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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Midwest Roadside Safety Facility

Introduction• Full-scale Crash Testing• Comparison: blocked vs non-blocked• Rail-Post Attachment• Blockout Importance• Conclusions

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Midwest Roadside Safety Facility

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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Midwest Roadside Safety Facility

Non-Proprietary Non-Blocked Systems

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• Non-Blocked MGS for Wire-Faced Walls of Mechanically Stabilized Earth (TRB 2011)

Midwest Roadside Safety Facility

Design Details

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Midwest Roadside Safety Facility

MGSNB-1: 62.7 mph @ 24.7 deg

OIV 17.1 ft/s

ORD 11.5 g

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Midwest Roadside Safety Facility

MGSNB-2: 63 mph @ 25.5 deg

OIV 31.3 ft/s

ORD 10.2 g

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Midwest Roadside Safety Facility

Blocked

vs

Non-Blocked

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Midwest Roadside Safety Facility

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

Midwest Roadside Safety Facility

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

Midwest Roadside Safety Facility

Pickup Truck

12

Blocked Non-Blocked

Midwest Roadside Safety Facility

Pickup Truck

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Midwest Roadside Safety Facility

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)

Midwest Roadside Safety Facility

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

Midwest Roadside Safety Facility

1100c – smoother with blocks

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Blocked Non-Blocked

Midwest Roadside Safety Facility

Small Car

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Non

-Blo

cked

B

lock

ed

Midwest Roadside Safety Facility

Advantages of the Blocked MGS• Improved stability for both vehicles• Reduced snag• Reduced occupant risk measures

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Midwest Roadside Safety Facility

Outline• Full-scale Crash Testing• Comparison: blocked vs non-blocked• Rail-Post Attachment• Blockout Importance• Conclusions

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Midwest Roadside Safety Facility

Rail-Post Attachment

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Midwest Roadside Safety Facility

Rail-Post Attachment: 2270p

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Midwest Roadside Safety Facility

Rail-Post Attachment: 1100c

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Midwest Roadside Safety Facility

Blockout Importance

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Midwest Roadside Safety Facility

Blockout Importance

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Post 14: No Wheel Snag Major Wheel Snag

Blocked Non-Blocked

Midwest Roadside Safety Facility

Blockout does not eliminate wheel snag

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Midwest Roadside Safety Facility

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Midwest Roadside Safety Facility

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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