Breakout Session 16: Roadside Safety Countermeasures 2015 Traffic Safety Conference by Chiara Silvestri-Dobrovolny, Associate Research Scientist, Texas A&M Transportation Institute

1. Sign Size
and Breakaway Support
Relationships
Chiara Silvestri Dobrovolny, Ph.D.
Dusty R. Arrington
Roger P. Bligh, Ph.D., P.E.
2015 Traffic Safety Conference
Corpus Christi, Texas
June 10, 2015

2. Order of Presentation
 Objectives
 Literature Review
 Finite Element Computer Simulations
 Full-Scale Crash Testing
 Recommendations

3. Objectives
• Establish Minimum Sign Area for Slip Bases
• Conduct FEA Parametric Study of Impact Performance of
Slip Base Support
• Perform MASH Tests (3-61 and 3-62) as Verification of
FEA Parametric Study

4. Literature Review

5. Texas Slip Base System
10 BWG
Wall τ: 0.134”
55,000 psi min yield
Sch 80
Wall τ: 0.276”
46,000 psi min yield
Texas Slip Base System (2.875” O.D. steel support post)
* TxDOT standards (SMD (SLIP-2)-08)
(Sign areas ≤ 16 ft2)*
 NOT requirement of min sign area w/ slip base
 Texas district practices include use of signs as small as 4 ft2 on Sch. 80
 Motivation behind this practice  reduce inventory and simplify maintenance
(Sign areas ≤ 32 ft2)*

6. Burn Ban Tests
Test #2 Test #3 Test #4
ALL PASSED
Evaluated According to NCHRP Report 350
Evaluate TxDOT practice of appending burn ban sign
to an existing slip base sign support system
according to NCHRP Report 350 criteria

7. BURN BAN Test #2 Videos

8. BURN BAN Test #2
Test #2
5.1”
Occupant Comp. Def.
PASSED (According to NCHRP Report 350)

9. BURN BAN Test #3
Test #3
5.6”
Occupant Comp. Def.
PASSED (According to NCHRP Report 350)

10. BURN BAN Test #4
Test #4
5.5”
Occupant Comp. Def.
PASSED (According to NCHRP Report 350)

11. New criteria for safety
performance evaluation:
MASH
 Required test with Pick-up Truck
 Heavier Pick-up Truck (5,000 lbs)
 Increased vehicle CG
 Occupant compartment deformation ≤ 4”
(cfr. 5.9” from NHCRP Report 350)
Lower Center of Mass of
Sign Support System
(affected by sign mounting
height, sign area and weight)
 Lower center of rotation for sign support
system
 Higher chance to have secondary contact
w/ roof and/or windshield

12. FE Computer Simulations

13. FE Simulations were run with combination of the following:
 10 – 12 – 14 – 16 ft2 Sign Area
 BWG-10 (0.134” τ), Sch 80 (0.276” τ), Sch 40 (0.203” τ) Pipe Support
 Plain and T-Bracket (2 Configurations) Pipe
 1100C (Passenger Car) and 2270P (Pickup-Quad Cab) Vehicles
Simplified FE Matrix

14. Burn Ban Tests
TEST #2
TEST FE
Vehicle Damage
Impact Location
Schedule 80
Total 8 ft2
62 mph
Quarter Point

15. Burn Ban Tests
TEST #3
TEST FE
Vehicle Damage
Impact Location
Schedule 80
Total 10 ft2
62 mph
Quarter Point

16. Burn Ban Tests
TEST #4
TEST FE
Vehicle Damage
Impact Location
BWG-10
Total 10 ft2
62 mph
Quarter Point

17. FE Impact Predictions
w/ Different Sign Areas

18. FE Predictions

19. Full Scale Crash Tests
Recommendations
FE Simulations evaluated w/ respect to:
a) Impact Location
b) Occupant Compartment Deformation
Recommendations:
 MASH Test Level 3-61 (1100C Vehicle), 62 mph
 MASH Test Level 3-62 (2270P Vehicle), 62 mph
 BWG-10 Support
 T-Bracket Pipe
 12 ft2 Sign Area – Square aspect ratio

20. Full Scale Crash Tests

21. Test #463631-1
2270P Pickup-Quad Cab
BWG-10
(2.875” O.D. - 0.134” τ)
T-Bracket
7’ Mounting Height
12 ft2 Sign Area

22. Test #463631-1 Results

23. Test #463631-1 Results
Impact Location: Roof
Occupant Compartment Deformation: 3.75”
Test PASSED
according to MASH

24. Test #463631-2
1100C Passenger Car
BWG-10
(2.875” O.D. - 0.134” τ)
T-Bracket
7’ Mounting Height
12 ft2 Sign Area

25. Test #463631-2 Results

26. Test #463631-2 Results
Impact Location: Roof
Occupant Compartment Deformation: 4.75”
Test FAILED
according to MASH

27. Impact Location

28. Wind Chart

29.  1100C Passenger Car Full Scale Crash Test
(No need for the 2270P Vehicle)
 BWG-10
 (2.875” O.D. - 0.134” τ)
 T-Bracket
 7’ Mounting Height
 14 ft2 Sign Area
Proposed Test Configuration

30. Test #463631-3
1100C Passenger Car
BWG-10
(2.875” O.D. - 0.134” τ)
T-Bracket
7’ Mounting Height
14 ft2 Sign Area

31. Test #463631-3 Results

32. Test #463631-3 Results
Impact Location: Back Roof
Occupant Compartment Deformation: 2.5”
Test PASSED
according to MASH

33. Recommendations

34. Acknowledgements
 Research project conducted under cooperative program between TTI,
TxDOT, and FHWA
 TxDOT project director was Mr. Doug Skowronek
 TxDOT research engineer was Mr. Wade Odell
 Authors acknowledge assistance of project monitoring committee
members:
• Larry Colclasure (WAC)
• Christina Gutierrez (CST)
• Carlos Ibarra (ATL)
• Karl Janak (CST)
• Armen Miskarov (BRG)
• Charlie Wicker (TRF)

35. Questions?
Chiara Silvestri Dobrovolny
E-mail: c-silvestri@ttimail.tamu.edu
Phone: 979-845-8971