escalator

escalator

[es-kuh-ley-ter]

Moving staircase used as transportation between floors or levels in stores, airports, subways, and other mass pedestrian areas. The name was first applied to a moving stairway shown at the Paris Exposition of 1900. Modern escalators are electrically powered, driven by chain and sprocket, and held in place by two tracks. As the treads approach a landing, they pass through a comb device; a switch cuts off power if an object becomes jammed between comb and treads.

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An escalator is a conveyor transport device for transporting people, consisting of individual, linked steps that move up or down on tracks, which keep the treads horizontal.

As a power-driven, continuous moving stairway designed to transport passengers up and down short vertical distances, escalators are used around the world to move pedestrian traffic in places where elevators would be impractical. Principal areas of usage include department stores, shopping malls, airports, transit systems, convention centers, hotels, and public buildings.

The benefits of escalators are many. They have the capacity to move large numbers of people, and they can be placed in the same physical space as one might install a staircase. They have no waiting interval (except during very heavy traffic), they can be used to guide people toward main exits or special exhibits, and they may be weather-proofed for outdoor use.

As recently as 2004, it was estimated that the United States had more than 30,000 escalators, and that 90 billion riders traveled on escalators each year.

Design, components, and operation

Operation

Escalators and their "cousins," moving walkways, are powered by constant-speed alternating current motors and move at approximately 1–2 feet (0.3–0.6 m) per second. The maximum angle of inclination of an escalator to the horizontal floor level is 30 degrees with a standard rise up to about 60 feet (18 m).

Modern escalators have single-piece aluminum or steel steps that move on a system of tracks in a continuous loop. Escalators are typically used in pairs with one going up and the other going down, however in some places - especially European stores and metro stations - there are no escalators going down, the escalators only go up. Some modern escalators have transparent side panels that reveal their gearings.

Escalators are required to have moving handrails that keep pace with the movement of the steps. The direction of movement (up or down) can be permanently the same, or be controlled by personnel according to the time of day, or automatically be controlled by whoever arrives first, whether at the bottom or at the top (the system is programmed so that the direction is not reversed while a passenger is on the escalator).

Design and layout considerations

A number of factors affect escalator design, including physical requirements, location, traffic patterns, safety considerations, and aesthetic preferences. Foremost, physical factors like the vertical and horizontal distance to be spanned must be considered. These factors will determine the pitch of the escalator and its actual length. The ability of the building infrastructure to support the heavy components is also a critical physical concern. Location is important because escalators should be situated where they can be easily seen by the general public. In department stores, customers should be able to view the merchandise easily. Furthermore, up and down escalator traffic should be physically separated and should not lead into confined spaces.

Traffic patterns must also be anticipated in escalator design. In some buildings, the objective is simply to move people from one floor to another, but in others there may be a more specific requirement, such as funneling visitors towards a main exit or exhibit. The number of passengers is important because escalators are designed to carry a certain maximum number of people. For example, a single-width escalator traveling at about 1.5 feet (0.45 m) per second can move an estimated 170 persons per five-minute period. The carrying capacity of an escalator system must match the expected peak traffic demand, presuming that passengers ride single-file. This is crucial for applications in which there are sudden increases in the number of riders. For example, escalators at stations must be designed to cater for the peak traffic flow discharged from a train, without causing excessive bunching at the escalator entrance.

In this regard, escalators help in controlling traffic flow of people. For example, an escalator to an exit effectively discourages most people from using it as an entrance, and may reduce security concerns. Similarly, escalators often are used as the exit of airport security checkpoints. Such an exit would generally be staffed to prevent its use as an entrance, as well.

It is preferred that staircases be located adjacent to the escalator if the escalator is the primary means of transport between floors. It may also be necessary to provide an elevator lift adjacent to an escalator for wheelchairs and disabled persons. Finally, consideration should be given to the aesthetics of the escalator. The architects and designers can choose from a wide range of styles and colors for the handrails and balustrades.

