Why did an ordinary collision accident evolve into a tragedy of 12 deaths and 37 injuries?

A major road traffic accident occurred in the Xianglufeng section of Longhushan, Yingtan, Jiangxi Province, killing 12 people and injuring 37 people. Experts involved in the accident investigation said that this may have been just a common collision accident. The cargo compartment panels were loose and tilted due to accidents, and finally embedded horizontally in the bus, causing heavy casualties. Then, why is the semi-trailer cargo compartment panel embedded in the bus? The accident investigation reveals the truth for you.

Accident case: Jiangxi Yingtan semi-trailer hit the bus and killed 12 people and injured 37 people

When the driver drives a heavy-duty semi-trailer to a corner of the 206 National Road in Yingtan, Jiangxi, the rear tail of the trailer crosses the center line of the road, and the left rear part of the carriage collides with the opposite bus. The car was scraped with the front of the heavy-duty self-unloading truck driving in the same direction, causing 10 people in the bus to die on the spot, 2 people died after being rescued, and 37 people were injured.

â–² Figure: Event Discovery

â–² Figure: Schematic diagram of the accident pattern, 1 for heavy semi-trailers, 2 for buses, 3 for heavy-duty dump trucks

After the accident, the Jiangxi Provincial People's Government established the “5·15” major road traffic of Yingtan City, which consists of the Provincial Safety Production Supervision Administration, the Provincial Public Security Department, the Provincial Supervision Department, the Provincial Department of Transportation, the Provincial Federation of Trade Unions and the Yingtan Municipal Government. The accident investigation team conducted a comprehensive investigation of the accident. The Beijing Zhongji Vehicle Judicial Appraisal Center was entrusted by the accident investigation team to assign technical personnel to participate in the investigation of the accident.

Cause of the accident: Why is there such a terrible traffic accident?

According to the survey, the semi-trailer driver occupies an overloaded vehicle whose driving safety performance does not meet the requirements. The corners and rainy days do not effectively control the safe speed. The tail of the vehicle crosses the road center line and enters the opposite lane, which is the accident. The main reason; the heavy-duty dump truck driver Huang Moumou driving unqualified overloaded vehicles, the corners and rainy days did not effectively control the safety speed, which is one of the causes of the accident; the bus driver Ren Moumou did not follow Driving practice regulates safe driving, and the safe speed is not effectively controlled in corners and rainy days, which is one of the causes of accidents.

At the time of the accident, the lock and the inserted column of the right rear fixed fence of the semi-trailer compartment fell off during the collision, and the cargo compartment panel was loose and inclined, and crashed into the bus compartment, which was the main factor causing the increase of casualties. . Then, why does the semi-trailer's fence fall off? Experts conducted further investigations into the accident.

Accident investigation: Why is the semi-trailer cargo compartment panel embedded in the bus?

After the semi-trailer hits the bus, why does the cargo compartment panel fall off and be embedded in the bus? Is it the quality of the vehicle itself, or is it improperly maintained? In order to answer these questions, the expert team conducted a detailed investigation on the scene of the accident, and extracted materials such as the left side of the semi-trailer and the hanging pin-spinning between the columns, and carried out laboratory analysis and inspection.

1

On-site inspection: insufficient length of pinch pin for cargo compartment, missing positioning bolt

After on-site inspection, it was found that six cargo compartment panels were installed on the left side of the semi-trailer, of which the first three slabs and slab pillars were basically intact, the last three slabs and slab pillars fell off, and the semi-trailer No. 4 cargo compartment slab Dropped on the road surface of the accident site, the 5th and 6th cargo compartment panels are embedded in the bus. As shown below:

â–² Figure: Cargo fence number diagram

â–²Picture: No. 5 and No. 6 cargo compartment panels are embedded in the bus.

In order to further understand the damage of the cargo compartment panel on the left side of the semi-trailer, the experts examined the cargo compartment 1-6. The preliminary test results mainly include the following aspects:

First, the hanging pin positioning bolts between the 1st and 2nd cargo compartments are missing, and the thick steel wire is used instead;

Second, the 4th, 5th and 6th cargo compartment panels exhibit different degrees of flexing, deformation and tearing;

Thirdly, the hanging pin positioning bolts between the 4th and 5th cargo compartments are missing, and the pinning is shifted to the No. 4 cargo compartment fence. The length of the pin and the No. 5 fence can be significantly shorter than that of the No. 4 column. The length of the plate can be contacted; the hanging pin and the fixing bolt between the 5th and 6th cargo compartments are slightly deformed; the rear hanging pin of the 6th cargo compartment is partially bent and deformed;

The fourth is that the left side of the cargo compartment panel has a fixed lock on the left side of the lock, and the other fixed locks are broken and fall off.

â–²Picture: No. 1 and No. 2 cargo compartment fences are missing pinning bolts, using thick steel wire instead

â–² Figure: No. 5 cargo compartment panel damage is the most serious, large area tear

â–² Figure: The pinning is shifted to the No. 4 cargo compartment fence. The length of the pin and the No. 5 fence can be significantly shorter than the length of the No. 4 fence.

