Guardrails and End Terminals: Enhancing Roadside Safety

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Guardrails and End Terminals: Enhancing Roadside Safety

by Mitchell Chermak
QForensics

Introduction
Guardrails play a crucial role in ensuring roadside safety by preventing vehicles from encountering roadside hazards such as rigid objects, steep slopes, cliffs, or bodies of water. These protective barriers are strategically placed along highways, bridges, and curves to minimize the severity of collisions. In this article, we’ll delve into the world of guardrails, with a specific focus on guardrail terminals—the critical components that mark the beginning or end of a guardrail system.

Guardrail Face: Redirecting Vehicles Safely

The guardrail face is the visible part of the barrier that faces the road. Its primary purpose is to redirect a vehicle back onto the roadway if it veers off course. Here are some key points about guardrail faces:

1. Composition: The most common guardrail design features galvanized steel w-beam panels that are lapped and connected with rigid splice bolts. Alternative designs include concrete barriers and cable barriers.

2. Considerations: There is no single “best” barrier system. Each has its own benefits and potential drawbacks that make it better suited to specific applications.

o Cable Barrier: The high-tension cable barrier is often the preferred choice in relatively wide medians or on roadsides with sufficient “safe space” beyond the barrier. Cable barriers have the greatest dynamic deflection of the three prominent barrier types and are thus more forgiving for the occupants of the impacting vehicle. While this behavior is desirable in locations that allow for it, many sites where barriers are installed feature hazards located just beyond the barrier.

o W-Beam Guardrail: W-beam guardrail is considered to be a semi-rigid barrier. It allows for some dynamic deflection, thus reducing the impact forces exerted on occupants.

o Concrete Barrier: Concrete barriers are rigid and provide essentially no dynamic deflection (except for certain precast, temporary barriers, which can move somewhat when struck). This characteristic makes concrete barriers the least forgiving for the occupants of an impacting vehicle but sometimes the only option where no room for dynamic deflection exists because the hazard is immediately adjacent to the barrier.

End Terminals: Absorbing Kinetic Energy

While guardrails are intended to protect drivers from roadside hazards, they can also become a threat, particularly at the ends where the guardrail is secured with a rigid anchor. The narrow and relatively sharp end of the guardrail poses a risk to impacting vehicles. Guardrail terminals serve as essential components at both ends of a guardrail system, especially those within the clear zone for approaching traffic. Their purpose is to anchor the guardrail for redirective impacts while minimizing the severity of a direct hit. Here’s a closer look at end terminals:

1. Energy-Absorbing Guardrail Terminals:

o These designs dissipate energy through various means, gradually decelerating an impacting vehicle. This is most often achieved by extruding the guardrail through an impact head that kinks, cuts, or crushes the guardrail as it passes through.

2. Gating End Terminals:

o Gating end terminals are designed to yield, allowing a vehicle to pass if struck near the end. They function as a redirective barrier after a certain distance from the end.

Conclusion

Guardrails, with their end terminals, stand as crucial guardians of roadside safety. By redirecting vehicles and reducing crash severity, they play a pivotal role in saving lives and preventing severe accidents. As transportation infrastructure continues to evolve, it’s vital to appreciate these silent protectors while remaining vigilant about ensuring their optimal performance and safety standards.

For more information on guardrails and their significance in roadway safety, please visit Hot Dip Galvanized W-Beam Guardrail and Galvanized Highway W Beam Guardrail.