Model sizes and other specifications

Escalator step widths Energy usage
Size Width (Between Balustrade Panels), in Millimeters Width (Between Balustrade Panels), in Inches Single-step capacity Applications Energy consumption, in Kilowatts Energy consumption, in Horsepower
Very small 400 mm 16 in One passenger, with feet together A rare historic design, especially in older department stores 3.75 kW 5 HP
Small 600 mm 24 in One passenger Low-volume sites, uppermost levels of department stores, when space is limited 3.75 kW 5 HP
Medium 800 mm 32 in One passenger + one package or one piece of luggage. Shopping malls, department stores, smaller airports 7.5 KW 10 HP
Large 1000 mm 40 in Two passengers — one may walk past another Mainstay of metro systems, larger airports, train stations, some retail usage 7.5 KW 10 HP

Components

  • Top and Bottom Landing Platforms — These two platforms house the curved sections of the tracks, as well as the gears and motors that drive the stairs. The top platform contains the motor assembly and the main drive gear, while the bottom holds the step return idler sprockets. These sections also anchor the ends of the escalator truss. In addition, the platforms contain a floor plate and a comb plate. The floor plate provides a place for the passengers to stand before they step onto the moving stairs. This plate is flush with the finished floor and is either hinged or removable to allow easy access to the machinery below. The comb plate is the piece between the stationary floor plate and the moving step. It is so named because its edge has a series of cleats that resemble the teeth of a comb. These teeth mesh with matching cleats on the edges of the steps. This design is necessary to minimize the gap between the stair and the landing, which helps prevent objects from getting caught in the gap.
  • The Truss — The truss is a hollow metal structure that bridges the lower and upper landings. It is composed of two side sections joined together with cross braces across the bottom and just below the top. The ends of the truss are attached to the top and bottom landing platforms via steel or concrete supports. The truss carries all the straight track sections connecting the upper and lower sections.
  • The Tracks — The track system is built into the truss to guide the step chain, which continuously pulls the steps from the bottom platform and back to the top in an endless loop. There are actually two tracks: one for the front wheels of the steps (called the step-wheel track) and one for the back wheels of the steps (called the trailer-wheel track). The relative positions of these tracks cause the steps to form a staircase as they move out from under the comb plate. Along the straight section of the truss the tracks are at their maximum distance apart. This configuration forces the back of one step to be at a 90-degree angle relative to the step behind it. This right angle bends the steps into a stair shape. At the top and bottom of the escalator, the two tracks converge so that the front and back wheels of the steps are almost in a straight line. This causes the stairs to lay in a flat sheet-like arrangement, one after another, so they can easily travel around the bend in the curved section of track. The tracks carry the steps down along the underside of the truss until they reach the bottom landing, where they pass through another curved section of track before exiting the bottom landing. At this point the tracks separate and the steps once again assume a stair case configuration. This cycle is repeated continually as the steps are pulled from bottom to top and back to the bottom again.
  • The Steps — The steps themselves are solid, one-piece, die-cast aluminum or steel. Rubber mats may be affixed to their surface to reduce slippage, and yellow demarcation lines may be added to clearly indicate their edges. The leading and trailing edges of each step are cleated with comb-like protrusions that mesh with the comb plates on the top and bottom platforms. The steps are linked by a continuous metal chain so they form a closed loop with each step able to bend in relation to its neighbors. The front and back edges of the steps are each connected to two wheels. The rear wheels are set further apart to fit into the back track and the front wheels have shorter axles to fit into the narrower front track. As described above, the position of the tracks controls the orientation of the steps.
  • The Handrail — The handrail provides a convenient handhold for passengers while they are riding the escalator. It is constructed of four distinct sections. At the center of the handrail is a "slider," also known as a "glider ply," which is a layer of a cotton or synthetic textile. The purpose of the slider layer is to allow the handrail to move smoothly along its track. The next layer, known as the tension member, consists of either steel cable or flat steel tape. It provides the handrail with the necessary tensile strength and flexibility. On top of tension member are the inner construction components, which are made of chemically treated rubber designed to prevent the layers from separating. Finally, the outer layer, the only part that passengers actually see, is the rubber cover, which is a blend of synthetic polymers and rubber. This cover is designed to resist degradation from environmental conditions, mechanical wear and tear, and human vandalism. The handrail is constructed by feeding rubber through a computer-controlled extrusion machine to produce layers of the required size and type in order to match specific orders. The component layers of fabric, rubber, and steel are shaped by skilled workers before being fed into the presses, where they are fused together. When installed, the finished handrail is pulled along its track by a chain that is connected to the main drive gear by a series of pulleys.

