Abstract
The evolution, mechanisms, technological advancements, layouts, and social implications of escalators are present in the public space driven by engineering ingenuity. The early prototypes with refinement over time highlight the iterative nature of technological progress. Technology and standardization are specific, and intricate, and require many moving components, safety features, and operational parameters that are overlooked. The influence of social dynamics escalators has reconstructed pedestrian behaviors, social etiquette, and movement. Ongoing future developments aid in energy efficiency and safety integral for the public space.
Introduction
Have you ever wondered how the often-overlooked steps of an escalator work? Most of us have ridden an escalator before, whether in a shopping center, airport, or subway station. This machinery isn’t powered by some magical force; instead, it’s driven by engineering innovation for our everyday convenience. Escalators are one of the main modes of vertical transportation that has changed people’s lives. Its role in the public sphere is to ascend or descend people to new floors while also helping direct them to new places, promote efficient flow of pedestrians, and reduce foot traffic congestion. There have been drastic technological advancements to the escalator to become what it is today, so let us take a closer look at the inner workings, the assembly, and the history of the modern escalator.
The Beginning Prototypes
The first escalator-like machine was known as “revolving stairs,” and was designed by American inventor Nathan Ames, who received a patent in 1859 [1]. Its design featured an equilateral triangle of moving steps that carried passengers up one side and down the other, while its structure required people to jump on and off the steps to ride it [2]. Figure 1 shows the patented concept of Ames’s revolving stairs that was never built and remained only a concept.
Figure. 1 Nathan Ame’s patent [3]
It was not until American inventor Jesse W. Reno took the next step and invented the first working escalator, the “inclined elevator,” patented in 1892 [1]. Reno’s design introduced an incline angle using a single operating belt, along with combed plates at the top and bottom of the escalator for riders to easily step on and off the platform [3]. In 1896, Reno’s inclined elevator made its public debut at Coney Island, New York, where passengers rode his invention by leaning forward as they ascended.
Figure. 2 Jesse W Reno’s “inclined elevator” in Coney Island, NY [1]
Around the same time, in 1892, American inventor George Wheeler patented a moving stairway with a moving handrail and flat steps but never constructed it [3]. Figure 3 shows Wheeler’s patent, which introduced features like the handrail and flat steps, elements foundational to the modern escalator.
Figure. 3 George A. Wheeler’s Patent [4]
In 1898, Charles D. Seeberger bought Wheeler’s patent and worked at the Otis Elevator Company to develop the first step-type moving stairway [2]. Seeberger named his invention the “escalator,” derived from the Latin word scala (steps) and elevatus (rise) [2]. Figure 4 shows the implementation of the Otis escalator in a building. Initially trademarked by the Otis Elevator Company, “escalator” became a generic term due to its popularity in future applications. Seeberger and the Otis Elevator Company exhibited the flat-step escalator at the Paris Exposition in 1900, winning a Grand Prize and a Gold Medal [1]. In 1922, the modern escalator was perfected by combining Reno’s cleated steps and combed plates with Seeberger’s flat steps.
Figure. 4 Seeberger and Otis’s flat-step escalator [3]
The first retail use in North America came in 1896 with the installment of four of Reno’s inclined elevators in The Siegel Cooper Department Store [1]. Bloomingdale’s kept with the trend and in 1898 installed Reno’s inclined elevator of Wheeler’s version [1, 5]. In1902, Seeberger-Otis’s escalator commercialized the vertical transportation industry with its installation in Macy’s [1]. The steps were made of wood, providing customers with ease in moving through different stories. Over time, the wooden steps were replaced with metal,leading to the modern escalator.
The Building Parts and Mechanics
The escalator is a complex machine with multiple interconnected parts designed for smooth operation. Though the machinery is consistent in almost every model, each one varies based on location, potential traffic, and intended purpose. Figure 5 shows an escalator diagram divided into three main sections: exterior, interior, and steps.
Figure. 5 Escalator component diagram [2]
The exterior contains the handrail (a rubber grip moving at the same speed as the steps), the balustrade (sidewall of the escalator that supports the handrail and prevents passengers from falling), and the top and bottom platforms [2]. Both platforms protect machinery and provide the passengers with an area to step onto safely.
The interior contains the motor and drive gears powering the steps, a track guiding the step chain, and a truss, a metal framework that houses the entire machine and supports the tracks [2].
The steps consist of metal platforms linked together by a pair of step chains [2]. Each step has a pair of wheels: an upper set connected to the rotating chains being pulled by drive gears and a lower set following along the tracks [6]. These wheels allow the steps to protrude when moving along the track and flatten out at the landing platforms.
