Text/China Communications Communications First Highway Survey and Design Institute Guo Tengfeng
▲At around 15:00 on December 18, 2021, the cross-bridge bridge deck overturned at the intersection of G50 Shanghai-Chongqing Expressway and Daguang Expressway Ezhou Huahu Interchange.
Recently, Hubei's "Investigation Report on the "12·18" Larger Bridge Deck Rounding Accident of the Huahu Interchange D Ramp" (hereinafter referred to as the "Report") was officially announced. After carefully studying the Report, the author has sorted out the key points of accident process and cause of accidents that everyone is generally concerned about. At the same time, he will accurately understand the content and conclusions of the Report, and a brief interpretation of the nature of accident units, the differences in over-limit transportation and ordinary freight management.
1. Accident overview
At 15:30 on December 18, 2021, a large over-limit transport vehicle group (the total mass of trucks and cargo is 521.96 tons) that transports large converter transformer (the total mass of trucks and cargo is 521.96 tons) was encountered when passing through the D ramp of Huahu Interchange of Shanghai-Chongqing Expressway in Ezhou City, Hubei Province; the accident vehicle group took risks and drove through without dissuasion. After deviating from the longitudinal center line of the bridge, the bridge overturned and hit the passenger car driving normally under the bridge. Then the accident vehicle group, cargo and bridge deck personnel all fell from the bridge. The accident caused a total of 4 deaths and 8 injuries, and the direct economic losses of 30.1782 million yuan were made.
▲Figure 1 Schematic diagram of the vehicle group involved in the accident
▲Figure 2 Schematic diagram of the vehicle group involved in the accident
2. Accident qualitative
The report clearly states that the "12·18" bridge deck rollover accident in Ezhou City Shanghai-Chongqing Expressway (G50) Huahu Interchange D ramp is a major production safety responsibility accident .
3. Direct cause of the accident
The report clearly states that the direct cause of the accident is: the carrier illegally over-limit transportation, deliberately evades supervision, the personnel involved take risks to transport, violate the regulations that large-scale transport vehicles should drive in the middle when passing through the bridge, and the center of gravity deviates from the bridge center line to 3.13 meters. The overturning effect exceeds the bridge's anti-capsulation ability, causing damage to the bridge support and constraint system, and the anti-capsulation reinforcement and pulling device to fail, resulting in the overall overturning of the bridge.
▲Figure 3 Schematic diagram of the horizontal position of the vehicle group involved in the accident
▲Figure 4 Schematic diagram of the accident site
4. Analysis of the cause of the accident
The accident investigation team reviewed the information, on-site inspection, physical evidence identification, video analysis, witness inquiry, field investigation, simulation experiment, theoretical calculation and analysis, and after evaluation and demonstration by experts, the bridge maintenance was normal, in good condition, traffic under the bridge was normal, there was no impact or collision bridge structure phenomenon, and no blasting or explosion occurred under the bridge. The construction quality problems of the bridge body and the overturned steel box girder were ruled out, and the impact of the accident-related vehicle group entering the beam section at a low speed on the curved beam section was ruled out, and factors such as geological disasters, severe weather, and earthquakes were ruled out.
5. Causes of accident management
1) Causes of the company involved in the accident
is that illegal over-limit transportation causes potential accident hazards.
The second is to use false materials to illegally obtain large transportation permits to drive on the road.
Third, the relevant units and personnel have weak safety awareness.
Fourth, the internal management of the enterprise is chaotic, security management is in a formal way, and security supervision is missing.
2) Reasons for regulatory authorities
is that large-scale transportation license approval is not strict.
Second, there are long-term management loopholes at the entrance of the expressway and the inspection is not strict.
Third, there are blind spots in the comprehensive supervision linkage work along the way.
6. Some facts investigated and determined by the report
The following lists some facts related to the direct cause of the accident according to the content of the report:
) The total mass of the vehicle cargo in the accident involved is 521.96 tons (the mass of the cargo body is 291 tons), the maximum axle load is 32.1 tons, the total length of the vehicle unit is 67.67 meters, and the load axle load exceeds the limit standard, which is an illegal over-limit transportation .Before departure, the carrier uses the method of "small to replace the big" and "small to replace the prince" to deceive with false materials to "overlimited transport vehicle pass" .
) During transportation, the accident-related vehicle crew did not drive according to the permitted route and did not implement escort measures as required.
- ) Before passing to the bridge section of the incident, it did not actively report to the relevant departments. was forced to pass through when it encountered bridge deck maintenance and construction.
- ) The accident-related vehicle crew did not stipulate that they would drive in the middle of the bridge deck and deviate from the longitudinal center line of the bridge , resulting in the bridge instability and overturning.