Some handrail designs consisted of a rubber bellows, with rings of smooth metal cladding called "bracelets" placed between each coil. This gave the handrail a rigid yet flexible feel. Each bellows section was no more than a few feet long, so if part of the handrail was damaged, only the bad segment needed to be replaced. Bellows-type handrails fell out of favor in the 1970s, and since then most escalators so equipped have had them replaced with conventional fabric-and-rubber railings.

Conventions: standing and walking

An escalator user may choose to stand and ride at the speed of the escalator, or walk in the same direction to arrive faster. In many places — particularly on the longer escalators, used daily by commuters, found on rapid transit systems — passengers who stand customarily stay on one particular side of the escalator, leaving the other side free for walkers. The proper side for walking does not necessarily correspond with the passing lane in road traffic: passengers stand on the right and walk on the left on the London Underground as well as the Washington, Boston, San Francisco, Hong Kong, Seoul, Paris and Moscow subway systems; but in Singapore, Australia and New Zealand, they stand on the left. In Tokyo, Japan , riders stand on the left but Osaka riders stand on the right. On the Montreal Metro, while walking on escalators is theoretically forbidden, this rule is scarcely observed and not at all enforced, and passengers tend to stand on the right. In some countries there is no convention and people stand on either side randomly as they please.

A mnemonic for the U.S./British standing-and-walking convention is that stand and right each have five letters, while walk and left have four.

Safety

Safety is also major concern in escalator design. Fire protection of an escalator floor-opening may be provided by adding automatic sprinklers or fireproof shutters to the opening, or by installing the escalator in an enclosed fire-protected hall. To limit the danger of overheating, adequate ventilation for the spaces that contain the motors and gears must be provided.

Accidents and litigation

Accidents

There have been various reports of people actually falling off a moving escalator or getting one’s shoe stuck in part of the escalator; shoe laces are a particular hazard when untied and/or loose. A few fatal accidents in the recent past are:

  • Eight people died and 30 more were injured on February 17, 1982, when an escalator collapsed on the Moscow Metro. Wrongly set up emergency brakes were later blamed for the accident.
  • 31 people died after a fire, begun in the undercarriage of an M-type Otis escalator, exploded into the ticketing hall at King's Cross St. Pancras station in 1987.
  • On December 13, 1999, 8-year-old Jyotsna Jethani was killed at New Delhi's international airport. Jethani fell into a gaping hole that resulted from improper maintenance.
  • On June 15, 2002, Andrea Albright, a 24-year-old J.C. Penney employee in Columbia, Maryland, was critically injured while riding the store's escalator from the first to the second level. She somehow got her head caught between the escalator rail and a low ceiling. Albright died 10 days later of massive injuries to the brain from lack of oxygen. In 2005, her parents sued the property manager, two design firms, and the escalator company for $5 million.
  • Francisco Portillo, a Salvadoran sushi chef, died after being strangled when his sweatshirt caught in a Boston subway escalator on February 21, 2005 at Porter Square. He was allegedly drunk at the time.
  • A number of people have been injured on escalators while wearing lightweight plastic or foam sandals.

Lessons of the King’s Cross fire
The King’s Cross incident illustrated the demanding nature of escalator upkeep and the devices’ propensity to collect “fluff” when not properly maintained.

