The main objective of the proposed research is to evaluate the performance of the 29-in and 31-in NCDOT guardrails under MASH Test Level 3 (TL-3) conditions when placed on six-lane, 46-foot median divided freeways. The double-faced W-beam guardrail, which was proposed to replace two lines of single-faced 27-in guardrails on such freeways, will also be evaluated at new rail heights of 29 and 31 inches. Finite element modeling and simulation will be employed to evaluate all the guardrails under impacts of both a small passenger car and a large pickup truck. A comparison will be made with the performance of a G4(1S) 27-in W-beam guardrail placed on six-lane, 46-foot median divided freeways. The effects of horizontal curvature on guardrail performance will also be evaluated using the 29-in and 31-in single- and double-faced guardrails.
NCDOT officials will be able to use the research results to update the Roadway Standard Drawing for guardrail installation on six-lane, 46-foot median divided freeways. For roadway improvement projects, NCDOT engineers will be able to make better decisions on guardrail types (i.e., single- or double-faced), rail heights and placement.
