The installation of guardrail pillars, wave beams, anti-blocking blocks, and brackets should meet design and construction requirements.
To ensure the overall strength of the guardrail, the compactness of the road shoulder and central divider soil foundation should not be less than the design value. Guardrail pillar installation should not be carried out on sections that do not meet compaction requirements. The buried depth and foundation treatment of the w beam highway guardrail pillars on rocky road sections and retaining walls should meet the design requirements.
The end treatment of the wave beam guardrail and the transition section with the bridge guardrail should meet the design requirements.
Adhesion of Zinc Layer
The adhesion test of galvanized layer adopts hammering method. The test piece is placed horizontally, the hammer head is facing the center of the bracket, the hammer handle is perpendicular to the base plane and is dropped freely, and five points are hammered in parallel with 4mm interval. The adhesion of the zinc layer is judged by inspecting the surface state of the zinc layer, whether there is peeling and bulging phenomenon. The impact points should be 10mm away from the end of the specimen, and the same point shall not be impacted twice.
Performance test of w beam highway guardrail material
The mechanical properties of steel mainly refer to the strength properties, which can be divided into strength properties, plasticity and impact toughness. Strength properties represent the resistance of steel plastic deformation and damage, including elastic limit, yield limit, strength limit, fatigue limit and hardness.
Plasticity represents the plastic deformation capacity of steel, including elongation, area reduction rate and cold bending. Impact toughness represents the resistance of steel to impact load.
Because the content of various components in the highway guardrail material affects the mechanical properties of steel, the performance test.
Adhesion test of Zinc plating layer
Zinc used for hot dip galvanizing shall be 0 or 1 zinc specified in GB470, and the zinc adhesion and plating layer thickness shall meet the requirements of zinc adhesion test. The test can be conducted bythiocyanate method or coating thickness gauge.
Eliminate obstacles in the clear zone on the side of the road;
Plan obstacles from the source so that vehicles can pass safely;
Move obstacles to a position that is not easy to be impacted by the highway guardrail;
Adopt deceleration and energy dissipation devices to reduce the severity of vehicle impact on obstacles.
When the above methods cannot be implemented, the guardrail should be set when the severity of the incident caused by the out-of-control vehicle exceeds the severity of the guardrail bumping.
Whether the guardrail should be set should be judged according to the danger level of the roadside, the probability of the incident, the working speed and the main factors of traffic composition.
Generally speaking, the sections of highway guardrail should be those sections where personnel casualties, property losses are serious after accidents, and those sections with high frequencies of accidents. The following factors should be considered when setting up:
It is necessary to protect the safety of drivers and passengers from damage caused by vehicles driving off the road (including roadside), such as cliffs, retaining walls, viaducts, and sections along rivers, lakes and seas;
It is necessary to protect the safety of vehicles from secondary damage caused by driving off the road, such as sections along railways and other important routes, and central separation strips in expressways;
Sections with frequent accidents, bad weather conditions or other sections where highway guardrail is necessary.
It should be noted that improper or excessive setting of guardrails will also add to the accidents.