ASME, the American Society of Mechanical Engineers, standardizes safety protocols for escalators. Most escalator operating speeds are set at 100 feet per second (ft/s) (0.5 meters per second, m/s), which is about as fast as an iceberg, with faster speeds up to 125 ft/s (0.65 m/s), about half as fast as walking pedestrians [3]. The standard angle of inclination is set to 30° degrees with an allowable range between 27.3° and 35° [3]. The width of a step limits the number of people on a step: 15.75 in (400 mm) and 24 in (600 mm) supporting one person, and 32 in (800 mm) and 40 in (1000 mm) allowing for two adults, one adult with luggage, or one person with enough room for another to pass [3].
Outside of the U.S., there are grander, steeper, and faster escalators pushing the boundaries of the means of vertical travel. In Hong Kong, the Central Mid-Levels Escalators—the longest escalator in the world—spans a hillside consisting of a half-mile series of moving sidewalks with a vertical rise of about 443 ft (135 m) and lined by open-air markets [1, 7]. Comprised of multiple escalators, some sections adhere to the standard 30° inclination while others have a 17.5° inclination, falling below the standard [7]. The traveling speed is the standard 0.65 m/s, with a total journey time of around 20 minutes [7]. This mode of transportation reduces travel time by lessening the walking distance and foot traffic in the dense city.
Passenger capacity on an escalator depends on factors such as speed, angle, and step width, as well as location and expected foot traffic. Passenger capacity accounts for the passenger flow the escalator can withstand, which is separated into three sections: the entrance, ladder, and exit [8]. Understanding the capacity ensures that the escalator design suits its intended location, optimizes passenger transportation, and determines the necessary energy input to operate the machine efficiently. The equation for determining the passenger capacity is as follows:
N = (3600.P.V.cosΘ) ⁄ L
where N = number of persons moved per hour
P = number of persons per step
V = escalator speed (m/s)
L = length of step (mm)
Θ = angle of incline
For example, Figure 6 shows an escalator diagram with an inclination angle of 30° degrees operating at a speed of 0.5 m/s with a 400 mm step width, allowing for one passenger per step, which could transport 3,897 people per hour [9]. This capacity supports locations like airports and subway stations, which have high foot traffic. The more people using the escalator, the slower it may operate and the more energy it consumes.
Figure. 6 Escalator dimensions
Essential safety features are required for escalators. These include a safety brake button covered with a clear plastic top, a mechanism to brake when a foreign object jams into the escalator, handrails and extended balustrade for accessibility, and enough ventilation to dissipate heat. The escalator must also be reversible, such that it can ascend or descend depending on circumstances like busy foot traffic. Bristles line the inside edges of the balustrade near the steps to prevent foreign objects from jamming into the sides and alert people if their feet are too close to the edge. Comfort is another important aspect of user experience. Escalator speeds and incline could induce motion sickness if not calibrated correctly. The step and handrail speeds are synchronized, so any deviation will create discomfort for passengers. Excessive vibration of the handrail can also influence the passenger’s comfort and ride quality [10].
New Developments
Escalators consume large amounts of energy, accounting for 3-5% of a building’s overall energy use, which translates to approximately 900 GWh of electricity per year (data taken from 2010) [11]. That is enough energy to roughly power 90 billion LED lights. Commercial sector usage differs between retail sectors and transportation sectors, with transportation sectors working longer hours and are often larger consuming more energy. The step width determines the energy supply needed to power the motor and drive gears at the set speed. For example, a 24-inch step width requires a power supply of 10 horsepower (hp) [3], roughly equivalent to traveling 50–80 mph on a lightweight motorcycle.
Escalators operate at either a fixed speed or intermittent operation. Fixed speed escalators have two-speed operations controlled by a manual switch to optimize energy use for different traffic periods within a day [12]. Few escalators have intermittent operations, but there has been a push for more implementation. It can detect if there is no traffic and reduce the speed accordingly. Within that function, variable speed drive (VSD) allows the escalator to slow down and stop when a set amount of time passes after a passenger has left. The VSD can increase the amount of energy efficiency and consumption an escalator uses, saving up to 48% for incline escalators and 52% for decline escalators compared to a fixed-speed escalator [12]. The “Power Demand Cycle” for the VSD uses AI to to set the speed based on passenger detection, conserving power and reducing costs. Incorporating the VSD with a smart sensor at the motor will be able to detect not only passengers but also the status of certain parameters, like rotor speed, torque, and electrical anomalies, to report any faults within the machine to optimize its usage and efficiency [13]. Other sensors could detect common problems, such as uneven weight distribution due to passenger riding, out-of-sync speeds with handrails and track, as well as overheating from obstructed ventilation. Other detectable variables include radiation, broken light, electrical shock, or engine failure [14]. Sensor technology will be able to detect and potentially prevent hazards, ensuring the safety of passengers and indicating when escalator maintenance is required.
AI-based safety management software could further enhance safety detection capabilities. Machine learning technology, along withf video cameras, microphones, and signals transmitted from sensors,could monitor the status of the escalator. Using motion detection algorithms, the system could assess current conditions and predict future emergencies, potentially integrating with cloud and fog computation [14]. However, the infrastructure to support this software has yet to be constructed.
