Brakes fail, concrete truck goes downhill: The moment of the accident

To analyze the accident of this concrete mixer truck on a mountain road, we need to consider multiple factors, including the structure and load of the vehicle, road conditions, climate factors, driving operation, and braking system.

1. Vehicle structure and load

Characteristics of concrete mixer trucks: Concrete mixer trucks usually have a high dead weight because their body structure needs to carry a heavy mixing barrel, and a large amount of concrete needs to be loaded in the barrel. Concrete has a high density, and the weight of each cubic meter of concrete can reach about 2,300 kilograms. If the vehicle body does not have a reasonable load balance, especially when driving on a slope, the center of gravity of the vehicle body is high or too concentrated, which can easily lead to control difficulties.

Poor climbing performance: When a concrete mixer truck is driving on a steep slope, if the vehicle body is too heavy, especially when the slope is large, the traction of the vehicle may not be enough to overcome the downward pull of gravity. Therefore, although the engine power may be sufficient to support normal driving, when the load is too heavy or the slope is too large, the speed will gradually decrease, and eventually it will be unable to continue climbing, and may even start to slide.

2. Road conditions and geographical environment

Slope and turns: Mountain roads often have large slopes and sharp turns, which are a challenge for any vehicle. Especially on heavier and longer vehicles such as concrete mixer trucks, the vehicle's roll and braking distance will increase when turning. When the slope is steep and the turn is sharp, the stability of the vehicle is seriously threatened, especially when the speed cannot be reduced, the vehicle is easy to lose control.

3. Driving operation

Driver reaction time and control ability: After the concrete mixer truck fails to climb the slope, it may start to slide down due to the gravity of the vehicle. If the driver does not judge this situation in time or fails to make the correct operation (such as slowing down or shifting gears), the vehicle will further accelerate and roll down the slope. The curves and slope changes on mountain roads may limit the driver's field of vision, making it difficult to detect danger and respond in time.

Emergency braking operation: When the concrete mixer truck starts to go downhill, the driver usually tries to slow down by emergency braking. However, if the brake system is not well maintained or the braking efficiency is reduced due to climate change, the probability of brake failure will increase. Especially on slippery roads, the brakes may not be able to effectively generate enough friction, resulting in the vehicle being unable to stop in time.

4. Failure of the brake system

How the brake system works: Modern car brake systems usually rely on hydraulic or pneumatic systems to control the brakes, but if there are problems such as leaks, insufficient air pressure or lack of hydraulic oil in the brake system, the braking effect will be greatly reduced. Especially on continuous uphill and downhill roads in mountainous areas, the brake system is under a heavy burden, and frequent braking operations may cause the brake system to overheat, further affecting the braking effect.

The effect of air gradient: This may refer to abnormal operation of the brake system due to changes in air pressure on mountain roads. In some special cases, the mountainous environment with low air pressure may cause the brake system to perform unstable, especially in the case of high air humidity or drastic temperature changes, the effectiveness of the brake system may be reduced.

Over-reliance on brakes: If the driver relies too much on the brakes during the downhill process and does not use the appropriate gear (such as low gear), this will cause the brake system to work for a long time, resulting in overheating and possible brake failure.

5. Occurrence and consequences of the accident

Vehicle rollover and falling into the ditch: Due to brake failure, the vehicle cannot stop in time, which may cause the vehicle to lose control of the driving trajectory during the downhill process, and eventually lose control and roll over. Mountain roads are mostly narrow and curved. If there is no guardrail on one side or the side slope is deep, the vehicle may roll down the hillside or fall into the ditch.

The root cause of this accident is the superposition of multiple factors:

The vehicle is overweight, resulting in insufficient power to support climbing;

The road conditions are poor, and the combination of slope and curves increases the risk of loss of control;

Brake failure may be due to climate change, brake system failure or over-reliance on brake operation;