Volume I : Summary Report€¦ · Volume I : Summary Report Research, Development. and Technology Turner-Fairbank Highway Research Center 6300 Georgetown Pike Mclean, Virginia 22101

PERFORMANCE LIMITS OF

LONGITUDINAL BARRIER SYSTEMS

U.S. Department of Transportation

Federal Highway Administration

Volume I : Summary Report

Research, Development. and Technology

Turner-Fairbank Highway Research Center 6300 Georgetown Pike Mclean, Virginia 22101

Report No.

FHWA/RD-86/153

Final Report

May 1986

document is available to the U.S. public through the National Technical Information Service, Springfield, Virginia 2216

FOREWORD

This report, "Performance Limits of Longitudinal Barrier Systems" Volume 1, presents the results of research conducted by the Texas Transportation Institute for the Federal Highway Administration CFHWA>, Office of Safety and Traffic Operations Research and Development under Contract Number DTFH61-82-C-00051. This work was conducted as part of FCP Project 1T, "Roadside Safety Hardware," and is intended for engineers concerned with roadside safety hardware. This work was conducted to evaluate the impact/encroachment performance I imits of selected guardrai Is, median barriers, and embankments through accident data analysis, computer simulation, measurement of inertial properties of vehicles, and ful 1-scale crash tests. The report can provide useful information in selection of a longitudinal barrier system. The longitudinal barriers tested include standard and modified versions of the G4(1S) guardrai I, W-beam rail on wood posts, modified GR-1 three-cable guardrail, modified MB9 median barrier, and 42-inch high concrete median. barrier. Ful 1-scale and computer simulation tests were performed to study embankment traversa Is.

Copies of this report are being given widespread distribution by FHWA Transmittal Memorandum. Sufficient copies of Volume I are being distributed to provide a minimum of one copy to each regional office, division office and State highway agency. Direct distribution is being made to the division offices. Additional copies may be obtained from the National Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 22161.

--J f'in /o._ 3.J m1 Ira--Stanley~. Byington, Director Office of Safety and Traffic

Operations Research and Development Federal Highway Administration

t()TICE

This document Is disseminated under the sponsorship of the Department of Transportation in the interest of Information exchange. The United States Government assumes no I iabil ity for the contents or use thereof.

The contents of th i.s report ref I ect the v i ews of the contractor, who is responsible for the accuracy of the data presented herein. The contents do not necessarily reflect the official pol icy of the Department of Transportation.

This report does not constitute a standard, specification, or regulation.

The United States Government does not endorse products of manufacturers. Trade or Manufacturers' names appear herein only because they are considered essential to the objective of this document.

1. Report No. 2. Government Accession No.

FHWA/RD-86/153 4. Title and Subtitle

Performance Limits of Longitudinal Barrier Systems Volume I - Summary Report

Technical f{eport Documentation P

3. Recipient's Catalog No.

5. Report Date

May 1986 6. Performing Organization Code

~--:---:---;--c:------------------------! 8. Performing Organization Report No. 7

· Authorl s) Buth' c. E. ' Campise' Wanda L. ' Griffin III, L. I., Love, M. L. and Sicking, D. L.

9. Performing Organization Name and Address

Texas Transportation Institute Texas A&M Research Foundation Texas A&M University System

4798 10. Work Unit No. (TRAIS)

51T2-962 11. Contract or Grant No.

DTFH61-82-C-00051 College Station, Texas 77843 13. TypeofReportandPeriadCovered

~12~.-S-p-on-s-or~in~g-A-ge-n-cy_N_a_m_e~an_d_A~d~dr-es_s ________________ ~ Final Report Federal Highway Administration September 1982 to Office of Safety & Traffic Operations R&D May 1985 6300 Georgetown Pike 14. Sponsoring Agency Code

Mclean, VA 22101-2296 15. Supplementary Notes

Contracting Officer•s Technical Representative: Charles F. McDevitt (HSR-20)

16. Abstract

The objective of this study was to evaluate the performance limits of guardrails, median barriers, and embankments for different classes of vehicles and impact conditions.

The study consisted of accident data analyses, computer simulation work, measurement of inertial properties of vehicles, full-scale crash tests of longitudinal barriers, and full-scale embankment traversal tests.

