midwest guardrail system without blockouts j.d. reid, r.k. faller, r.w. bielenberg, and k.a....

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

2


Introduction

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

3


Proprietary Non-Blocked Systems

• T-31 Guardrail (Trinity Highway Products)

• Gregory Mini Spacer Guardrail (Gregory Industries)

• NU-GUARD-31 (Nucor Steel Marion, Inc.)

4


Non-Proprietary Non-Blocked Systems

5

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


Design Details

6


MGSNB-1: 62.7 mph @ 24.7 deg

OIV

17.1 ft/s

ORD

11.5 g

7


MGSNB-2: 63 mph @ 25.5 deg

OIV

31.3 ft/s

ORD

10.2 g

8


Blocked

vs

Non-Blocked

9


Pickup Truck

10

Blocked Non-Blocked

2214MG-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


Pickup Truck

11

Blocked Non-Blocked

2214MG-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


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


Pickup Truck

12

Blocked Non-Blocked


Pickup Truck

13


Small Car

14

Blocked Non-Blocked

2214MG-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)


Small Car

15

Blocked Non-Blocked

2214MG-3 MGSNB-2

ORD (g's) Longitudinal 16.1 10.2

OIV (ft/s) Longitudinal 14.8 31.3

3 2.4

-13 8



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


1100c – smoother with blocks

16

Blocked Non-Blocked


Small Car

17

No

n-B

lock

ed

Blo

cked


Advantages of the Blocked MGS

• Improved stability for both vehicles• Reduced snag• Reduced occupant risk measures

18


Outline

• Full-scale Crash Testing• Comparison: blocked vs non-blocked

• Rail-Post Attachment• Blockout Importance• Conclusions

19


Rail-Post Attachment

20


Rail-Post Attachment: 2270p

21


Rail-Post Attachment: 1100c

22


Blockout Importance

23


Blockout Importance

24

Post 14: No Wheel Snag Major Wheel Snag

Blocked Non-Blocked


Blockout does not eliminate wheel snag

25


26


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

27

midwest guardrail system without blockouts j.d. reid, r.k. faller, r.w. bielenberg, and k.a....

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