Nine questions about the Lixinsha Bridge accident!
The Guangzhou Maritime Safety Bureau reported that at about 5:30 on the 22nd, a container ship was empty on the way from Nanhai, Foshan, Guangdong Province to Nansha, Guangzhou, and touched the pier of the Lixinsha Bridge when it sailed through the Hongqi Lishui Road, causing the bridge deck of the Lixinsha Bridge to break and a vehicle to fall into the water.
The owner of the vessel involved has been taken into custody.
According to the latest report of the Guangzhou Maritime Search and Rescue Center: as of 10:00 a.m. on February 22, after a preliminary investigation, 4 vehicles involved in the accident and 1 electric motorcycle, of which 2 vehicles fell into the water and the other 3 fell to the boat.
So far, 2 people have been rescued, 2 people have died, 1 crew member has been slightly injured, and 3 people are missing. The cause of the accident is being investigated, and rescue work is being carried out in an orderly manner.
As an ordinary person, it is very sad to see the news that there are people! In line with the principle of prevention before it happens and asking questions if you don't understand, I want to ask a few simple and basic questions, and I hope the authorities will answer
1. Is the Lixinsha Bridge navigable? Or during the navigation period? (After all, there are periods of high water and periods of dry water).
This is a very basic question, but it is very critical to this incident, and it stands to reason that there should be a corresponding introduction on the Internet, but I have not retrieved any relevant information on the Internet, so I hope for an official reply.
2. If it is not navigable at present, is this ship the first ship to sail from here? Is there anyone in charge of supervising the no-sail areas or no-sail periods? Why didn't anyone stop it?
If it is clear that navigation is not allowed, knowing the law and breaking the law, this incident is undoubtedly the main responsibility of the owner of the ship involved, but the relevant maritime authorities also have the responsibility of poor supervision, the news shows that the ship involved is empty, indicating that it is a return trip, so why did not stop navigation when it came?
3. If it can be navigated, is there any regulation for navigation? Are there any restrictions on vessel sizes?
The author learned from the relevant literature that there are safety standards for ship navigation:
When a large ship crosses the bridge, the height above the waterline of the ship should be met: the maximum height above the waterline of the ship (the maximum height above the keel - the draft of the ship) (the clearance height of the bridge - the safety margin) + (the maximum design navigable water level - the tide height when passing).
Determination of safety margins.
The safety margin is the surplus left to ensure the safe operation of the ship under the bridge, and the selection of the safety margin should fully consider all factors
1) The pitch and heave of the ship will change the maximum height of the ship above the waterline.
2) The altitude changes that occur after the overhaul of the ship, the error of the ship's altitude measurement, and the change of the ship's draft difference in saltaminous and seawater should also be taken into account.
3) Errors in water level observation, forecasting, and meteorological water enhancement forecasts. For example, the Chinese version of the "tide table" forecasts the tide height error range of 20-30cm.
4) The recommended value method of the safety margin is 2m in the inland waters of navigable ships and sea areas with small wind and waves; In the open sea area with large waves, it is advisable to take 4 m through bridges built on important waterways.
This standard is introduced in detail, if it is strictly implemented in accordance with the standard, there will be no safety accidents, then the question is, for the implementation of this standard is consciously dependent on the shipowner or there are relevant departments to check? Is there any regulation? What are the regulatory standards?
4. About the quality of the bridge!
The author is a civil engineering major, and I would like to say a word for the design and construction of this bridge
The impact load generated by the collision of ships is much higher than the static load that the bridge needs to bear in the usual transportation, if our design code requires that the impact load of the ship must be taken into account when designing the bridge, then the budget of the bridge construction in the country will be increased a lot, which is not suitable for the current situation in our country, so our national code will not force the impact load must be considered, so in real life, if the bridge is impacted, the structural problem is reasonable.
Some people also mentioned that the bridge is a prefabricated building, and the conclusion is that the prefabricated building is not safe, which is also not rigorous, although the vandalism resistance of the prefabricated building is indeed not as good as the overall pouring, but the bearing capacity is also absolutely in line with the national design standards.
Therefore, it is not rigorous to deduce from "impact caused bridge damage" and "there are problems in bridge design and construction".