The report consists of five volumes: Volume I - Summary Report Volume II - Appendix A: Vehicle/Barrier Geometries Volume III - Appendix B: Details of Crash Tests on Longitudinal Barriers Volume IV - Appendix C: Details of Embankment Traversal Tests Volume V - Appendix D: Computer Simulations

17. Key Words 18. Oi stribution Statement

Guardrail, Median Barrier, Crash Test, Highway, Computer Simulation, Embankment, Roadside Encroachment

No restrictions. This document availab throuqh the National Technical Informat Service, Springfield, VA 22161

19. Security Clossif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price

Unclassified Unclassified 108

Form DOT F 1700.7 <8-72l Rep:oduction·ot completed page authorized

METRIC (SI*) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO Sl UNITS APPROXIMATE CONVERSIONS TO Sl UNITS Symbol When You Know Multiply By To Find Symbol Symbol When You Know Multiply By To Find Sy111bol

LENGTH LENGTH "' "'

In Inches 2.54 milllmetres mm - ::: mm milllmetres 0.039 Inches in ft feet 0.3048 metres ~ - _ m metres 3.28 feet ft

d d 0 914 t - "' m metres 1.09 yards yd

y yar s . me res m .,. - k · ml miles 1.61 kilometres km ~ m kilometres 0.621 m1les ml

_ ~ AREA AREA ~ - ~

- mm• mlillmetres squared 0.0016 square Inches in2

in• square Inches 645.2 milllmetres squared mm• • -= = !: m• metres squared 10.764 square feet tt• tt• square feet 0.0929 metres squared m• _ !:!: km• kilometres squared 0.39 square miles mi2

yd• square yards 0.836 metres squared m• "' - .., ha hectores (10 000 m2) 2.53 acres ac

ml2 square miles 2.59 kilometres squared km2 _ -

ac acres 0.395 hectares ha _ :!: MASS (weight) ~. - ~

_,, "" _ - g grams 0.0353 ounces oz

MASS (weight) ~ kg kilograms 2.205 pounds lb - _ Mg megagrams (1 000 kg) 1.103 short tons T

oz ounces 28.35 grams g - -lb pounds 0.454 kilograms .kg ... ~

T short tons (2000 lb) 0.907 megagrams Mg - VOLUME "'

=--- ml millilitres 0.034 fluid ounces fl oz .., ~ .. L lltres 0.264 gallons gal

VOLUME - .. m• metres cubed 35.315 cubic feet tt• - m• metres cubed 1.308 cubic yards yd'

fl oz fluid ounces 29.57 millllltres ml =--gal gallons 3.785 lltres L -ft• cubic feet 0.0328 metres cubed m• .. "' TEMPERATURE (exact) yd3 cubic yards 0.0765 metres cubed m•

oc Celsius 9/5 (then Fahrenheit °F NOTE: Volumes greater than 1000 L shall be shown in m•. "' temperature add 32) temperature

- OF .. °F 32 98.6 212

TEMPERATURE (exact) ~· - - -jo. 1 •• ,? .,. ·1~0 1 • ,· ~~. 1)~0 • 1 , 1,~0.,. ,,2?0,j [ _ ~ -40 -20 o 20 f4o 60 ao 100 =-----=- °C 37 °C

"F Fahrenheit 5/9 (after Celsius °C temperature subtracting 32) temperature These factors conform to the requirement of FHWA Order 5190.1A.

• Sl Is the symbol for the International System of Measurements

TABLE OF CONTENTS Page

INTRODUCTION . •.••••••••••••••••••.•••••..••••••••..••.•••••••••• ~. . • . • • 1

VEHICLE/BARRIER GEOMETRIC$............................................ 2 ACCIDENT STATISTICS................................................... 3

Introduction..................................................... 3 Analysis of FARS Data............................................ 3 Analysis of Texas Accident Data.................................. 8

VEHICLE INERTIAL PROPERTIES ••••••...••••••.••••••.•..•••••••.•...••••• 39 Literature Search .•..••.•.••••••..•••.••.••.••..•••••••••..•....• 39 Estimation of Mass Moments of Inertia .••••••.•..•••••••.•.•.•..•• 40 Measurement of Vehicle Properties ••.••••••••.••..••••••.•••••••.. 46