Technological changes could improve the quality and lessen the risks of the escalator. The comb plate, located at both ends of the landing platforms, prevents foreign matter from damaging inside components. Its shape reduces risk of foot clamping between the comb and minimizes the distance from the stair to the floor panel [15]. Being made of plastic enables easy breakage when a foreign object is jammed into it; however, this design could be an oversight and its fragility could result in a higher risk of lost combs and excessive maintenance repairs. The redesign as shown in Figure 9 of the comb will have the teeth be able to run up to overcome the defects [15]. Turning upward would avoid possible harm to the passenger and if foreign matter enters the comb teeth, the comb plate will be pushed by the steps through thrust. The benefits of this redesign would be faster removal time of foreign content, reusability, minimal installation process by maintenance, replaceable teeth section instead of the whole comb, and better protection for passengers [15].
Figure. 9 Escalator traditional comb
Layouts and Cost
The arrangement of an escalator depends on the client’s preference. Most are built in the center of a building to make the building itself feel expansive and invite people to explore the building. Figure 7 shows multiple arrangements, one style being the parallel arrangement when two escalators are staggered side by side creating an open appearance at upper landings creating space for ceiling decoration or high foot-traffic areas to promote selling merchandise. It is also the least congested layout for flow and has the greatest traffic handling ability due to its potential to easily direct the flow of traffic while deterring a queue at the landing platforms [3]. The multiple parallel arrangement is a similar concept as the first layout with several escalators side by side but is used in very high-traffic areas like subway stations or airports. The criss cross arrangement is the most popular because it utilizes floor space effectively, saving money and increasing convenience for customers to travel quickly. Despite its unique curvature structure,the spiral arrangement is the least popular and most difficult to maintain. Its restrictions include slower operating speeds and shorter structural height which can lead to a less efficient flow.
Figure. 7 Escalator layout [10]
All escalators are tailored to each building, making them an expensive feature. Consulting, designing, and installing an escalator can cost anywhere between $125,000 and $3,250,000 [16]. Those prices are for only one escalator and most to all escalators come in pairs. A consultant gathers information on its purpose, the expected foot traffic and the expected design layout. Add-ons to an escalator can include a security system, sensors, colors, and materials. It is designed and preassembled before shipping to its destination, taking vast amounts of time to perfect the design. The installation requires a team to safely and efficiently place the escalator into the space, typically requiring minor tweaking to accommodate the building. Operation and maintenance add expenses, and an escalator only has a lifespan of 10-20 years depending on the traffic level. The high expense of escalators, albeit less than that of elevators, should not overshadow the convenience they provide in people’s everyday lives.
Escalator Etiquette and Implicit Behavior
The interaction among people with escalators creates unspoken social rules people become accustomed to. Pedestrian movement, flow, and microscopic behavior all contribute to how a passenger rides an escalator. Many follow an implicit rule of standing on the right side of the step to allow people to pass on their left if the step is wide enough[17]. Single pedestrians may choose to walk more than people in groups, but when faced with an obstacle, like another person, they tend to wait behind them. In other cases, a single passenger might stop walking due to fatigue. Pedestrian organization occurs when groups of two or more people step onto the escalator, typically forming side-by-side, front-and-back on the right, or diagonal formations [17]. Figure 8 shows all variations of pedestrian standing layouts.
Figure. 8 Pedestrian organization on an escalator
It is advised not to walk on escalators for safety to prevent passengers from tripping on the steps. There are two misconceptions about walking on escalators: 1) that it would deteriorate the steps, and 2) that it increases the flow of traffic. Uneven weight distribution and speed from the predominantly-used right side can lead to deterioration of the steps and track, rather than walking itself [18]. Although walking on the left side would increase the flow of traffic during off-peak hours, during high-congestion cases, standing on both sides speeds up the flow of traffic because it allows more passengers on an escalator at one time [19]. Other factors such as weather, debris, and human interaction—like exposure to germs or waste—can also lead to escalator breakdowns and discourage passengers from holding the handrails [18].
Conclusion
The evolution of the escalator, from the revolving stairs to the modern machines seen today, represents a feat of engineering innovation. Technological advancements in newer designs focus on maximizing efficiency and safety while addressing energy consumption and environmental impact. The social dynamics arising from escalator usage, like escalator etiquette, demonstrate how these machines influence and shape our behavior and movement within public spaces. Continued investment in escalator design for future applications will be crucial, as escalators will continue to play a major role in facilitating vertical transportation and enhancing the efficiency of the public space.
Further Resources
Readings:
https://www.thyssenkrupp.com/en/stories/the-wondrous-world-of-the-escalator
https://www.cnn.com/travel/article/hong-kong-worlds-longest-escalator-system/index.html
Multimedia:
https://www.youtube.com/watch?v=UtkAJscxbZU
https://www.youtube.com/watch?v=Q2SpI6cjj_E
https://www.youtube.com/watch?v=vbsoO2c7gCM
References
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