height and velocity of the cars.
The real cycle time depends on the roundtrip time and the number of cabins in a loop. A longer roundtrip time because of higher travel height, additional stops, or slower velocity enables the usage of a higher number of cars in a loop. If the number of cars and the velocity is ideally adapted, the real cycle time can be the minimum Graph 2: Spatial plot of two cars with two pairs of distributed sky lobbies. Source: ThyssenKrupp
108 “The arrangement of vertical transportation for vertical cities can be compared with horizontal transportation. The shuttle elevators are like little intercity trains connecting the main stations – the sky lobbies. The local elevator groups are like local transportation via bus or underground metro.“
S3 D1
Exchanger
Multicar cabin
Double deck cabin
possible cycle time. So the handling capacity Traffic split: The handling capacity of the multicar system is a constant value not directly dependent • 80% incoming, 20% outgoing is constant. Starting with a travel height of on the roundtrip time. This also means it is Lobbies: about 200 m, it is going to be higher than independent of travel height and mostly • Double ground lobby the compared double-deck system. With independent of velocity. If a roundtrip or • Double sky lobby increasing travel height, the benefit of the a loop has a defined number of stops like circulating multicar system can be seen. The Shafts: shuttle arrangements, a maximum constant number of cabins required can be adapted • 4 double-deck shafts handling capacity can be reached. Two-way for the multicar system without additional traffic does not affect the upward direction • 2 multicar loops (= 4 shafts) shafts. The number of cabins is constant for handling capacity since the minimum Cabin size/passengers per cabin: the four double-deck shafts. possible cycle time is not affected by the • Double deck: 2 x 16 passengers traffic type. A traffic split of 50% incoming and • Multicar: 8 passengers For both systems, the rated velocity is 50% outgoing traffic does have double the increased with increasing travel height. The Space required: maximum handling capacity of pure traffic velocity of the multicar system is lower than • Double deck: 36 m² shaft space + in the up direction. The constant maximum the velocity of the double-deck. While the 18 m² waiting area handling capacity is the major benefit intervals of the four double-deck shafts gets compared to traditional traction elevators. • Multicar: 24 m² shaft space + 12 m² worse with increasing travel height, the waiting area interval of the multicar is constant as more Comparison of Circulating Multicar vs. Velocity: This is a variable depending on cars can be added. Double Deck travel height. Number of cabins: How is the performance of the circulating The average waiting time (AWT) and average • Double deck: 4 x 2 cabins multicar system compared to traditional time to destination (ATTD) of both systems double-deck elevator systems? The results • Multicar: variable depending on was compared, as illustrated in Graph 7. The of a simple case study demonstrate that. travel height and velocity average waiting time is derived from the Comparison will be made across different interval and cabin loading (CIBSE, 2010). travel heights (100 m, 200 m, 300 m and Graphs 3 through 6 show handling capacity, 400 m). The multicar loop excludes the chosen velocity, number of cabins and Since the interval of the multi car is constant, horizontal transportation of passengers for interval at the ground lobby of both systems the average waiting time is constant. this comparison. depending on travel height. Although the chosen velocity of the multi
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HandlingHandling Capacity Capacity (passengers/5min) (passengers/5min) VelocityVelocity (m/s) (m/s) 600600 1212 HandlingHandling Capacity Capacity (passengers/5min) (passengers/5min) VVelocityelocity (m/s) (m/s) 500500 1010 600600 1212 400400 8 8 500500 1010 300300 multimulti car car 6 6 multimulti car car 400400 doubledouble deck deck 88 doubledouble dec deck k 200200 4 4 300300 multimulti car car 66 multimulti car car 100100 doubledouble deck deck 2 2 doubledouble dec deckk 200200 44 0 0 0 0 100100 100m100m 200m200m 300m300m 400m400m 22 100m100m 200m200m 300m300m 400m400m Graph 3: Comparison of multicar vs. double deck depending on travel height: handling Graph 4: Comparison of multicar vs. double deck depending