Since the station was part of a public institution (the London Underground) and there was a substantial casualty rate, the incident yielded vociferous public outcry as riders and victims’ families demanded the removal of all wooden escalators system-wide. In the official inquiry that followed, the Fennell Report, it was determined that the fire started slowly, smoldered virtually undetected for a time, then exploded into the ticketing hall above in a phenomenon known as the “trench effect.” This slow-burning fire, Fennell found, was allegedly kindled by a discarded unextinguished cigarette, which was shown in laboratory tests to be a more powerful ignition source than a lit match. In the escalators’ undercarriage, approximately of accumulated detritus acted as a wick to a neglected buildup of interior lubricants; wood veneers, paper and plastic advertisements, solvent-based paint, plywood in the ticket hall, and melamine combustion added to the impact of the calamity. Taking this particular situation as an example, one could easily speculate that any accretion of flammable fuels, cloth, or scraps (the “fluff” denoted by Fennell) could likewise lead to a devastating fire.

Consequentially, older wooden escalators were removed from service in the London Underground, though at least one set remains in operation, at Greenford Station. Additionally, sections of the London Underground that were actually belowground were made non-smoking; eventually the whole system became a smoke-free zone.

Litigation

In the 1930s, at least one suit was filed against a department store, alleging that its escalators posed an attractive nuisance, responsible for a child’s injury. These cases were almost always dismissed. Moreover, continual updating of escalator safety codes facilitated increased levels of consumer safety as well as a reduction in court cases.

Legislation and escalators

United States

Despite their considerable scope, two Congressional Acts, the Rehabilitation Act of 1973 and the Americans with Disabilities Act of 1990 (ADA), did not directly affect escalators or their public installations. Since Section 504 of the Rehabilitation Act included public transportation systems, for a few years, the United States Department of Transportation considered designs to retrofit existing escalators for wheelchair access. Nonetheless, Foster-Miller Associates’ 1980 plan, Escalator Modification for the Handicapped was ultimately ignored in favor of increased elevator installations in subway systems. Likewise, the ADA provided more accessibility options, but expressly excluded escalators as “accessible means of egress,” advocating neither their removal nor retention in public structures.

Codes and regulation

In the United States and Canada, new escalators must abide by ASME A17.1 standards, and old/historic escalators must conform to the safety guidelines of ASME A17.3. In Europe, the escalator safety code is EN115.

Key safety features developed over time

To enhance passenger safety, newer models of escalators are equipped with one or more of the following safety implementations, as per ASME A17.1 code:

  • Anti-slide devices — these are raised circular objects that often stud the escalator balustrade. They are sometimes informally called "hockey pucks" due to their appearance. Their purpose is to prevent objects (and people) from precipitously sliding down the otherwise smooth metallic surface.
  • Combplate impact switches — will stop the escalator if a foreign object gets caught between the steps and the combplate on either end.
  • Deflector brush — a long continuous brush made of stiff bristles runs up the sides of the escalator just above the step level. This helps keep loose garments and curious hands away from the dangerous gap between the moving stairs and the side panel.
  • Emergency Stop button — At each end of the escalator (in the London Underground also on the balustrade), a large red button can be pressed to stop the escalator. A transparent plastic guardplate (usually alarmed) often covers the button, to avoid the button being pressed accidentally, or for fun by children and casual vandals. Restarting requires turning a key.
  • Extended balustrades — allows riders to grasp the handrail before setting foot on an escalator, to ease customer comfort and stability/equilibrium.
  • Flat steps — the first two or three steps at either end of the escalator are flat, like a moving walkway. This gives the passenger extra time to orient him/herself when boarding, and more level time to maintain balance when exiting. Longer escalators, especially those used to enter a subterranean metro station, often have four or more flat steps.
  • Handrail inlet switches — located at the bottom and top of the unit. These sensors guard the opening where the handrail enters and exits the escalator. If something gets caught between the handrail and the opening, a hard fault is generated in the controller and the escalator shuts down.
  • Handrail speed sensors — located somewhere inside of the escalator unit. These sensors are usually optical, they are positioned to sense how fast the handrail is going. In case of a drive chain/belt breaking, in order to protect the drive and people on the escalator, if the sensor notices a speed difference between the handrail and the steps it will sound an alarm, wait for a couple of seconds, then stop the escalator. A hard fault is generated inside the controller, and therefore must be serviced by authorised personnel.
  • Level step switches — switches usually located at the top and bottom of the unit near the track hold-downs. These switches will detect an unlevel step before it approaches the combplate. This is to stop the escalator before the unlevel step crashes into the combplate, possibly preventing injury to a passenger.
  • Missing step detectors — located in various places (according to brand of escalator), this sensor can either be optical or a physical switch. No matter the type of device, the missing step detector will turn off the escalator when no step is found when one is expected.
  • Raised edges — the sides of the steps are raised slightly to discourage standing too close to the edge.
  • Safety instructions — posted on the balustrades at either end. Formerly, the only warning usually given was "PLEASE HOLD YOURSELF" or some variation thereof (and, in models that used now-rare smooth step risers, had such a message right on the step face). Now, a series of instructions are given (see below).
  • Sensor Switch — placed at the starting end of the escalator, the Sensor Switch will automatically start the escalator if a person is near the entry point. After some time, if no person is detected, the escalator will automatically stop.
  • Step demarcation lights — a fluorescent or LED light, traditionally colored green, is located inside the escalator mechanism under the steps at the boarding point. The resulting illumination between the steps improves the passengers' awareness of the step divisions. Some also use red lights at the exits, to warn passengers to step off quickly, and prevent passengers from using the wrong escalator.
  • Step demarcation lines — the front and/or sides of the steps are colored a bright yellow as a warning. Earlier models had the yellow color painted on; many newer steps are designed to take yellow plastic inserts.

