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Session 2

Session 2. Standard Guardrail Systems: Testing, Performance, and Characteristics. Session 2 Outcomes. Define the Tests Required for Guardrail Acceptance Explain How Guardrail Systems Function. Barrier System Elements. (AASHTO RDG). Functional Requirements of Guardrails. Contain Vehicle

vincent-moody
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Session 2

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  1. Session 2 Standard Guardrail Systems: Testing, Performance, and Characteristics

  2. Session 2 Outcomes • Define the Tests Required for Guardrail Acceptance • Explain How Guardrail Systems Function

  3. Barrier System Elements (AASHTO RDG)

  4. Functional Requirements of Guardrails • Contain Vehicle • No Penetration • No Vaulting • Redirect Vehicle • No Snagging 3. Tolerable Impact Forces

  5. NCHRP 350 Design Vehicles

  6. NCHRP 350 Barrier Tests

  7. V

  8. 3-Strand Generic Cable Guardrail

  9. Weak Post W-Beam Guardrail TL-2

  10. Weak Post W-Beam TL-3 2-11

  11. Box Beam Barrier

  12. Strong Post W-Beam Guardrail(Steel Blockout) 2-13

  13. Non-Collapsable Blockout 2-14

  14. Blockouts for Strong Post W-beam Steel posts: Non-collapsing blockout must be routed (or as tested) Wood posts: Wood blockout should be toe-nailed to post on each side* *Proprietary end treatments using wood blockouts and posts must have the blockouts toe-nailed to the post

  15. Guardrail Height

  16. Lapping of Guardrail “In the Direction of Traffic” - Upstream rail is in front of downstream rail

  17. Lapping of Guardrail - Detail

  18. Lapping of Guardrail TRAFFIC Improper Lap

  19. WASHERS on Standard Strong-Post W-beam NO WASHERS

  20. 3-Strand Generic Cable as Median Guardrail 2-21

  21. Example of Proprietary Cable System (HTC) 2-22

  22. Strong Post W-Beam Median Guardrail

  23. I I I I I I I I What happens when a vehicle hits a metal guardrail?

  24. Schematic I I I I I I I I

  25. Schematic I I I I I I I I

  26. I I I I I I I I What happened?

  27. Critical Feature for Guardrail Performance MUSTMaintain TENSION

  28. Session 2 Review What is the current criteria used to determine if barrier is acceptable for use on the National Highway? • Indianapolis 500 crashes • Anything existing on the highways today • NCHRP Report 230 • NCHRP Report 350

  29. Session 2 Review What modification was made to enable strong-post W-beam guardrails with steel posts to pass NCHRP 350 testing? • Bigger post size was used • Non-collapsible blockouts (wood) • Nested W-beam rail element added • Longer post length in the ground

  30. Session 2 Review What two features of metal guardrails are essential for optimum barrier performance? • Tension continuity and Color of rail element • Tension continuity and Minimum height • Minimum height and Direction of lap • Minimum height and Deflection distance for a fill slope

  31. SESSION 2 OUTCOMES • Define the Tests Required for Guardrail Acceptance • Explain How Guardrail Systems Function

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