What is a Guardrail? | Complete Guide to Choosing, Purchasing ...

Introduction: The Thin Line Between Rescue and Disaster

On the roads, the boundary between surviving a deadly accident or plunging off a cliff comes down to just one thing: the guardrail. This simple metal barrier, installed along the edges of busy routes, carries a heavy responsibility — saving human lives. The guardrail, or roadside fence, may appear silent and still, yet in practice, it is one of the most essential road safety devices.

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Applications of Guardrails in Road and Urban Projects

1. Safety on Highways and Expressways
   At high speeds, a vehicle leaving the roadway can be fatal. Highway guardrails prevent vehicles from veering into oncoming traffic or running off the road.

2. Along Cliffs, Rivers, or Valleys
   In areas with a risk of falling, roadside metal barriers are vital for driver safety.

3. Separating Opposite Traffic Lanes
   Using median guardrails helps reduce head-on collisions.

4. Urban Projects and Parking Areas
   In urban environments or large parking lots, roadside barriers are also used to control traffic flow and protect pedestrians.

Types of Guardrails and Their Technical Specifications

Guardrail TypeTechnical SpecificationsMain ApplicationSimple W-Beam GuardrailMade of hot-dip galvanized steel sheet, 2–3 mm thick, 31 cm wideHighways, expresswaysThree-Wave GuardrailStronger and heavier, with high durabilityHigh-traffic or hazardous routesDouble GuardrailDouble-layer barrier with extra strengthBridges, mountainous areas with steep slopesFlexible GuardrailRestores shape after impact, suitable for accident-prone areasBusy and high-risk locationsDecorative Urban GuardrailAttractive design with powder coatingStreets, landscaping, parking lots

Advantages of Standard Road Guardrails

✅ Increased road safety
✅ Reduced fatalities and property damage in accidents
✅ Prevents vehicles from falling off cliffs
✅ Separates lanes and organizes traffic flow
✅ Resistant to corrosion, moisture, and sunlight
✅ Easy to install and maintain

Guardrail Buying Guide – Key Points to Consider

1. Galvanized sheet thickness: Direct impact on strength and price
2. Type of joints, bolts, and nuts: Stainless steel or galvanized steel
3. Surface coating: Hot-dip galvanizing or powder coating?
4. Ground type at installation site: Soil, concrete, or asphalt?
5. Required impact resistance: Based on the accident rate of the area
6. Environmental moisture or corrosion level: Choose anti-rust models for humid or industrial zones
7. Application type: Road, bridge, tunnel, urban area, or industrial site?

Guardrail Price – Factors Affecting the Cost

Price FactorDescriptionSheet thicknessUsually between 2–3 mm; the thicker, the more expensiveMetal coatingHot-dip galvanizing costs more but offers higher durabilityType of guardrailSimple, three-wave, double, or flexible?Number of impact absorbersMay require additional equipment such as posts and impact attenuatorsBrand & manufacturerQuality and service warranty affect the price

Guardrail Installation – Steps and Execution Tips

1. Prepare the installation site

2. Install steel posts at standard intervals

3. Assemble and connect the guardrail sheet to posts using bolts and nuts

4. Install impact attenuators (if required)

5. Perform final stability and safety tests

Global Guardrail Standards

• EN : Impact resistance requirements

• AASHTO M180: Road guardrail specifications

• ISO : Hot-dip galvanizing to prevent rust

• ASTM A123: Zinc coating standard

• Iran National : Adaptation to Iran’s climate conditions

Mahyar Sepahan Guardrail Projects