Safe riding: official safety foundation guidelines

While some escalator accidents are caused by a mechanical failure, most can be avoided by following some simple safety precautions. The Elevator Escalator Safety Foundation is a major advocate for safe riding in the United States and Canada, and sponsors National Elevator Escalator Safety Week each year. Among their published suggestions for safe riding are the following points:

  • Always step out at the end of the stairs to prevent from falling.
  • Carry dogs up or down (or use the elevator).
  • Check for loose garments. These may include: long dresses, scarves, trench coats, or loose belts. Also, loose shoelaces are particularly notorious for getting caught in escalator machinery, so make sure that shoes are tied.
  • Children under the age of 7 should be accompanied by an adult when riding. Adults should hold a child’s hand.
  • Do not ride barefoot.
  • Do not use the escalator when transporting any large package or when pushing a device with wheels (moving sidewalks and ramps usually excepted — look for signs). This includes: baby strollers, baggage carts, hand trucks, or shopping carts. Also, the escalator should not be used by someone with a walker or on crutches.
  • Do not use the escalator if it is not in motion. ("Escalator steps are not the correct height for normal walking and should not be used in that manner. The risk of tripping and falling is greatly increased.")
  • Face forward.
  • Hold the handrail.
  • Keep footwear away from the side panels — especially shoes with traction.
  • Keep walking after exiting the escalator to prevent a pile-up.
  • Stand to one side of the escalator to allow others to pass you on wider escalators.

History

Inventors and manufacturers

Nathan Ames

Nathan Ames, a patent solicitor from Saugus, Massachusetts, is credited with patenting the first "escalator" in 1859, despite the fact that no working model of his design was ever built. His invention, the "revolving stairs," is largely speculative and the patent specifications indicate that he had no preference for materials or potential use (he noted that steps could be upholstered or made of wood, and suggested that the units might benefit the infirm within a household use), though the mechanization was suggested to run either by manual or hydraulic power.

Leamon Souder

In 1889, Leamon Souder successfully patented the "stairway," an escalator-type device that featured a "series of steps and links jointed to each other." No model was ever built. This was the first of at least four escalator-style patents issued to Souder, including two for spiral designs (U. S. Patent Nos. 723,325 and 792,623).

