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. Generally, bridge fire protection can be divided into four levels: A, B, C and D.

Level A is the highest level of bridge fire protection. It requires the use of fire-resistant materials and fire-resistant coatings on the bridge structure, as well as the installation of fire-resistant doors and windows. In addition, the bridge should be equipped with fire-fighting equipment and fire-fighting systems.

Level B is the second highest level of bridge fire protection. It requires the use of fire-resistant materials and fire-resistant coatings on the bridge structure, as well as the installation of fire-resistant doors and windows. In addition, the bridge should be equipped with fire-fighting equipment and fire-fighting systems.

Level C is the third highest level of bridge fire protection. It requires the use of fire-resistant materials and fire-resistant coatings on the bridge structure, as well as the installation of fire-resistant doors and windows. In addition, the bridge should be equipped with fire-fighting equipment and fire-fighting systems.

Level D is the lowest level of bridge fire protection. It requires the use of fire-resistant materials and fire-resistant coatings on the bridge structure, as well as the installation of fire-resistant doors and windows. In addition, the bridge should be equipped with fire-fighting equipment and fire-fighting systems.

In conclusion, 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. The four levels of bridge fire protection are A, B, C and D, with A being the highest level and D being the lowest.