FULL-SCALE CRASH TESTS OF BARRIERS •.•..•.••••••••.•.••.•••••••••.••••. 53 Standard G4(1S) Guardrail (Tests 4 through 8) •.•••.••.•.•.••••.•. 53 Modified G4(1S) Guardrail (Test 10) ••.••••••.•.••.•••••.•••.•.••• 63 W-Beam Rail Mounted 30-in-High on Wood Posts (Test 9) ••.•...•.••. 64 Modified GR1 Thrie-Cable Guardrail (Tests 2 and 11) ••••••••.•.••• 64 Improved MB9 Median Barrier (Test 12) •••••.•.••••••••••.•.•.••••• 71 42-in High Concrete (Tests 1, 3, 13) •••••••.••..•••••••...••••••• 76

EMBANKMENT TRAVERSAL TESTS ••.•••••.•••.••••••••••••••••.••.•.•.•.•.••• 83 COMPUTER SIMULATIONS.................................................. 88

Embankment Traversal Simulations •••.••••••••••••••••••..•...••••• 88 Longitudinal Barrier Impact Simulations •.•••.••••••••••.•••.••.•• 91

SUMMARY AND CONCLUSIONS ....•.•......•..•.................•........•.•. 96 42-in High Concrete Median Barrier •.•.••••••.••••••••...•.•.••••• 96 G4(1S) Guardrail •.•..•••••••••••.••••••.••.•••••••.••••.•...••••• 96 Improved MB9 Median Barrier ••.••.••••.•••...•••••••••.•.•.••••••• 98 Embankment Traversals •...........•..•.•.........................• 98

REFERENCES. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • . • . • • • • • • • • • • • • • • • • • • • • • • • • • • • 100

iii

Figure 1

LIST OF FIGURES

Percent of drivers injured: interstate- guardrail ..............•.•.........•........... 10

2 Percent of drivers injured: U.S. and State- guardrail .........•...................•.... 10

3 Percent of drivers injured: farm-to-market- guardrail ..•......•..•.........•........... 11

4 Percent of drivers injured: county roads - guardra i 1.................................... 11

5 Probability of driver injury: interstate highway guardrail accidents •••••••••••••••••••••• 13

6 Probability of driver injury: U.S. and State highways guardrail accidents •••••.•••••.••••• 14

7 Probability of driver injury: farm-to-market roads guardrail accidents •••••••••••••••••••• 15

8 Probability of driver injury: county roads guardrail accidents ••••••••••••••.••••••••••••• 16

9 Percent of drivers injured: interstate- bridge ••••••••••••••••••••••••••••••••••••••••• 22

10 Percent of drivers injured: U.S. and State- bridge .........••.......................... 22

11 Percent of drivers injured: farm-to-market - bridge... . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

12 Percent of drivers injured: county roads- bridge ....•........•.........•.•....•.•...... 23

13 Probability of driver injury: _ interstate highways side of bridge accidents •••••••••••••••• 24

14 Probability of driver injury: U.S. and State highways side of bridge accidents .•••.••••••• 25

15 Probability of driver injury: farm-to-market roads side of bridge accidents •••••••.••••••• 26

16 Probability of driver injury: county roads side of bridge accidents ••••••••••••••••••••••• 27

17 Percent of drivers injured: interstate- median barriers •••••••••••••••••••••••••••••••• 34

18 Percent of drivers injured: U.S. and State- median barriers •••••••••••••••••••••••••••• 34

19 Probability of driver injury: interstate highways median barrier accidents •••••••••••••••• 35

tv

Figure 20

21 22

23 24 25 26 27 28 29 30 31 32

33 34 35

36 37 38

39

LIST OF FIGURES (continued)