Jesse Wilford Reno, George A. Wheeler, and Charles Seeberger

In 1892, Jesse W. Reno, son of American Civil War notable Jesse L. Reno, and an 1883 engineering graduate of Lehigh University, patented the "Endless Conveyor or Elevator. A few months after Reno's patent was approved, George A. Wheeler patented his ideas for a more recognizable moving staircase, though it was never built. Wheeler’s patents were bought by Charles Seeberger; some features of Wheeler’s designs were incorporated in Seeberger’s prototype built by the Otis Elevator Company in 1899.

Reno produced the first working escalator (he actually called it the "inclined elevator") and installed it alongside the Old Iron Pier at Coney Island, New York in 1896. This particular device was little more than an inclined belt with cast-iron slats or cleats on the surface for traction, and traveled along a 25° incline. A few months later, the same prototype was used for a month-long trial period on the Manhattan side of the Brooklyn Bridge. Reno eventually joined forces with Otis Elevator Company, and retired once his patents were purchased outright. Some Reno-type escalators were still being used in the Boston subway until construction for the Big Dig precipitated their removal. The Smithsonian Institution considered re-assembling one of these historic units from 1914 in their collection of Americana, but "logistics and reassembly costs won out over nostalgia,” and the project was discarded.

Around May 1895, Charles Seeberger began drawings on a form of escalator similar to those patented by Wheeler in 1892. This device actually consisted of flat, moving stairs, not unlike the escalators of today, except for one important detail: the step surface was smooth, with no comb effect to safely guide the rider's feet off at the ends. Instead, the passenger had to step off sideways. To facilitate this, at the top or bottom of the escalator the steps continued moving horizontally beyond the end of the handrail (like a mini-moving sidewalk) until they disappeared under a triangular "divider" which guided the passenger to either side. Seeberger teamed with Otis Elevator Company in 1899, and together they produced the first commercial escalator which won the first prize at the Paris 1900 Exposition Universelle in France. Also on display at the Exposition were Reno's inclined elevator, a similar model by James M. Dodge and the Link Belt Machinery Co., and two different devices by French manufacturers Hallé and Piat.

Early European manufacturers: Hallé, Hocquardt, and Piat

Piat installed its "stepless" escalator in Harrods Knightsbridge store in 1895, though this date is in dispute. Noted by Bill Lancaster in The Department Store: a Social History, "customers unnerved by the experience were revived by shopmen dispensing free smelling salts and cognac. Hocquardt received European patent rights for the Fahrtreppe in 1906. After the Exposition, Hallé continued to sell its escalator device in Europe, but was eventually eclipsed in sales by other major manufacturers.

Major competitors and product nomenclature

In the first half of the twentieth century, several manufacturers developed their own escalator products, though they had to market their devices under different names, due to Otis’ hold on the trademark rights to the word “escalator.” New York-based Peelle Company called their models the Motorstair, and Westinghouse called their model an Electric Stairway. The Toledo-based Haughton Elevator company referred to their product as simply Moving Stairs.

Manufacturing mergers and buyouts: the playing field narrows

Kone and Schindler introduced their first escalator models several decades after the Otis Elevator Co., but grew to dominance in the field over time. Today, they and Mitsubishi are Otis' primary rivals.

Schindler now stands as the second-largest maker of escalators and elevators in the world, though their first escalator installation did not occur until 1936. In 1979, the company entered the United States market by purchasing Haughton Elevator; nine years later, Schindler assumed control of the North American escalator/elevator operations of Westinghouse.

Kone expanded internationally by acquisition in the 1970s, buying out Swedish elevator manufacturer Asea-Graham, and purchasing other minor French, German, and Austrian elevator makers before assuming control of Westinghouse’s European elevator business. As the last “big four” manufacturers held on to the escalator market, Kone first acquired Montgomery Elevator Company, then took control of Germany’s Orenstein & Koppel Rolltreppen.

Model development and design types

"Cleat-type" escalators

Jesse Reno's escalators did not resemble modern escalators too closely. Passengers' feet tilted upward at an angle, and the treads consisted of cleated metal (initially) or wood (later models). Reno worked on his own for several years, gaining success with installations from Toronto to Cape Town, South Africa. Similar units of the day by other manufacturers resembled conveyor belts more than moving staircases. For a time, Otis Elevator sold Reno's escalators as their own "cleat-type" escalators.

