Which railing uses W-shaped steel beams as the primary structural element and is commonly used on highways to contain and redirect vehicles?

• A. Thrie beam railings
• B. W-beam bridge railings
• C. Tubular rail system
• D. Cable railings

Answer: (B)

W-beam guardrails are designed specifically for highway safety because their W-shaped steel rails act as the primary structural element that contains and redirects vehicles after impact. The cross-section provides a predictable bending path; when a vehicle strikes the rail, the rail deforms and slides along the posts, dissipating energy and guiding the vehicle back toward the roadway rather than penetrating the barrier. This energy absorption and redirection behavior is engineered into the W-beam system, with posts and end treatments working together to maintain a controlled, replaceable barrier after a collision.

Thrie beam railings use three rails, which improves strength but does not define the W-shaped cross-section described in the question. Tubular rail systems rely on round tubes, offering a different aesthetic and performance. Cable railings use tensioned cables and are not designed to contain vehicle impacts.