What should you do if your phone falls on the subway tracks? First, don’t jump!

A netizen once asked sincerely, why are more and more people wearing sneakers on the subway now? Other enthusiastic netizens answered: Of course, it’s because they are afraid of being stepped on during the morning rush hour!

Sports shoes have become a good commuting partner for many subway workers. 丨Screenshot from a social platform

Yes, a pair of comfortable and well-fitting sneakers is indeed a great tool for squeezing into the subway. Sometimes, the movements required during a morning rush hour are no less than those of a breakdancing contestant, so sneakers are undoubtedly a better choice. Most importantly, sneakers are not as easy to fall off as other shoes .

A reporter once interviewed a Beijing subway station attendant and learned that at Xi'erqi subway station, an average of 20 shoes and more than 70 doll pendants fall on the track bed under the platform every month. In order to facilitate people whose shoes are squeezed off to go home, stations with huge passenger flow like Xi'erqi specially prepared slippers. In addition to daily items, the most expensive item that a station attendant has picked up on the track bed is probably a briefcase containing 5 real estate certificates.

Every time when many people are in a crowded subway, the thing they worry about most is that when the subway door opens, they lose their mobile phone and it falls through the terrible gap between the car and the platform. Losing a mobile phone is enough to make people want to jump down to pick it up (fortunately, most subway stations now have shielding doors to prevent people from being impulsive), not to mention losing 5 property certificates.

This is simply my nightmare! 丨Screenshot from a social platform

If you really drop something you carry with you, even if there is no shielding door, do not jump down. It is best to contact the subway staff in time. They have rich experience in helping people pick up things, and most importantly, they have some professional tools, such as long insulated clips specially used for subway tracks .

Similar to this insulated picking pliers. 丨Taobao screenshot

Insulation is key! Because if someone jumps off the subway platform rashly, he or she will not only face the danger of the train that may come at any time, but also the " third rail " under the platform - its electricity may electrocute people to death. Using insulated long clips to pick up things can effectively protect workers from being electrocuted by accidentally touching the third rail.

The third rail power supply is a power supply method used by many subways. The third rail is 1~2 conductive rails in addition to the two tracks on which the train runs. The conductive rails are usually located between or outside the two running tracks. Correspondingly, a collector device is installed on the subway train , which can contact the conductive rail and slide along it. The collector device looks a bit like a boot, so it is also called a " collector boot " or " receiving boot ".

Wuhan Metro Line 7 Changfeng parking lot, the yellow one next to it is the third track. 丨wiki

The third rail supplies power at a maximum voltage of 1500V, and there are also third rails with a voltage of 750V, which is very dangerous for people who accidentally come into contact with it. High voltage electricity can cause severe burns, muscle contraction, cardiac arrest, and in extreme cases, death. When road maintenance personnel are checking the condition of the rails, they must not work with live electricity.

In addition to the third rail power supply, some subway lines also use overhead wire power supply, which is powered by pantographs. Some lines use a mixed power supply method of third rail and overhead wire. The overhead wire power supply avoids the potential risk of people jumping onto the rails and getting electrocuted. However, the overhead wire is greatly limited by the tunnel space and has high construction costs. Among the existing urban rail transit, the third rail power supply type is more common .

So for safety reasons, don’t jump off the platform even if you drop any valuable belongings!

In most cases, something falling off the platform will not affect the normal operation of the subway, but if the fallen object triggers the subway's safety protection mechanism , it may affect normal operation.

The subway carries millions of passengers to their destinations every day, and the average passenger volume of Beijing subway on weekdays can reach 10 million. The precise operation of the subway is inseparable from the most advanced train control and signaling system.

Many subway lines now use semi-automatic operation, that is, the driver and the automatic train protection system (ATP) and the automatic train operation system (ATO) work together to ensure that the subway completes the journey smoothly.

The main function of the ATO device is to allow the subway to automatically start after receiving instructions, drive according to the instructions of the signal system along the way, and automatically stop when arriving at the station . It can also automatically accelerate or decelerate according to the signals provided by the automatic train control system (ATC) or ATP and other signal systems.

Shenzhen Metro Line 12 uses GoA4 level autonomous driving. The train can run without supervision and the doors can be automatically controlled. Passengers can watch the tunnel in front of the train from the position of the traditional train cab. 丨wiki

Only when the doors are all closed and ready will the train system issue a command to start the train. If there is an emergency such as the doors cannot be closed, the driver or staff will be needed to assist in handling it.

For example, if your mobile phone is squeezed off, but it does not fall completely onto the roadbed along the gap between the car and the platform, but is stuck in the gap of the car door, the subway car door may not be able to close.

This is really unfortunate.

The subway doors have an automatic obstacle detection function . When the door is blocked, it will automatically open a distance and then try to close again. This action will be repeated 3 times. If the problem is not discovered or handled properly in time, when the foreign object is still detected when closing the door for the third time, the door will be completely opened and wait for the staff to handle it.

If a door cannot be closed, the system will send an alarm to the control center . In this case, the subway will generally not be able to move out normally. If the problem cannot be eliminated in time, in serious cases, it may be necessary to clear the passengers and drive the empty subway car back to the maintenance station for repair.

Aren’t Bluetooth headphones the most common item dropped on the subway these days?

References

[1] https://www.sohu.com/a/274083387_348924

[2]http://guoqing.china.com.cn/2018-12/19/content_74291023.htm

[3]https://en.wikipedia.org/wiki/Third_rail

[4]https://zh.wikipedia.org/wiki/%E5%88%97%E8%BD%A6%E8%87%AA%E5%8A%A8%E6%8E%A7%E5%88%B6%E7%B3%BB%E7%BB%9F

[5]https://zh.wikipedia.org/wiki/%E5%88%97%E8%BD%A6%E8%87%AA%E5%8A%A8%E4%BF%9D%E6%8A%A4%E7%B3%BB%E7%BB%9F

[6]https://zh.wikipedia.org/wiki/%E5%88%97%E8%BB%8A%E8%87%AA%E5%8B%95%E9%81%8B%E8%A1%8C%E7%B3%BB%E7%B5%B1

[7]https://td.gd.gov.cn/dtxw_n/tpxw/content/post_4197288.html

Planning and production

Source: Bring Science Home (ID: steamforkids)

Author: Ziv

Editor: Wang Mengru

Proofread by Xu Lailinlin