Foundation Design for High Tension Cable Guardrails






Foundation Design for High Tension Cable Guardrails

Submitted by

Ling Zhu, Ph.D.

Former Graduate Research Assistant



John R. Rohde, Ph.D., P.E. Associate Professor

Ryan J. Terpsma, B.S.M.E. Graduate Research Assistant

Midwest Roadside Safety Facility University of Nebraska-Lincoln

130 Whittier Building Lincoln, Nebraska 68588-0853

(402) 472-0965

Submitted to


Mid-America Transportation Center 262 Whittier Building

Lincoln, Nebraska 68588-0853

MwRSF Research Report No. TRP-03-236-10

June 2010



High tension cable guardrail is becoming increasingly popular in median and roadside

applications due to the promise of reduced deflections upon impact and reduced maintenance.

These systems show better performance in redirecting vehicles and preventing median

crossovers than traditional low-tension cable guardrail systems. These high tension systems have

also been shown to be more easily repairable with the undamaged lengths functioning properly

throughout the repair process. As the performance of these systems is observed in service, there

is a growing concern over the end anchorage foundation performance of current systems.

Foundations for high tension systems must not only be capable of restraining the impact load of a

vehicle, but must also restrain the initial pretension on the cable system as well as temperature

induced loads. While it may be acceptable for many roadside safety devices to require

foundation repair after impact, foundation failure due to environmentally induced loads would be

a serious maintenance problem. As temperature induced loads can be greater than those loads

applied during impact, these loadings must be considered in foundation design. Foundation

deflection can reduce cable tension, increasing deflection of the system during impact and letting

the cables sag after impact. The soil conditions in which these foundations are placed vary

significantly. A soil specific foundation design would assure the functionality of these high

tension systems.


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