INSIDE THE DOT
South Dakota Department of Transportation
Crash Testing of W-Beam to Cable Transition
Dean Sicking, U of Nebraska
South Dakota Department of Transportation uses a guardrail system composed of W-beam near the object to be protected and three-cable guardrail further away. The transition from W-beam to the three-cable guardrail had not been tested according to the National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. The Midwest Roadside Safety Facility conducted crash testing of South Dakotas guardrail design. The first phase of work involved analysis of the current design to determine the critical impact point. A computer analysis of the existing guardrail system determined the three-cable guardrail post spacing at the W-beam terminal needed to be reduced from the current 8 post spacing to a 4 post spacing. Crash testing according to NCHRP Report No. 350 was conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. Three full-scale crash tests were successfully performed. The South Dakota cable guardrail to W-beam transition successfully met current safety standards and is recommended for use along the National Highway System.
1 To evaluate the safety performance of the South Dakota Department of Transportation’s cable guardrail to W-beam transition according to the Test Level 3 (TL-3) evaluation criteria provided in NCHRP Report No. 350.
1 Review existing guardrail system design to determine the critical impact point and identify any weaknesses that may exist in the system.
2 Perform full-scale crash tests according to the Test Level 3 requirements specified in NCHRP Report 350.
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