During this May Day holiday, the railway contact network was frequently searched for foreign objects and strong winds. In just 4 days, the power supply contact networks of the Beijing-Guangzhou High-speed Railway, Beijing-Tianjin Intercity Railway, Beijing-Shanghai High-speed Railway, Beijing-Harbin Railway Line, and Tianjin-Shanhai Line were "hit". These disruptive foreign objects include agricultural mulch, color steel plates, dust nets, etc. Why is the railway contact network so afraid of strong winds and "foreign objects"? Is the contact network really "fragile"? Is there any way to protect it? How to guard the "safety red line" along the high-speed railway? Railway professionals explained in detail to reporters.

Why is the high-speed railway contact network so afraid of strong winds and "foreign objects"?

He Chenglin, deputy chief of the contact network technology section of the Beijing power supply section, told reporters that electricity is the only power source for high-speed trains, and the high-speed railway contact network is an important part of the power source of the EMU. When working normally, the voltage of the live equipment of the contact network to the ground is 27,500 volts. In terms of material type, there are two types of foreign objects that affect the contact network: one is conductive foreign objects, such as tin foil, kite lines containing metal wires, etc. If one end touches the power supply line and the other end is grounded, it will cause the contact network to short-circuit and trip, causing the EMU to lose power; the other is insulating foreign objects, although non-conductive, but once it invades the dynamic envelope of the pantograph of the high-speed EMU, it can also instantly cause the pantograph to fail, making the EMU unable to obtain current from the contact network, resulting in the EMU being out of power.

He Chenglin introduced that once these foreign objects invade, there are generally two ways to solve them. For larger foreign objects, it is necessary to first stop the train on the line, shut down the contact network equipment, and traction power supply professionals enter the railway protection network. After taking corresponding safety measures, they are manually cleaned up. Especially large foreign objects often require the mobilization of contact network operation vehicles for auxiliary operations. For smaller and lighter objects, professionals can board the EMU and ride in the opposite direction to the fault point for manual operation. This type of fault is handled faster. In addition, if some particularly small foreign objects do not have a great impact on the operation, the pantograph will be lowered for operation, and the pantograph will be raised again after passing the foreign object point to reduce the impact on the operation.

Is the contact network really "fragile"?

The reporter learned that the contact network equipment itself is relatively stable, and the current problem is that there are too many external risk factors and they are unstable. He Chenglin gave an example, saying that the power supply section is responsible for the management of "lurking" light objects along the line. These light objects include dust nets on construction sites, plastic greenhouses in rural areas, plastic packaging bags in vegetable markets, and even a lot of kite lines are handled every year. "These foreign objects are extremely dynamic and difficult to control. After all, except for some tunnel sections, the railway is an open-air environment, and there will be various hidden dangers when passing through urban areas and villages."

It is reported that at present, the railway department mainly relies on human defense to deal with foreign objects, and regularly arranges personnel to patrol along the line and board locomotives for inspections of foreign objects. The reporter learned that scientific research units are studying the use of satellite image comparison and analysis to determine the new "lurking" light objects around the railway line, so as to make early judgments and increase the warning intensity.

How to guard the "safety red line" along the high-speed railway?

In fact, the railway department has clear "safety red line" requirements. According to the "High-speed Railway Safety Protection Management Measures" jointly issued by the Ministry of Transport and other seven departments, within 500 meters on both sides of the high-speed railway line, kites, balloons, Kongming lanterns and other floating objects shall not be raised, and offensive equipment such as crossbows, slingshots, and air guns shall not be used to engage in behaviors that may endanger the safety of high-speed railways.

At the same time, within this 500-meter range, the owners or actual controllers of lightweight buildings and structures such as plastic greenhouses, color steel sheds, billboards, and dust-proof nets on both sides of the line shall take reinforcement and protection measures, and promptly clean up construction and structural materials such as plastic films, tin foil, color steel tiles, and iron sheets to prevent high-speed railway safety from being endangered under windy weather conditions.

Ren Daxing, chief of the Comprehensive Management and Internal Security Section of the Beijing Engineering Section, told reporters that the railway divides objects that may affect the contact network into light and hard floating objects. The Engineering Section is responsible for managing "latent" hard floating objects such as color steel plates along the section. Since the issuance of the gale warning on April 30, there have been 50 to 60 people in this section alone who patrol on foot in different work areas every day. At the same time, they also patrol by "adding" locomotives to find problems in time and eliminate safety hazards in time.

Ren Daxing admitted that although the railway department has established a ledger for regular surveys of color steel sheds and other buildings along the line, many construction units have such buildings that change dynamically and the construction cost is also very low. "There was no inspection today, but it suddenly appeared tomorrow." Due to the weak "red line awareness" of relevant departments of some local governments and construction companies, reinforcement measures are often not in place, thus forming safety hazards that affect railway operations.

In addition to the color steel plates, the dangerous trees near some sections of the railway are also a concern for Ren Daxing. During daily inspections, some local management departments do not pay attention to and do not cooperate with the railway department. "After all, the railway is an enterprise. If the management measures are to be implemented, local government departments must pay attention and work together to strengthen law enforcement." Ren Daxing said. (Reporter Sun Hongyang)

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