Probability of driver injury: U.S. and State highways median barrier accidents .••••••.•••• 36 Rectangular solid idealization of vehicle •••••••.•.•.•••.••• 45 Cross section of G4(1S) guardrail used in tests 4 through 8 •.•.••••••.••.•••••.•...•.•••••.•••••.••••• 54 Summary of data for test 4798-4 •••••••••••••••••••.•..••.••• 56 Summary of data for test 4798-5 •.••••••.••.•••••.••.•.•••••• 57 Summary of data for test 4798-6 •••••••••••••••••••••..•••••• 58 Summary of data for test 4798-7 •••••••••.•.••••.••••••••.••• 59 Summary of data for test 4798-8 ••••••••.••••••••••.••••••••• 60 Cross section of guardrail used ~n test 10 ••••••••••••••.••• 61 Summary of data for test 4798-10 •••••••.•••••.•••••••••••••• 62 Cross section of guardrail used in test 9 .••••••.••.•.••.••• 65 Summary of data for test 4798-9 ••.••••••••••.•••••••..•.•••• 66 Cross section of modified GR1, 3 cable guardrail used. in tests 2 and 11 .••••••••••••.••••••.•••.••• 67 Summary of data for test 4798-2~ ••••••••...•••••••.•••••..•• 69 Summary of data for test 4798-11 ••••.•••••.••••••••••.•••••• 70 Cross section of improved MB9 median barrier used in test 12 ..................•.....•..........•. 72 Summary of data for test 4798-12 ••••••••••.•••••.•.••••••••• 74 Details of rail separation ••••••••••••••••••••••••.••••••••• 75 Cross section of 42-in-high concrete safety shape used in tests 1, 3, and 13 ••••••••••••••••••••• 77 Cross section of test barrier installation including simulated portions of highway cross section ••••••••••••••••••••••••••••••••••••••.•••••••• 78

40 Summary of data for test 4798-1 •.•••••••••.••••••••••.••.••• 80 41 Summary of data for test 4798-3 .•••••••••••••.•••••••••••••• 81 42 Summary of data for test 4798-13 •.••••••••••••••••••••••.••• 82 43 Cross section of embankment used for testing ••••.••••..••••• 85 44 Drawing of embankment used in simulations •.••••••••••••••••• 90

v

Table --1

2

3

4

5

6

7

8

9

10 11

12 13 14

15 16 17

LIST OF TABLES

Single-vehicle accidents (on interstate and limited access highways) with fatally injured drivers ( FARS, 1978-1981).. • • • • • • • • • • • • • • • • . • . • • • • . . . . • • . • • • 5 Single-vehicle accidents (on U.S. and State highways, and other major arterials) with fatally injured drivers (FARS, 1978-1981) •••.••••••••.••.••. 6 Single-vehicle accidents (on county roads with fatally injured drivers (FARS, 1978-1981) ••••••••..••••••••• 7 Single-vehicle guardrail/guardpost accidents in Texas (1978-1981) •••••••••••.•.•.•..•••••.•••••...•••.••. 9 Interstate guardrail/guardpost accidents •••••.•••.•••.•••.•• 17 U.S. and State guardrail/guardpost accidents •.••.•••••.••••• 18 FM guardrail/guardpost accidents .•.•••••••••••••••••••••.••. 19 County road guardrail/guardpost accidents ••••••••••••••.•••. 20 Single-vehicle side of bridge accidents in Texas (1978-1981) •••••.••••••.••.••••••.••••••. 21 Interstate side of bridge accidents •••••••••.••••.••••••.••• 29 U.S. and State side of bridge accidents ••••••.••••••••••.••• 30 FM side of bridge accidents •••••••••••.••••••••••••••••••••• 3~ County road side of bridge accidents ••••••••••••••••••••.••• 32' Single-vehicle median barrier accidents in Texas (1981) ••••••••••••••••••••••••••••••••••• 33 I-nterstate median barrier accidents •••••••••••••••.•.•.••••• 37 U.S. and State median barrier accidents •••.••••.•••••.•••••• 38

-Vehicle mass moments of inertia and center-of-gravity heights •.•••••••••••••••••••••••••••••.••• 41

18 Vehicle properties for 1978 Honda Civic ••••••••••••••••••••• 47 19 Vehicle properties for 1979 Ford F150 pickup •••••.••••.••••. 48 20 Vehicle properties for 1979 Dodge B-200 van ••••••••••••••••• 49 21 Vehicle properties for 1982 Chevrolet S-10 pickup ••••••••••. 50 22 Vehicle properties for.1982 Chevrolet C-10 pickup .•••••••••• 51 23 Vehicle properties for 1982 Ford F150 van •••••.••••••••••••• 52 24 Full-scale crash test matrix for G4(1S) guardrail •••••••••.. 55 25 Full-scale crash test matrix for modified

