Crash Testing
MASH Test 3-35
Post 2 impact (PASS)
6’-3” from Post 1
12’ from Post 0 (Anchor Post)
Simulation
MASH Test 3-35
Post 1 impact (PASS)
0’ from Post 1
6’-3” from Post 0 (Anchor Post)
Beginning of Length of Need
Concave Curves (Inside of Curve)
When installed on concave curves, any end treatment will encroach upon the shoulder if it is installed within the curve.
C: DO NOT TERMINATE HERE. Terminating on a tangent from Point C will encroach upon the shoulder. NGT guardrail should never be bent or curved in the horizontal plane, including at any of the splices located within the proprietary length of the NGT.
D: install the NGT with an offset between 0 and 1.5 feet.
Convex Curves (Outside of Curve)
Consider the guardrail to be comprised of two systems: (1) the curved guardrail, and (2) the NGT. At the point where the curved guardrail ends, the NGT should be installed tangent to it, tapering away from the road. At no point should any rail element of the NGT be curved to match the curvature of the road or the downstream guardrail. There should be no need to offset the NGT away from the tangent line.
A: install the NGT along the tangent line to the end of the curved installation. This will produce an automatic offset that will aid with maintenance without encroaching on the shoulder.
The curved distance between A and B should not exceed , where is the radius of the curvature of the road in feet.
See this Design Spreadsheet for terminal position as a funciton of roadway curvature
B: install the NGT with an offset between 0 and 1.5 feet.