"Step-type" escalators

Seeberger's model, bought by Otis, clearly became the first "step-type" escalator, so called after its visual likeness to steps on a regular staircase. The company later combined the best aspects of both inventions (guiding slats and flat steps) and in 1921 produced an escalator similar to the type used today: they called it the "L-type" escalator. It was succeeded by the "M-type," the "O-type," and current models by Otis such as the "NCE-type" escalator.

Spiral escalators: from Reno to Mitsubishi

Reno, in addition to his notoriety for the first “practical” escalator in public use, also bears the unique distinction of designing the very first escalators installed in any underground subway system – a single spiral escalator in the London Underground in 1906, forgotten for several decades. Also the first fully-operational spiral escalator, Reno’s design was nonetheless only one in a series of several similar proposed contraptions. Souder patented two spiral designs (see above), Wheeler drafted spiral stairway plans in 1905, Seeberger devised at least two different spiral units between 1906 and 1911 (including an unrealized arrangement for the London Underground), and Gilbert Luna obtained West German, Japanese, and United States patents for his version of a spiral escalator by 1973. When interviewed for the Los Angeles Times that year, Luna was in the process of soliciting “major firms” for acquisition of his patents and company, but statistics are unclear on the outcome of his endeavors in that regard.

The Mitsubishi Electric Corporation was most successful in its development of “spiral” (more “curve” than true spiral) escalators, and has sold them exclusively since the mid-1980s. The world's first "practical" spiral escalator—a Mitsubishi model—was installed in Osaka, Japan, in 1985.

In use, a major planning advantage presented by spiral escalators is that they take up much less horizontal floor space than traditional units, which frequently house large machine rooms underneath the truss.

Etymology

Several authors and historians have contributed their own differing interpretations of the source of the word “escalator,” and some degree of misinformation has heretofore proliferated on the internet. For reference, contradictory citations by seven separate individuals, including the Otis Elevator Company itself, are provided below.

Name development and original intentions

Charles D. Seeberger trademarked the word "escalator" in 1900, to coincide with his device’s debut at the Exposition Universelle. According to his own account, in 1895, his legal counsel advised him to name his new invention, and he then set out to devise a title for it on his own. As evidenced in Seeberger's own handwritten documents, archived at the Otis Elevator Company headquarters in Farmington, Connecticut, the inventor consulted "a Latin lexicon" and "adopted as the root of the new word, 'Scala'; as a prefix, 'E' and as a suffix, 'Tor.' His own rough translation of the word thus created was "means of traversing from," and he intended for the word to be pronounced, "es-CAL-a-tor.

"Escalator" was not a combination of other French or Greek words, and is not a derivative of "elevator," which means “one who raises up, a deliverer” in Latin. Similarly, the root word “scala” does not mean "a flight of steps," but is defined by Lewis and Short’s A Latin Dictionary as the singular form of the plural noun “scalae,” which denotes any of the following: “a flight of steps or stairs, a staircase; a ladder, [or] a scaling-ladder.”

The alleged intended capitalization of “escalator” is likewise a topic of debate. Seeberger’s trademark application lists the word not only with the “E” but also with all of the letters capitalized (in two different instances), and he specifies that, “any other form and character of type may be employed . . . without altering in any essential manner the character of [the] trade-mark.” That his initial specifications are ostensibly inconsistent, and since Otis Elevator Co. advertisements so frequently capitalized all of the letters in the word, suppositions about the “capital ‘e’” are difficult to formulate.

Derivatives of ‘escalator’

The verb “escalate” originated in 1922, and has two uses, the primary: “to climb or reach by means of an escalator” or “to travel on an escalator,” and the secondary: “to increase or develop by successive stages; spec. to develop from ‘conventional’ warfare into nuclear warfare.” The latter definition was first printed in the Manchester Guardian in 1959, but grew to prominent use during the late 1960s and early 1970s.