GRl cable guardrail •.•...•••.•••••••••.••••••••••••••••••••• 68

vi

Table 26

27 28 29 30

LIST OF TABLES (continued)

Full-scale crash test matrix for 42-in-high concrete median barrier ••.•••••••..•••.••••••..•••.••••••.•. 79 Full-scale embankment traversal tests .••.•.•••••••••..•••... 84 Simulation matrix variables •.••.•.•••••••••..•.•.••••.•••.•• 89 Maximum roll angle HVOSM computer simulations ••••.•••••.•.•• 92 Simulation results used to establish barrier performance 1 i mi ts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

31 G4(1S) maximum impact speeds to preclude wheel snag and ro 11 over • • • • • • . . • . • • • . . • • • • . • • • • . • . . . • . . • • . • • • • • • • • • • . • . 9 7

vi. i

INTRODUCTION

The objective of this study was to evaluate the performance limits of selected guardrails, median barriers, and embankments for different classes of vehicles and impact/encroachment conditions.

The study consisted of accident data ana lyses, computer simulation work, measurement of inertial properties of vehicles, full-scale crash tests of longitudinal barriers, and full-scale embankment traversal tests. Several guardrail designs were studied including:

• G4(1S), standard and modified versions. 1 W-beam rail at 30-in height on wood posts. • Modified GRl three-cable guardrail. • Improved MB9 median barrier. • 42-in high concrete median barrier.

Test vehicles used in the program ranged in size from an 1,800-lb automobile to an 80,000-lb tractor-trailer; however, not all vehicles were used on each barrier.

Computer simulation studies barrier impacts with automobiles. were used.

included embankment traversals and The -HVOSM and GUARD computer programs

Vehicle properties measurements were performed on a subcontract by the University of Michigan Transportation Research Institute.(l,2) Measurements were made on six vehicles. They included location of center-of-gravity, mass moments of inertia, and suspension properties.

1

VEHICLE/BARRIER GEOMETRICS

This section reports on a portion of the work performed under the

first task of the study. The work consisted of a "parking lot survey" of

vehicles with the objective of observing and recording vehicle/barrier

geometries. Photographs were made of vehicles parked adjacent to

simulated W-beam and thrie-beam guardrails. Single-unit vehicles with

various body styles were included. A total of 100 vehicle/guardrail

combinations were each photographed from three pas i ti ons. These

photographs are presented in appendix A.

2

ACCIDENT STATISTICS

Introduction

In order to determine the severity of accidents involving different roadside features (guardrails, bridge rails, and median barriers), NHTSA•s Fatal Accident Reporting System (FARS) data files and the Texas Accident Data Files were selected for analysis. These files were then subset to include only the following accidents:

t FARS • 1978-1981.

t Single-vehicle accidents. t Wherein the driver was fatally injured.

t TEXAS • 1978-1981.

t Single-vehicle accidents~

Analysis of FARS Data

Four classes or types of vehicle were selected from the FARS files for further analysis:

• Passenger Car

• convertible

• 2-door auto

• 4-door auto

• 3/5 door hatch back

• auto with pickup body

• station wagon

• other auto

• unknown auto

3

• Pickup truck

• Truck

• 10,000-19,000 lb

• 19,001-26,000 lb

• > 26,000 lb

• single truck, weight unknown

• Truck with trailer

The first harmful events in the accidents involving these vehicles were then calculated. Table 1 depicts accidents which occurred on interstate and limited access highways. Table 2 portrays accidents on U.S. and State highways, and other major arterials. Table 3 is limited to accidents on county roads.

If we assume that all vehicles passing along a given class of road or highway are equally likely to strike a particular kind of object, and if we find that fatal guardrail accidents are more prevalent for trucks than for cars, we might reasonably hypothesize that truck/guardrail collisions are more apt to result in death than car/guardrail collisions. Following this line of reasoning, table 1 suggests that trucks with trailers have a problem with guardrails and bridge rails (i.e., passing over bridges). This table also suggests that trucks (10,000 lb +) are overrepresented in guardrail accidents. For dividers no conspicuous differences across vehicle type are observed.

In table 2 the outcomes are less clear than in table 1. However, trucks and trucks with trailers may be having more trouble with guardrails than are passenger cars.

In table 3 no clear differences across vehicles are seen for accidents involving guardrails, bridge rails, and dividers.

