How is the protection level of the crash barrier divided?

The protection level of the crash barrier is mainly divided according to the collision energy it can withstand. The following is a specific introduction:
First, according to the standard division
In China, the protection level of crash guardrail is generally based on the Design Code for Highway Traffic Safety Facilities (JTG D81) and other relevant standards. Protection grade from low to high divided into B, A, SB, SA, SS five levels.
Level B
It is suitable for general roads and rural roads with small traffic volume and relatively low vehicle speed. The collision energy it can withstand is relatively low, and it can generally protect small buses from collisions at a speed of about 70km/h. In this case, the crash barrier mainly plays a basic role in guiding the vehicle and blocking the vehicle to a certain extent, reducing the possibility of the vehicle deviating from the road.
Level A
It can be used in secondary highways and some urban expressways. It can resist the collision of medium-sized buses at a speed of about 100km/h. Its structural strength and height parameters are more protective than Class B, can better prevent the vehicle from running off the road, and can guide the vehicle to return to the normal direction of travel after a vehicle collision.
SB and SA
It is often used in the central divider of expressways and some key sections. The SB class can withstand a large bus collision at a speed of about 80km/h, and the SA class can withstand a large bus collision at a speed of about 100km/h. These two levels of crash guardrail should not only have a strong blocking ability, but also have good energy absorption characteristics to reduce the impact of the vehicle collision on the occupants of the car.
 Level SS 
It is the highest level of protection, mainly used in some special high-risk sections, such as large Bridges on expressways, tunnel entrances and exits, and other key locations. It can withstand heavy vehicle collisions at speeds of around 100km/h, its construction is more robust, and the materials and design are designed to maximize traffic safety in extreme situations.
 Divide considerations
The classification of protection levels also takes into account various factors such as the importance of the road, traffic flow, vehicle type and speed. For example, on busy highways, due to the high speed of vehicles and the large number of vehicles, a higher level of crash guardrail is needed to ensure safety. In the internal roads of some scenic spots, the vehicle speed is slow, the traffic volume is small, and the lower level of collision guardrail can meet the basic safety needs.