7. The bridge design, construction and management conditions specified in the "Report"
) The units of accident bridge design, construction, supervision and other units have the corresponding qualifications and meet the conditions for undertaking relevant business; the engineering design, approval, acceptance and other materials are complete, and the engineering construction procedures are in accordance with the law.
) The design and construction unit of the ramp span bridge anti-capillary reinforcement project has the corresponding qualifications and meets the engineering construction requirements. The engineering reinforcement project design documents and engineering contract information are complete. ) The standards and specifications used in the design before bridge reinforcement meet the requirements at the time; all kinds of inspection and testing materials and evaluation materials for bridge construction are complete, and the procedures are complete. The specifications and standards cited in the anti-capillary reinforcement design are correct; the construction unit organizes construction according to the design plan. - ) After professional institutions, the concrete rebound method test results of bridge pier columns and cover beams meet the design specification requirements; the spacing of the main ribs of the pier column meets the design documents requirements; the structural dimensions of the pier column meet the design documents requirements; the weld quality of the random sampling of the steel box girders on the upper bridge meets the design documents requirements; the cross-sectional size and steel plate thickness of the steel box girders randomly inspected meet the design documents requirements.
- ) The professional unit reviewed and concluded that the calculation method in the calculation report provided by the design unit is appropriate; the anti-capillary stability coefficient of the bridge after empirical calculation is ≥2.5. ) The results of regular inspection of bridges believe that the overall technical condition of the bridge is good.
- is allowed to pass after review, and the "Overlimited transport vehicle pass" is issued, and a series of supporting safety measures and requirements are required to be implemented. For example: it must pass at a specified time, route and speed, and must drive in a center on the bridge, etc. Although
- is allowed to pass after review, on the basis of the previous article, escort measures along the road need to be taken, including escort plans, operating rules, and handling of unexpected situations. If necessary, the route administration and traffic police along the route need to implement corresponding traffic control measures. Although pass through line survey and structural verification of bridges along the line is allowed, in addition to the above safety measures, certain transformation and reinforcement measures must be implemented for some bridges, structures, etc. along the line. Because some roads, bridges, and structures may not meet the conditions for overloading vehicles. It should be pointed out here that the transformation and reinforcement measures and the cost entities are implemented and borne by the "carrier".
- is not allowed to pass after line survey, structure verification and comprehensive evaluation.
8. What is the nature of the accident-related vehicle group transportation?
In my country's heavy-duty truck production, manufacturing standards and transportation management, the total mass of trucks and cargo of large freight vehicles (such as six-axle articulated trains) is 49 tons, and the total length of the vehicle does not exceed 20m. Correspondingly, the vehicle load used in my country's expressway bridge design is 55 tons, and the vehicle shaft load used in the engineering design is 10-14 tons/axle (14 tons of bridge and 10 tons of road surface).
. In this accident, the vehicle group involved in the accident was a behemoth composed of 3 tractors and two trailers ( has a total mass of 521.96 tons, a maximum axle load of 32.1 tons, and a total length of 67.67 meters. The vehicle group involved in the accident is several times larger than that of ordinary large trucks and vehicles in terms of total mass and body length, and far exceeds the requirements of road design (bridges, road surfaces, turning radius, etc.) for vehicle load, shaft load, profile dimensions, etc. belongs to a special overlimit transportation property .
9. What is over-limit transportation and what is the difference between it and ordinary freight?
Since the over-limit transportation conditions (total vehicle load, shaft load, vehicle profile dimensions, etc.) are not normal operating conditions for highway design and operation, that is, highway design will not consider this special need, therefore, over-limit transportation vehicles cannot pass on the road at will. The state has specially issued the "Highway Management Regulations for Over-limit Transport Vehicles to Driving " ( Ministry of Transport of the People's Republic of China Order, No. 62, 2016), requires that over-limit transportation must be reported to the relevant management departments along the road in advance, and only after approval can you obtain the "Over-limit Transport Vehicle Pass" and pass on the road.
According to the "Operational Regulations on the Management of Highways for Over-limit Transport Vehicles", over-limit transportation approval includes pre-inspection, verification and other processes, especially for special over-limit transportation needs, and the traffic conditions of all roads, bridges, tunnels, intersections, etc. along the route must be inspected and verified.
To summarize, according to the load, profile size of overlimited transport vehicles, and technical conditions of highway bridges along the route, the overlimited transport approval results are generally divided into the following situations:
In summary, highway design and construction must meet the legal requirements of ordinary freight transportation, but over-limit transportation is different. Over-limit transportation does not belong to the working conditions designed by highways (including bridges, etc.), and its traffic and management are completely different from ordinary freight. Management departments at all levels have the right to not allow them to pass through the road in accordance with the law.
