TTI Research Supervisor:
Nauman Sheikh
Texas A&M Transportation Institute [email protected]
Pooled Fund Technical Representative:
Erik Emerson
Roadside Safety Engineer
Wisconsin Department of Transportation
Bureau of Project Development
(608)266-2842 [email protected]
ABSTRACT
W-beam guardrail is often installed near a retaining wall or rip rap. Installing the guardrail too close to a retaining wall or rip rap constrict the lateral movement of the guardrail posts that can degrade the ability of the guardrails to contain and redirect an impact vehicle. Installation of the guardrail too close to a retaining wall can also result in additional loading on the wall due to the vehicle impact. The additional loading should be accounted for in the retaining wall design. Similarly, if the guardrail is installed too close to rip rap, an impacting vehicle can disturb the rip rap, resulting in costly repairs.
The research provides additional loading on the retaining wall due to a vehicle impact on a guardrail that is installed adjected to the retaining wall. Loafing is provided for different lateral offsets of the W-beam guardrail from the retaining wall. This research also provides an optimal lateral offset between the W-beam guardrail and rip rap. This offset is expected to result in minimal disturbance of the rip rap due to a vehicle impact on the guardrail and allow the vehicle to redirect smoothly without riding over the rip rap.
Finding of this research provide retaining wall design engineers with additional loading information to design safer retaining walls that can withstand the guardrail impact loading. It also provides minimum lateral offset guidance for guardrail installations adjacent to retaining walls to rip rap.
