Traffic Barrier
ELM-TRB-23 Situational / Discouraged Element
Traffic Barrier
A longitudinal barrier (guardrail, concrete barrier, or similar rigid or semi-rigid structure) installed to redirect an errant vehicle away from a roadside hazard or opposing traffic, rather than allowing the vehicle to travel further off-course.
Related Media
#Why this pattern exists
Certain roadside conditions (a steep slope, a fixed object, an opposing travel lane with no separation) pose a severe risk if an errant vehicle reaches them; a traffic barrier is deployed specifically to intercept and redirect the vehicle before it does, at the cost of introducing its own fixed-object risk if struck directly. This pattern exists to document when that tradeoff is justified.
#Key considerations
- Should only be installed where the hazard being shielded is more severe than the barrier itself, since the barrier becomes a fixed object a vehicle can strike1
- End treatments matter significantly; an unshielded or improperly terminated barrier end can be more dangerous than no barrier at all
- Height and strength must be matched to the design vehicle and speed of the roadway it protects, crash-tested against current standards2
#Related patterns
Crash Cushion/End Terminal (ELM-CCT-24) (the treatment addressing this pattern’s exposed ends); Bollard (ELM-BOL-25) (a related but functionally distinct barrier type)
#References
- Legal / regulatory American Association of State Highway and Transportation Officials, Roadside Design Guide, 4th ed.(opens in new tab)
- Legal / regulatory American Association of State Highway and Transportation Officials, Manual for Assessing Safety Hardware (MASH), 2016.(opens in new tab)
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