LiDAR for Train Accident Prevention

On the morning of June 4, a train accident happens. The Guiyang-Guangzhou High-speed Railway D2809 train hit a mudslide at Rongjiang Station and went off the line, the driver Yang Yong on duty unfortunately died. According to the analysis of on-board data, the driver took emergency braking measures within 5 seconds once he found the line abnormal when the train traveled to the Yuezhai Tunnel before entering the Rongjiang Station, and the train taxied for more than 900 meters. This emergency braking finally ensured the safety of passengers on the train. The overall protection of the anti-collision wall and the track structure prevents the train from overturning and falling. After the train accident, 1 conductor and 7 passengers were quickly sent to the hospital for treatment. They have been properly treated and their lives are not in danger. The other 136 passengers on the train have been transferred to Congjiang Station by bus.

1. Train accident details

At about 10:30 on June 4, the D2809 passenger train from Guiyang North to Guangzhou South was traveling at the entrance of the Yuezhai Tunnel in front of the Rongjiang Station, when it hit a mudslide that suddenly slipped and intruded into the line. The No. 7 and No. 8 carriages were off-line, killing one driver, and injuring one conductor and seven passengers. The train driver on duty unfortunately died. The cause of the train accident is still under investigation.

The rescue team arrived at the scene about half an hour after the train accident. After the passengers were rescued, the seriously injured were immediately sent to the hospital for rescue. On June 5, after nearly 21 hours of efforts by rescue forces from all parties, the Rongjiang Station of the Guiyang-Guangzhou High-speed Railway Line resumed normal operations.

It is quite timely to take emergency braking measures within 5 seconds

After the train accident, according to onboard data analysis, Yang Yong, the train driver took emergency braking measures within 5 seconds when noticing that the line was abnormal when the train traveled to the Yuezhai Tunnel, and the train taxied for more than 900 meters. Besides, the overall protection of the anti-collision wall and the track structure prevents the train from overturning and falling. 

The probability of a similar accident occurrence is small 

Regarding the off-line train accident of the D2809 train, is there the possibility of monitoring and early warning, and whether there are any special forewarning measures to avoid such accidents?

Professor Li Yong from the Chengdu Institute of Mountain Hazards and Environment, Chinese Academy of Sciences analyzed that during the rainstorm season, the intrusion of mudslides and gravel is common on railways or highways located in mountainous areas. In this train accident, it was a high-speed moving train, and the accident site where the mudslide invaded happened to be at the entrance of the tunnel, resulting in an off-line train accident. But the probability of such a train accident occurrence is small.

2. Forewarning measures to avoid train accidents

According to Professor Li Yong, there are some monitoring, early warning, and forecasting measures for railway object invasion such as mudslides during the rainy season and flood season:

I. Local monitoring of rainfall and soil quality in key areas. However, due to the long railway and highway routes in the wild, and some relatively hidden mudslide ditches, it is impossible to monitor every point.

II. Block projects can be built. As far as debris flows are concerned, some block projects can be built along the ditch, such as a dam. It is necessary to determine whether the roadside may pose a threat to landslides, mudslides, or ordinary rolling stones.  

III. LiDAR has strong anti-interference ability, accurate ranging, and long-distance detection ability, which can ensure the safety of railway operations. LiDAR has been used in more and more rail projects:

A. Foreign Object Intrusion Detection during Train Running

Neuvition LiDAR can be mounted in front of medium-low speed trains such as trains, subways, etc. With a high resolution and an ultra-long detection range, it can monitor foreign matters ahead in real time during train running, and escort trains running safely. Aided by the precise perception of LiDAR and leading recognition algorithms, timely warning of foreign object intrusion is provided, and the accurate 3D map of the road ahead can be quickly constructed to timely determine the environmental condition required for the rail running, etc., to greatly increase the safety of train operation.

B.Rail Foreign Object Intrusion Detection

Foreign Object Intrusion refers to any target object that appears within the range limit of the safe operation of rail traffic and exceeds the safety range of its allowable overall dimensions, which further affects the normal operation of trains on this section of the road. In common rail traffic operation accidents, 25% of train derailments result from foreign object intrusion. Neuvition LiDAR Rail Traffic Detection Solution can judge whether there is a foreign object intrusion based on the given algorithm and real-time, high-density LiDAR point cloud data, to provide an early warning so that the rail department staff can take preventive measures.

C.Detection of Flatness of Rail Subgrade

As the foundation for trains, the rail subgrade directly bears the load of the train and has extremely high requirements for deformation and stability. Neuvition high-resolution, high-precision LiDAR can automatically monitor the subgrade deformation or abnormalities, such as uneven road surface, a hump of the track, pavement cracking, collapse, etc., it can process real-time recording of monitoring data, and then systematically analyze the health and safety status of the subgrade during the operation period.

With a resolution of up to 700 lines and an angular resolution of 0.01°, Neuvition LiDAR can effectively detect 600 meters, and meet the needs of faster measurement speed and higher measurement accuracy (up to ±2cm). Neuvition LiDAR uses a 1550nm laser which is a safe waveband for human eyes, can penetrate dense fog and dust, and adapt to harsh work environments. It meets the railway department’s requirements for vibration, radiation interference, different environmental temperatures, humidity, electromagnetic compatibility, etc.

In addition, when selecting railway lines, it is possible to bypass relevant areas by erecting viaducts and other methods. These problems will be noticed in the initial stage of line selection, and different techniques will be selected to prevent them according to the specific local topographical features and the characteristics of possible disasters.