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The second pedal at the entrance and exit of the escalator is often marked with a "Do Not Stop" sign.
In addition to avoiding crowds, this sign also reminds you to stay away from hidden "cannibal" entrances as soon as possible.
What's under the second elevator pedal? Is this one really dangerous compared to the others?
Whether it is a shopping mall or a subway station, there is a large section of silver-gray transition pedals between the escalator entrance and the original ground.
In general, this section of the transition zone consists of three parts: the leading plate, the middle plate, and the rear plate [1]. Among them, the front plate is the one closest to the elevator steps, and each step is submerged into the escalator under it. The middle and rear plates, which are immediately followed, are generally made up of multiple pedals spliced together [2].
Whether it is a leading plate, a middle plate, or a rear plate, the bottom is basically suspended / The answer is as follows
The "second pedal", which is a part of the middle plate, is divided into two types: "rectangular" and "T-shaped" [3].
The left and right ends of the rectangular middle plate are placed on the frame extending from the inside of the escalator, which has a large contact area with the frame, strong stability, and the center of gravity is located in the middle, making it difficult to flip [3].
Shandong Provincial Special Equipment Inspection and Research Institute has conducted a test: even if the connection between the rectangular middle plate and the front and rear plates is disconnected, and the testers step on it and jump, the rectangular middle plate will not overturn or lose stability [4].
But in comparison, the structure of the T-shaped plate is not so reliable.
The left and right sides of the horizontal area corresponding to the "T" are firmly attached to the frame of the floor slab, as are the rectangular central panels, while the left and right ends of the vertical part of the "T" are suspended[5].
The shaded part A at the left and right ends of the middle board is the part where the inner frame of the tread and the escalator overlap / The answer is as follows
Compared to the rectangular middle plate, the total contact area between the left and right sides and the bottom frame is smaller, and the center of gravity is not in the center of the pedal [3].
In other words, it is difficult for the T-plate to maintain its level on its own. If you remove the connection from the front and rear pedals, you don't need to jump on them, and the T-shaped midboard will overturn under the influence of its own gravity, or even "somersault" [5].
In addition to the contact between the two sides, the butt between the T-shaped middle plate and the rear plate is connected by a card slot structure, while the front plate is connected by a front and rear lap [1][6].
In general, the lap length between the T-plate and the front plate is reduced from the reserved 25 mm to 17 mm because of the need to leave 8 mm of front and rear displacement distance for the front plate to cope with foreign objects jamming into the pedal [7].
In addition, during the operation of the escalator, the front plate and the T-shaped middle plate will wear out of each other, and over time, the lap part will become unstable, and the T-shaped middle plate may disengage from the leading edge plate [2]. At this time, if someone has to step on it again, it will be bad luck.
After the T-plate is flipped, it is easy for people to lose their center of gravity and fall into the machine room below. As you can imagine, there are escalator steps that are constantly flipping downward, and wheels and machinery of all sizes are rumbling.
The internal mechanical structure of the machine room is extremely complex, and in order to ensure the safety of maintenance personnel, the escalator is generally ensured that only the maintenance worker can decide whether the escalator is opened or not during maintenance[8] / Diagram Worm Creativity
According to the regulations of the National Elevator Standardization Technical Committee, the machine room needs to have a maintenance space inside, with a standing area of not less than 0.3 square meters and a length of not less than 0.5 meters on the shorter side [9][10].
The hollow design under the pedal meets this requirement, but at the same time buries another safety hazard.
In order to avoid tragedy, various safety guards and alarms are usually set up inside the escalator entrance and exit and the computer room.
For example, pressing the red button at the bottom of the entrance and exit can cause an escalator to stop suddenly, or if the front plate is accidentally opened, manufacturers often put an additional layer of protection under the pedals or use bolts to reinforce the T-shaped center plate to prevent passengers from being swept into the machine room [8].
In addition, a baffle is provided between the overturned escalator steps and the area for maintenance personnel to prevent scratching of the steps [8].
The yellow cordon on each escalator step divides the dangerous clearance where foreign objects can be involved, and more than 50% of escalator accidents occur in the gap between relative movements[8] / Diagram Worm Creative
However, accidents can occur, and if you happen to fall into the area inside the baffle and the flipping steps, it can cause a serious accident [8].
An escalator "cannibalism" incident in Jingzhou, Hubei Province is a tragedy caused by many factors.
At the time of the incident, the T-shaped middle plate was detached from the front plate and flipped over, and the protective layer under the pedal was removed in advance due to temporary repairs, and a woman unfortunately fell into the engine room. [11] Coupled with the fact that she fell into the gap between the baffle and the flipping steps, and the passers-by around her failed to press the red emergency stop button in a panic, the woman was eventually caught up in the step system and died under mechanical squeezing.
After the accident, the "Rules for Supervision and Inspection of Elevators and Periodic Inspections - Escalators and Moving Walks" added a test item for pedal anti-overturning, which came into effect on October 1, 2017 [3].
The National Elevator Standardization Technical Committee has also issued a regulation that escalator pedals should be maintained and maintained every half month to investigate potential safety hazards [10].
For outdoor and semi-open-air escalators, prolonged exposure to wind and sun and rain erosion will accelerate the aging of the equipment[8] / Diagram Worm Creative
An accident occurs due to both the unsafe state of equipment and the unsafe behavior of people [12]. The unsafe state of the equipment is in the hands of the user and the maintenance unit, but the unsafe behavior can be controlled by everyone.
You know, the act of skipping the second board directly may be the source of the next tragedy.
[1] Chen Min. (2019). Discussion on the inspection and rectification plan of anti-rollover of escalator floor slab.Research on Quality and Technical Supervision (01),35-37.
[2] Han Lu, Zheng Jinyu. (2017). Discussion on the structural characteristics and risk prevention of escalator entrance and exit cover.China Special Equipment Safety (08),65-67.
[3] Yang Xu. (2019). On the inspection of escalator maintenance cover plate and floor plate.China Elevator(07),67-70.
[4] Niu Zhaoping, Wang Xinyu, Hou Chong, Li Deshan. (2015). Safety analysis of escalator and moving walk floor slabs.China Special Equipment Safety (09),75-77.
[5] Huo Nannan. (2016). Safety analysis of escalator and moving walk floor slab.Science and Technology Wind(12),94.
[6] Qian Binhua, Lu Juliang, Hu Pengfei. (2018). Analysis of the reasons for the flipping of escalator floor slab and suggestions for improvement.China Elevator(15),65-66.
[7] Zhong Xugen. (2015). Analysis of the reasons for the flipping of escalator floor slab and suggestions for improvement.China Special Equipment Safety(11),74-76.
[8] Shi Xinfang, Jiang Qingdong, Li Chunlei, Rao Meiwan, Chen Yanying. (2014). Escalators. China Machine Press.
[9] National Elevator Standardization Technical Committee. (2011). GB 16899-2011.General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of the People's Republic of China.
[10] National Elevator Standardization Technical Committee. (2012). TSG T7005-2012.General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of the People's Republic of China.
[11] Jingzhou Emergency Management Bureau. (2015). Jingzhou "7.26" elevator safety production general accident press speech.
[12] Zhang Yanbin. (2023). Analysis and preventive measures of escalator extrusion risk points.Labor Protection(09),90-92.
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