â–² Figure: No. 4 cargo compartment panel lock tear, the rest of the locks are broken off

2

Laboratory inspection: no problem with the quality of the cargo compartment, but the problem of positioning bolts and pins

In order to further confirm the problems found during the on-site inspection, the experts extracted the left cargo compartment fence of the semi-trailer, the lock failure zone inspection material and the hanging pinning between the 4th and 5th cargo compartment panels. The laboratory continues the analysis of the next step.

Through the inspection of the sample of the failure zone of the left side of the semi-trailer, the mechanical properties of the fracture zone of the left side of the semi-trailer are in line with the national standard "Carbon Structural Steel" (GB/T 700- 2006) requirements; there are no fatigue cracks and old cracks on the surface of the fracture, and the fracture morphology is the normal ductile fracture formed by the impact; the metallographic structure of the fracture section is ferrite + pearlite, and the microstructure is normal. Metallurgical defects such as inclusions, segregation, etc.; welding defects such as weld cracks, unfused, and incomplete welds are not present at the weld. The results of the comprehensive laboratory analysis show that there is no quality problem in the material of the semi-trailer cargo box and the welding quality is normal.

â–²Fig.: The mechanical properties of the fracture zone of the left side of the semi-trailer are in line with national standards.

â–²Fig.: There is no early cracking on the surface of the fracture (left). The fracture morphology is the normal ductile fracture formed by the impact (right)

â–²Fig.: The metallographic structure of the fracture section is normal (left), there is no defect in the weld (right)

Laboratory tests were carried out on the hanging pin samples between the semi-trailer No. 4 and No. 5 cargo compartment panels. In particular, the "through-holes" on the upper and lower sides of the mounting bolts were further examined and found:

The upper and lower “through holes” of the positioning bolts are all in a regular circle, indicating that the positioning bolts are not installed at the “through holes” when the accident occurs. If the positioning bolts are installed, the upper and lower "through holes" will be pulled in the direction of the No. 4 fence when the accident occurs, and the positioning bolts that are gradually deforming are pulled during the separation of the cargo compartments 4 and 5. Deformation.

At the same time, it was found that the hanging pin has been deformed and cannot be moved in the pin bushing, indicating that the state in which the pin is displaced to the No. 4 fence is formed before the end of the accident. (Note: There are two possibilities for shifting the pin to the No. 4 fence. First, before the accident, the pinning position is not replaced by the thick steel wire. In the vehicle, the pin has been displaced to the No. 4 fence; Second, the accident occurred momentarily, even if the thickening wire was used instead of the positioning at the pinning point, but the thick steel wire was soft, and the pin was pulled and pulled off. In either case, it can be determined that the positioning bolt was missing before the accident.)

▲Fig.: “Through hole” is a regular circle, and the positioning bolt is missing before the accident

â–²Fig.: The pinning positioning bolt is missing, and the pin is shifted to the 4th cargo compartment fence.

Comprehensive on-site inspection and laboratory inspection can confirm that the pinning of the semi-trailer cargo compartment fence is missing, causing the left rear part of the carriage to collide with the opposite bus, and the pin is sold to the No. 4 cargo compartment. The displacement of the slats caused the No. 4 cargo compartment panel to lose its restraint and then fell to the ground. The No. 5 and No. 6 cargo compartment panels were loose, inclined and embedded in the bus.

Restore accident process: the semi-trailer cargo compartment fence falls off and is embedded in the bus, cutting off the left column

In order to reduce the accident, the semi-trailer panel will be inspected from the collision and falling off to the embedded bus. The experts will inspect the 4-6 cargo compartment fence, the cargo compartment panel hanging pin and the positioning bolt. The laboratory test results are analyzed and finally confirmed:

In the event of an accident, the cargo compartment fence on the left rear of the semi-trailer first collided with the bus and produced concave deformation and cracking. As the two vehicles continued to move relative, the collision zone extended to the cargo compartments 4 and 5. Between the boards, but because the hanging pin positioning bolts between the 4th and 5th cargo compartments on the left side of the semi-trailer are missing, the pinning pin cannot be fixed, and the pinning pin is displaced in the direction of the 4th cargo box fence, resulting in 5 The cargo compartment panel was not installed securely, which caused the rear part of the 4th cargo compartment panel on the left side of the semi-trailer to be unconstrained. During the road traffic accident involved, the left front part of the bus head collided to produce concave deformation and cracking.

As the two cars continue to move relative to each other, the No. 5 cargo compartment slid out from the pinning pin and loosened and tilted to the outside, colliding directly with the left column of the bus and being torn, eventually leading to the No. 5 cargo compartment fence The No. 4 cargo compartment fence is separated and detached as a whole, and the No. 5 and No. 6 cargo compartment panels are horizontally embedded in the bus. Except for the left rear tail column, the other columns were neatly cut off by the embedded cargo compartment panels, which eventually led to the tragic death of 12 people and 37 injuries in the bus.

â–²Picture: The bus column is neatly cut off by the embedded cargo compartment

The embankment of a thousand miles was destroyed by the ant colony. If the missing pinning bolts between the 4th and 5th cargo compartments on the left side of the heavy-duty semi-trailer are found and repaired in time, the driver does not drive the sick car, and the 12 lives in the bus are not Will stop shortly. The investigation conducted on this accident is to eliminate the problems behind the accident and eliminate hidden dangers from the source.

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