I. Functional Classification of Highway Safety Mesh

Isolation Nets and Crash Barriers

Isolation Safety Mesh: These safety nets are primarily used to demarcate boundaries and prevent intrusion. They are typically used to separate different traffic flows or isolate the highway from its surroundings. Examples include median strips and roadside fences. Median strips are usually equipped with anti-glare screens to block the glare from oncoming vehicle headlights and prevent vehicles from entering the opposite lane. Roadside fences are typically mesh structures that prevent pedestrians, livestock, and debris from entering the road, thus maintaining traffic order. These safety nets provide a moderate level of protection, focusing on isolation and warning functions.

Crash Barriers: These safety nets are designed to cushion impacts and reduce injury. They are typically installed on highway slopes, the outside of bridge railings, and at tunnel entrances—areas prone to vehicle veer-off or fall-off accidents. Based on impact resistance, safety nets can be classified as light, medium, and heavy. Heavy-duty safety nets typically use high-strength steel wire ropes or steel mesh. These safety nets absorb impact energy through deformation, effectively preventing vehicles from leaving the highway and minimizing personal injury and property damage. Some safety nets are also equipped with cushioning devices to enhance their protective performance.

II. Structural Forms of Safety Mesh

Mesh, Fence, and Combined Types

Mesh Safety Nets: This is the most widely used type of safety net on highways, using metal mesh as the primary protective material. Common materials include low-carbon steel, galvanized steel, and stainless steel. Mesh structures include welded mesh, woven mesh, expanded metal mesh, and wire rope mesh. Welded mesh is simple in structure and inexpensive, suitable for roadside isolation on ordinary highways. Wire rope mesh has high resilience and impact resistance, making it ideal for collision avoidance applications. Expanded metal mesh is strong and wear-resistant, suitable for highways with heavy traffic.

Fence-Type Safety Nets: These are constructed by welding or bolting posts, crossbars, and vertical bars to form a mesh structure. This type of safety net has moderate transparency and offers superior protective performance compared to standard mesh safety nets. Its regular shape simplifies installation and maintenance. Fence-type safety nets are commonly used at highway intersections and service areas, balancing protection and aesthetics. Some fence-type safety nets are also equipped with anti-climb spikes to improve safety.

Composite safety nets: These combine the advantages of mesh safety nets and fence-type safety nets, or integrate other protective components to form a composite structure, such as 'mesh safety net + fence' or 'mesh safety net + buffer posts.' These composite safety nets can precisely meet the protection needs of specific scenarios. For example, the 'wire rope net + anchor bolt + buffer ring' structure on highway slopes can resist rockfall impacts and adapt to terrain changes, providing comprehensive protection.

III. Material Characteristics of Highway Safety Mesh

Metal Mesh vs. Composite Mesh

Metal safety nets: Primarily made of metals such as steel and aluminum alloys, processed through welding, galvanizing, and powder coating. Low-carbon steel mesh is the mainstream choice due to its low cost and high strength, and is treated with hot-dip galvanizing and powder coating to enhance its corrosion resistance. Stainless steel mesh has extremely strong corrosion resistance and is suitable for harsh coastal or humid environments, but it is more expensive. Aluminum alloy mesh is lightweight, flexible, and easy to install, and is often used in areas with strict weight requirements, such as bridge facades.

Composite safety nets: These are made with a metal frame combined with polymer materials (such as PVC or fiberglass) or entirely from polymer materials. These safety nets combine the strength of metal with the corrosion resistance of polymers. For example, PVC-coated metal mesh retains the protective strength of metal while enhancing its resistance to acids, alkalis, and aging. Fiberglass mesh is lightweight and has good insulation, making it suitable for areas along highways with power facilities, but its strength is slightly lower than metal mesh.

IV. Applications and Advantages

Choosing the Right Safety Mesh

Choosing the right highway safety net depends on a variety of factors, including specific protection requirements, environmental conditions, and budget constraints. Separation nets are crucial for managing traffic flow and preventing unauthorized passage, while crash barriers minimize the impact of accidents in high-risk areas. The choice between mesh, fence, and composite structures depends on the requirements for visibility, aesthetics, and the required level of protection. Finally, the choice between metals and composite materials depends on factors such as corrosion resistance, weight, and cost. By carefully considering these factors, highway authorities can ensure that the selected safety net provides optimal protection and long-term durability.