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

Order of Presentation

Objectives

Literature Review

Finite Element Computer Simulations

Full-Scale Crash Testing

Recommendations

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

Literature Review

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)*

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

BURN BAN Test #2 Videos

BURN BAN Test #2

Test #2

5.1” Occupant Comp. Def.

PASSED (According to NCHRP Report 350)

BURN BAN Test #3

Test #3

5.6” Occupant Comp. Def.

PASSED (According to NCHRP Report 350)

BURN BAN Test #4

Test #4

5.5” Occupant Comp. Def.

PASSED (According to NCHRP Report 350)

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

FE Computer Simulations

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

Burn Ban Tests

TEST #2

TEST FE

Vehicle Damage

Impact Location

Schedule 80 Total 8 ft2

62 mph Quarter Point

Burn Ban Tests

TEST #3

TEST FE

Vehicle Damage

Impact Location

Schedule 80 Total 10 ft2

62 mph Quarter Point

Burn Ban Tests

TEST #4

TEST FE

Vehicle Damage

Impact Location

BWG-10 Total 10 ft2

62 mph Quarter Point

FE Impact Predictions w / Different Sign Areas

FE Predictions

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

Full Scale Crash Tests

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

Test #463631-1 Results

Test #463631-1 Results

Impact Location: Roof Occupant Compartment Deformation: 3.75”

Test PASSED according to MASH

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

Test #463631-2 Results

Test #463631-2 Results

Impact Location: Roof Occupant Compartment Deformation: 4.75”

Test FAILED according to MASH

Impact Location

Wind Chart

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

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

Test #463631-3 Results

Test #463631-3 Results

Impact Location: Back Roof Occupant Compartment Deformation: 2.5”

Test PASSED according to MASH

Recommendations

Acknow ledgements

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)

Questions?

Chiara Silvestri Dobrovolny E-mail: c-silvestri@ttimail.tamu.edu

Phone: 979-845-8971