1.What are the main types of guardrail posts used on highways?
Highway guardrail posts (commonly known as "guardrail posts") primarily use hot-dip galvanized steel pipes or sections, rather than thin-walled posts formed directly from galvanized coils through cold bending.
Although broadly speaking, their base material is galvanized steel, they differ significantly in manufacturing processes, thickness (wall thickness), strength, and applications.
2.What are the differences in the manufacturing processes between highway guardrail posts and posts made from galvanized coils?
Highway guardrail posts: First, forming: using thick steel plates (strips) rolled and welded into steel pipes, or directly hot-rolled into structural steel sections.
Then, galvanizing: the formed steel pipes/sections are hot-dip galvanized as a whole.
Columns made from galvanized steel coils:
First, galvanizing: Thin steel strips are galvanized to form galvanized coils.
Then, forming: The galvanized coils are rolled, bent, and welded into round or square tubes using a cold bending forming unit.
3.What are the differences in strength and safety between highway guardrail posts and posts made of galvanized coils?
Highway guardrail posts: extremely tall. As a primary load-bearing safety component, they are designed to block and cushion vehicle impacts in a traffic accident, absorbing energy and preventing vehicles from running off the road.
Posts made of galvanized coils: Relatively low. Thin walls and insufficient overall structural rigidity, unable to withstand impacts from high-speed vehicles. Primarily used in non-load-bearing or low-risk areas.
4.Why must highways use thick-walled hot-dip galvanized columns?
Safety First: The core function of a guardrail system is "collision protection." In the event of a traffic accident, the posts must have sufficient strength to support the guardrail panels and absorb collision energy through their own deformation, guiding vehicles back to their normal direction. Thin-walled posts will break instantly upon impact, posing an extreme danger.
Long-Term Corrosion Resistance: Replacing highway facilities is extremely costly and disrupts traffic. Therefore, posts are required to have an extremely long service life (typically over 30 years). Thick-walled substrates combined with a thick hot-dip galvanized layer provide the most reliable corrosion protection.
Mandatory National Standards: Chinese transportation industry standards (such as JT/T 281-2007 "Wave-beam Steel Guardrail" and GB/T 31439.1-2015 "Wave-beam Steel Guardrail") have mandatory requirements for the material, dimensions, wall thickness, and galvanization amount of guardrail posts. Thin-walled, cold-formed galvanized coil posts cannot meet these standards.
5.What are the differences in the galvanized layer between highway guardrail posts and posts made from galvanized coils?
Highway guardrail posts are hot-dip galvanized as a whole, with a thick zinc layer (usually ≥600g/m²), and a uniform zinc layer on both the inside and outside, providing extremely strong corrosion resistance and a lifespan of several decades.
The columns are made of galvanized coils. The galvanization is completed at the coil stage. During the cold bending and welding process, the zinc layer at the weld may be damaged, becoming a potential starting point for corrosion.