Gardrails

Gardrails, also known as guardrails, are safety barriers used to prevent vehicles from leaving a roadway or a bridge and to reduce the severity of collisions. They are typically installed along the sides of highways, bridges, and other hazardous locations. The primary function of a gardrail is to redirect errant vehicles back onto the road or to absorb impact energy in a controlled manner.

There are several types of gardrails, with the most common being the W-beam guardrail. This consists of corrugated steel beams bolted together and supported by posts. When a vehicle strikes a W-beam, the corrugations help to flatten and absorb some of the impact energy, while the beams redirect the vehicle. Another type is the thrie-beam guardrail, which has a stronger, three-corrugated profile offering greater impact resistance. Cable barriers, made of tensioned steel cables supported by posts, are also widely used, particularly on medians, as they are flexible and can absorb significant impact energy.

The design and placement of gardrails are critical for their effectiveness. They are engineered to deform upon impact, dissipating energy and minimizing damage to the vehicle and its occupants. The height, strength, and anchorage of gardrails are carefully calculated based on expected vehicle speeds and impact scenarios. Regular inspection and maintenance are essential to ensure gardrails remain in good condition and can perform their safety function effectively.