on travel height: velocity. capacity.00 Source: ThyssenKrupp Source:00 ThyssenKrupp 100m 200m 300m 400m 100m 200m 300m 400m 100m NumberNumber200m of of Cabins Cabins300m 400m 100m 200mInIntetervrvalal (sec) (sec)300m 400m 3030 4545 NumberNumber of of Cabins Cabins 4040 InIntetervrvalal (sec) (sec) 2525 3030 35454535 2020 30404030 2525 253525 1515 multimulti car car 35 multimulti car car 2020 2020 doubledouble deck deck 3030 doubledouble dec deck k 1010 15252515 1515 multimulti car car multimulti car car 10202010 5 5 doubledouble deck deck doubledouble dec deckk 1010 155155 0 0 100100 55 100m100m 200m200m 300m300m 400m400m 55 100m100m 200m200m 300m300m 400m400m 00 00 100m100m 200m200m 300m300m 400m400m 100m100m 200m200m 300m300m 400m400m Graph 5: Comparison of multicar vs. double deck depending on travel height: number of Graph 6: Comparison of multicar vs. double deck depending on travel height: interval. cabins. Source: ThyssenKrupp Source: ThyssenKrupp
car is less than the double-deck, the time to cause of many challenges in supertall In Summary destination of the multicar systems provides and megatall buildings and beyond: rope By taking all the best aspects of past better values. This is caused by lower average mass, rope sway, rope maintenance, rope achievements, including the Paternoster and waiting times and shorter passenger loading/ change…so it is better to be rope-less. the TWIN, and making them perfect with the unloading times. addition of the latest available technology Option: Construction Elevator of linear synchronous drives, lightweight Additional Advantages Another requirement from the construction design, a new component to exchange cars Building and Rope Sway side becomes more and more relevant for between shafts and move horizontally, and Tall buildings can vibrate at low frequencies the elevator industry: Why can’t you grow doing that safely under all circumstances (e.g., excited by strong winds). The building with the building and provide an operating using functional safety for the whole system, vibrations can excite the elevator hoist ropes, vertical transportation system in lower, it is possible to realize a circulating multicar especially if the building vibration is close to finished sections? system, the MULTI. Constant handling its natural frequency and coincides with the capacity and benefits in the elevator rope’s resonance frequency; large amplitudes It is quite typical that buildings grow footprint with increasing travel heights are of the rope sway may cause major problems during construction by one floor per day. characteristics of the system. No super-high- and damages (Kaczmarczyk, 2008). Traditionally, the elevator installation starts speed elevators are necessary to achieve when the machine room on top of the shaft good travel times and handling capacities. The taller the building, the lower the is ready and handed over to the elevator An uninterrupted flow of the number of frequencies which are critical for the ropes. This installation team. This is very late and other required elevator cabins enables short waiting causes elevator shut downs, especially in windy temporary vertical transportation systems times for a continuous passenger flow. MULTI cities like Chicago. Great efforts are required have to do the job in the meantime, at is the latest application of new passenger for rope sway risk mitigations in buildings with high cost and with a lot of time delay. transportation technology in vertical cities. natural frequencies between 0.1 – 0.2 Hz. Often, A rope-less system can grow with the the predicted frequency does not come into building in sections and provide the final being until after completion of the building, elevator group functionality and speeds. which can cause costly repairs. Additional cars can also be added to service the growing demand. The MULTI keeps Therefore, the elevator industry has to find pace with the speed and height of the final a way to omit hoist ropes. They are the root building height.
110 Waiting Time and Time to Destination 120
100
AWT multi car
80 ATTDmulti car
AWT double deck
60 ATTD double deck sec Poly. (AWT multi car)
40 Poly. (ATTD multi car) Poly. (AWT double deck)
Poly. (ATTD double deck) 20
0 100m 200m 300m 400m Graph 7: Comparison of multicar vs. double deck depending on travel height: average waiting time (AWT) and average time to destination (ATTD). Source: ThyssenKrupp
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