Loss of trademark rights

In 1950, the landmark case Haughton Elevator Co. v. Seeberger precipitated the end of Otis’ reign over exclusive use of the word “escalator,” and simultaneously created a cautionary study for companies and individuals interested in trademark retention. Confirming the contention of the Examiner of Trademark Interferences, Assistant Commissioner of Patents Murphy’s decision rejected the Otis Elevator Company’s appeal to keep their trademark intact, and noted that “the term ‘escalator’ is recognized by the general public as the name for a moving stairway and not the source thereof,” observing that the Otis Elevator Co. had “used the term as a generic descriptive term . . . in a number of patents which [had] been issued to them and . . . in their advertising matter.” All trademark protections were removed from the word “escalator,” the term was officially genericized, and it fell into the public domain.

Primary uses and application

Department stores/shopping

As noted above, a few escalator types were installed in major department stores (including Harrods) before the Expo. Escalators proved instrumental in the layout and design of shopping venues in the twentieth century.

By 1898, the first of Reno’s "inclined elevators" were incorporated into the Bloomingdale Bros. store at Third Avenue and 59th Street. This was the first retail application of the devices in the US, and no small coincidence, considering that Reno's primary financier was Lyman Bloomingdale, co-owner of the department store with brother Joseph Bloomingdale.

Public transportation

The first “standard” escalator installed on the London Underground was a Seeberger model at Earls Court. Noted above, London's Underground installed a rare spiral escalator designed by Reno, William Henry Aston and Scott Kietzman for the Holloway Road Underground station in 1906; it was run for a short time but was taken out of service the same day it debuted. The older lines of the London Underground had many escalators with wooden steps (ca. 1930s) until they were rapidly replaced following the King's Cross fire, noted above.

Other applications

Factories and other industrial production environments

In 1905, the American Woolen Company’s Wood Mill in Lawrence, Massachusetts (then “the largest single worsted mill in the world”) utilized Otis' Seeberger-type “reversible” escalators to carry its workers between floors four times a day. The machines did not run all day: rather, escalators ran solely to transport employees to/from midday meals and in/out of the mill. In its advertising, Otis Elevator Company hailed this unconventional use for its unique benefits to both workers and owners: “The profitable and practicable feature of the Escalator, from the viewpoint of the owner, is the increased efficiency of each operator due to the elimination of stair climbing. However, in actual practice in a factory or industrial setting the high cost of escalator maintenance frequently outweighs the potential efficiency gained by transporting workers between floors on such equipment, so this application is less common than commercial and civic uses.

Military use

In San Francisco, an escalator at Hunters Point Naval Shipyard was used to convey personnel between the first and third floors. At the time of its construction in 1948, it was touted thus: "[it has the] highest lift of any industrial building in the world. It rises 42 feet.

Escalators were also utilized on aircraft carriers such as the , to transport pilots from “ready rooms” to the flight deck.

Extant historic escalator models

A number of historic escalators still operate across the globe. A few notable examples are:

Australia

Europe

North America

Escalators: superlatives

Longest systems

  • Central-Mid-Levels escalator: in Hong Kong, tens of thousands of commuters travel each work day between Central, the central business district, and the Mid-levels, a residential district hundreds of feet uphill, using this long distance system of escalators and moving walkways. It is the world's longest outdoor escalator system (not a single escalator span), at a total length of . It goes only one way at a time; the direction reverses depending on rush hour traffic direction.
  • Ocean Park, Hong Kong: a long escalator system connecting two parts of the Park, with an overall length of .

Longest individual escalators

Asia and Europe

The longest individual escalators in the world are found in the “metro” or “subway” systems in several cities in Central and Eastern Europe.

North and South America

Shortest escalators

Asia

According to Guinness, the shortest escalator in the world is in the Okadaya Mores shopping mall in Kawasaki, Japan. Its vertical rise is only .

North America

The shortest escalator in the United States is in the Westfield Garden State Plaza in Paramus, New Jersey. This is likely the shortest escalator pair in the world.

Notable spiral escalator installations

Asia

North America

See also

References

External links

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