Components, systems and materials › Road furniture and safety › W-beam crash barrier
W-beam crash barrier
What it is
A W-beam barrier is a steel guardrail with a W-shaped corrugated profile, bolted to posts along the road edge or median to redirect errant vehicles.
Where it is used
Highway edges at embankments, culverts, steep slopes and roadside hazards, and in medians.
How it works
It is a semi-rigid system. When a vehicle strikes at an angle, the rail acts as a tension band, posts bend or rotate in the soil, and the rail deflects, turning the vehicle back along the road while spreading the deceleration over time. Spacers (blockouts) hold the rail away from the posts so wheels do not snag on them.
Types
- Single-sided roadside
- double-sided median
- with or without spacers
- various containment levels by tested system
Materials
Galvanised steel W-beam rail, steel posts, spacers, splice bolts, crash-tested end terminals.
Barriers are chosen by containment level and working width from crash-tested systems, and placed only where hitting the barrier is less harmful than the hazard. The length of need ahead of the hazard, the height of the rail, the post embedment and the treatment of ends all matter. IRC:119, EN 1317 and AASHTO MASH set out testing and guidance.
Installation and QA steps
- Set out line and level
- Drive or set posts to the specified embedment and spacing
- Fix spacers and rail with laps in the direction of traffic
- Torque splice bolts
- Install crash-tested end terminals or flare and anchor the end
- Check rail height
- Blunt or buried ends that spear or launch vehicles
- Rail too low after overlays
- Posts in weak ground
- Gaps at bridge transitions
Codes cited
- IRC:119 (India): Guidelines for traffic safety barriers.
- EN 1317 (series) (Europe): Road restraint systems: performance classes and impact test methods.
- AASHTO MASH (USA): Manual for Assessing Safety Hardware: crash test procedures for roadside hardware.
Cited by number only. We do not reproduce code text, tables or figures.
Related
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