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Phase I Development of a Non-Proprietary, Four-Cable, High Tension Median Barrier

REPORT NUMBER

TRP-03-213-11

AUTHORS

Mitch Wiebelhaus, Erin Johnson, Dean Sicking, Ronald Faller, Karla Lechtenberg, John Rohde, Bob Bielenberg, John Reid, Scott Rosenbaugh

PUBLICATION DATE

2011-12-28

ABSTRACT

During the last decade, the use of cable median barriers has risen dramatically. Cable barriers are often utilized in depressed medians with widths ranging from 30 to 50 ft (9.1 to 15.2 m) and with fill slopes as steep as 4H:1V. Although cable barriers have been shown to contain and redirect many heavy trucks, a careful review of accident records has indicated that passenger vehicles do occasionally penetrate through the standard 3-cable median barrier and enter opposing traffic lanes. As a result, the Midwest States Pooled Fund Program sponsored a research and development project to improve the safety performance of existing, non-proprietary, cable median barriers. These safety improvements included increased cable spacing, increased cable height, the use of four cables, increased cable tension, and optimized cable attachment to posts. Three Test Level 3 crash tests were performed on a four-cable, high-tension median barrier placed in a 46-ft (14.0-m) wide, 4H:1V V-ditch. All tests were conducted according to the safety performance guidelines provided in the Manual for Assessing Safety Hardware (MASH). The first test utilized a 2270P pickup truck impacting the barrier placed on a downslope and 12 ft (3.7 m) laterally away from the front slope break point. The vehicle was contained and redirected by the barrier and deemed acceptable according to the MASH guidelines. The second test utilized a 1100C small car impacting the barrier placed 27 ft (8.2 m) laterally away from the front slope breakpoint or 4 ft (1.2 m) up the back slope of the V-ditch. During the second test, the small car impacted the ditch bottom with a soft-soil condition and began to plow into the soil, thus causing moderate decelerations and velocity change before contacting the barrier and a marginal impact performance. The third test utilized a 1100C small car impacting the barrier in the same position as used in the second test. During the third test, the small car impacted the ditch bottom with a hard-soil condition and was contained by the barrier. However, excessive roof crush resulted when one of the cables slide up the vehicle and later snagged on the cable-to-post attachment hardware, thus resulting in a failed test. Design modifications are anticipated in a Phase II R&D effort.

KEYWORDS

Highway Safety, Roadside Appurtenances, Longitudinal Barrier, Cable Guardrail, High Tension, Crash Test, Compliance Test, MASH, Median Slope, V-Ditch, 4:1 Median Ditch

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