Bridge fire protection is an important part of bridge engineering. It is necessary to classify bridge fire protection into different levels in order to ensure the safety of bridges and the people who use them.

Generally speaking, bridge fire protection can be divided into four levels: A, B, C, and D. Level A is the highest level of fire protection and is usually used for bridges that are located in areas with high fire risk. This level requires the use of fire-resistant materials, such as steel, concrete, and other materials that can withstand high temperatures.

Level B is the second highest level of fire protection and is usually used for bridges located in areas with moderate fire risk. This level requires the use of fire-resistant materials, such as steel, concrete, and other materials that can withstand moderate temperatures.

Level C is the third highest level of fire protection and is usually used for bridges located in areas with low fire risk. This level requires the use of fire-resistant materials, such as steel, concrete, and other materials that can withstand low temperatures.

Level D is the lowest level of fire protection and is usually used for bridges located in areas with very low fire risk. This level requires the use of fire-resistant materials, such as steel, concrete, and other materials that can withstand very low temperatures.

In conclusion, bridge fire protection is an important part of bridge engineering and it is necessary to classify bridge fire protection into different levels in order to ensure the safety of bridges and the people who use them. By doing so, bridges can be better protected from the dangers of fire and other disasters.