Midwest Guardrail System Without Blockouts
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Transcript of Midwest Guardrail System Without Blockouts
Midwest Guardrail System Without Blockouts
J.D. Reid, R.K. Faller, R.W. Bielenberg, and K.A. LechtenbergMidwest Roadside Safety FacilityUniversity of Nebraska-Lincoln
TRB 2013January 14, 2013
Midwest Roadside Safety Facility
Acknowledgments• Midwest States Pooled Fund Roadside
Safety Program• MwRSF Staff
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Introduction• Full-scale Crash Testing• Comparison: blocked vs non-blocked• Rail-Post Attachment• Blockout Importance• Conclusions
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Proprietary Non-Blocked Systems
• T-31 Guardrail (Trinity Highway Products)
• Gregory Mini Spacer Guardrail (Gregory Industries)
• NU-GUARD-31 (Nucor Steel Marion, Inc.)
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Non-Proprietary Non-Blocked Systems
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• Non-Blocked MGS for Wire-Faced Walls of Mechanically Stabilized Earth (TRB 2011)
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Design Details
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MGSNB-1: 62.7 mph @ 24.7 deg
OIV 17.1 ft/s
ORD 11.5 g
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MGSNB-2: 63 mph @ 25.5 deg
OIV 31.3 ft/s
ORD 10.2 g
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Blocked
vs
Non-Blocked
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Pickup Truck
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Blocked Non-Blocked2214MG-2 MGSNB-1
Designation 2270p 2270p
Test Inertial (lb) 5,000 5,011
Speed (mph) 62.8 62.7
Angle (deg) 25.5 24.7
122 115
18" upstream post 12 10" upstream post 13 Impact Point
Impact Conditions
Impact Severity (kip-ft)
Test ComparisonMASH Test 3-11
Test Number
Vehicle
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Pickup Truck
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Blocked Non-Blocked2214MG-2 MGSNB-1
ORD (g's) Longitudinal 8.2 11.5
OIV (ft/s) Longitudinal 15.3 17.1
3.6 2.8
-5 16
posts 13-16 posts 14-15
posts 13-15 posts 14-15
mostly yes
Posts hit by leading tire (wheel snag)
Leading tire/wheel disengaged
Results ComparisonMASH Test 3-11
Test Number
Dynamic Deflection (ft)
Max. Roll Angle (deg)
Posts detached from rail during impact
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Pickup Truck
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Blocked Non-Blocked
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Pickup Truck
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Small Car
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Blocked Non-Blocked2214MG-3 MGSNB-2
Designation 1100c 1100c
Test Inertial (lb) 2,423 2,407
Speed (mph) 60.8 63
Angle (deg) 25.4 25.5
55 59
46" upstream post 14 32" upstream post 14 Impact Point
Test ComparisonMASH Test 3-10
Test Number
Vehicle
Impact Conditions
Impact Severity (kip-ft)
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Small Car
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Blocked Non-Blocked2214MG-3 MGSNB-2
ORD (g's) Longitudinal 16.1 10.2
OIV (ft/s) Longitudinal 14.8 31.3
3 2.4
-13 8
posts 15-17 posts 14-17
posts 15-16 posts 14-17
tire debeaded yes
Posts hit by leading tire (wheel snag)
Leading tire/wheel disengaged
Results ComparisonMASH Test 3-10
Test Number
Dynamic Deflection (ft)
Max. Roll Angle (deg)
Posts detached from rail during impact
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1100c – smoother with blocks
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Blocked Non-Blocked
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Small Car
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Non
-Blo
cked
B
lock
ed
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Advantages of the Blocked MGS• Improved stability for both vehicles• Reduced snag• Reduced occupant risk measures
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Outline• Full-scale Crash Testing• Comparison: blocked vs non-blocked• Rail-Post Attachment• Blockout Importance• Conclusions
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Rail-Post Attachment
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Rail-Post Attachment: 2270p
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Rail-Post Attachment: 1100c
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Blockout Importance
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Blockout Importance
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Post 14: No Wheel Snag Major Wheel Snag
Blocked Non-Blocked
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Blockout does not eliminate wheel snag
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Conclusions and Recommendations
• MGS without blockouts successfully crash tested
• Rail effectively releases from post, even in worst case location
• Blocked system performs better and is recommended if space is available
• Special applications – see report
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