Focus on the derailment of the Wenzhou train and see the train security system

After the train rear-end accident on July 23, train security was questioned by the masses: Why did the safety system fail at the most critical moment? Does the signal device work? In China, not to mention the 200km per hour passenger dedicated line, even the ordinary railway has an automatic blocking system that prevents rear-end collisions. The current causes of the accident are lightning strikes, train signal system failures, and driver human factors. The bigger question is whether, at the time, the locals described as "not seen for years" heavy rain and lightning convective weather, whether the catenary or signal line on the incident was actually caused by a lightning strike. There is still no clear answer.

The 30,000-kilometer electrified railway line in China has never been similar to a serious accident caused by a lightning strike. As a result, the signal was completely lost due to a lightning strike on the train line, and a casualty accident was a “low-probability event.” This cannot be proved at present. The rear-end collision incident belongs to such a small probability event.

The high-speed rail signal system mainly includes two products: one is the ATP (train automatic control protection system) installed at the front and rear of each train, and the other is the TCC (train control center system) based on the ground along the railway track. ATP controls the running of the train and accepts the stop operation signal. After ATP receives the signal, it cooperates with the ground TCC to ensure the safe and smooth operation of the high-speed railway.

On the Wenzhou-Wenzhou Railway, a CTCS-2 train control system has been implemented. This system can transmit operational permit information and line data to trains and is the central nerve that monitors the safe operation of trains. The CTCS-2 system includes the ATP, ATS, and ATO. In this accident, the ATP subsystem has become a widely viewed point of view.

The ATP subsystem can be equipped at both the train and the station. The ATP subsystem equipped on the train, if it works normally, can identify the front and running environment signals of the train. Based on this, it can judge whether it needs automatic deceleration or braking to force the train to stop. The ATP equipped in the station can also identify related signals, display it to the dispatcher in the station, and make judgments automatically. Therefore, even if the onboard ATP subsystem on the D301 train cannot work due to a lightning strike, the station can still issue an emergency brake command to the driver through the GSM-R system to avoid a rear-end tragedy.