H4b-B-W4 bridge Guardrail system

Guardrails, also known as road safety barriers or vehicle restraint systems, are longitudinal roadside safety installations designed to reduce the severity of run-off-road and median-crossing accidents. Their primary function is to contain and redirect errant vehicles while minimizing injury to vehicle occupants and other road users.

Guardrails are typically installed along highways, rural roads, bridges, medians, embankments, and hazardous roadside areas such as curves, slopes, water bodies, or fixed obstacles (e.g., poles, trees, abutments).

Function and Performance

The main functions of guardrails include:

• Vehicle containment: Prevent vehicles from leaving the roadway or crossing into opposing traffic.

• Redirection: Safely guide vehicles back toward the roadway.

• Energy absorption: Dissipate kinetic energy during impact through controlled deformation.

• Risk reduction: Minimize impact severity compared to collisions with rigid obstacles.

Performance is typically verified through full-scale crash testing in accordance with standards such as:

• EN 1317 (Europe)

• MASH (Manual for Assessing Safety Hardware, USA)

• NCHRP Report 350 (legacy U.S. standard)