4

First Harmful Event ()1 Overturn

Parked Car Curb/Wall Divider Embankment Guard Rail Passing Over Bridge Other Total

Table 1. Single-vehicle accidents (on interstate and limited access highways) with fatally injured drivers (FARS, 1970-1981).

Pickup Truck Passenger Car Truck (10,000 lb +)

f % f % f % -665 (22.3) 189 ( 31 . 9) 20 266 ( 8.9) 45 .( 7.6) 6 154 ( 5.2) 30 ( 5. 0) 2

76 ( 2.6) 10 ( 1. 7) 0 156 ( 5.2) 33 ( 5.6) 5 694 (23.3) 117 (19.8) 23 92 ( 3.1) 14 ( 2.4) 2

876 ~ 154 ~ 9 2979 0 592 0 67

Truck With Trailer f %

163 (27.3) 52 ( 8.7} 9 ( 1. 5) 8 ( 1. 3)

34 ( 5. 7) 176 (29.4)

29 ( 4.9) 127 rh1Ht 598 0

First Harmful Event Overturn Parked Car Curb/l4a 11 Divider

en Embankment Guard Rail Passing Over Bridge Other Total

Table 2. Single-vehicle accidents (on U.S. and State highways, and other major arterials) with fatally injured drivers (FARS, 1978-1981).

Pickup Truck Passenger Car Truck {1 0 '000 1 b + )

f % f % f %

2394 (18.6) 1027 ( 30 .. 0) 130 (42.5) 326 ( 2.5) 78 ( 2.3) 4 ( 1. 3) 439 ( 3.4) 63 ( 1 .8) 7 ( 2. 3) 80 ( 0.6) 9 ( 0.3) 0 ( 0.0)

1095 ( 8. 5) 342 (1 0. 0) 21 ( 6.9) 911 ( 7.1 ) 206 ( 6.0) 27 ( 8.8) 332 ( ,2. 6) 93 ( 2. 7) 4 ( 1. 3)

7299 (56. 7) 1606 (46.9) 113 (36.9) 12876 (100.0) 3424 (100.0) 306 ( 100.0)

Truck With Trailer

f %

348 (45.6) 6 ( 0.8) 5 ( 0. 7) 0 ( 0.0)

62 ( 8.1) 72 ( 9.4) 19 ( 2.5)

251 (32.9) 763 ( 100. 0}

First Harmful Event Overturn Parked Car Curb/Wall

" Divider Embankment Guard Rail Passing Over Bridge Other Total

Table 3. Single-vehicle accidents (on county roads) with fatally injured drivers (FARS, 1978-1981).

Pickup Truck Passenger Car Truck ( 1 0' 000 1 b +)

f % . f % f % -1150 (19.6) 538 (30.9) 55 ( 37. 7)

86 ( 1 . 5) 15 ( 0.9) 1 ( 0. 7) 129 ( 2.2) 17 ( 1 . 0) 3 ( 2 .1) 17 ( 0.3) 1 ( 0 .1} 0 ( 0.0)

485 ( 8.3) 174 (10.0) 8 ( 5 .5) 234 ( 4.0) 38 ( 2 .1} 6 ( 4.1) 127 ( 2.2) 44 ( 2.5) 3 ( 2 .1)

3637 ( 61 . 9) 917 (52. 5) 70 (47,8)

5865 (100.0) 1744 (100.0) 146 ( 100.0)

Truck With Trailer

f %

27 ( 32. 1 ) 1 ( 1. 2) 1 ( 1. 2) 0 ( 0.0) 4 ( 4.8) 1 ( 1. 2) 2 ( 2.4)

48 (57. 1 ) 84 (100.0)

As an aside it should be observed in tables 1 through 3 that all three types of trucks are more subject to overturn than passenger cars.

Analysis of Texas Accident Data

Three classes of vehicles were chosen from the Texas accident files by selecting on a variable referred to as "vehicle type."

• Passenger Car. • Truck (including pickups). • Tractor and semitrailer.

Table 4 is a breakdown of driver 1nJury as a function of vehicle type and highway class for accidents involving guardrails/guardposts. This table indicates, for example, that 5,430 drivers of passenger cars collided with- guardrails on interstates and were not injured (0); 843 received possible injuries (C); 1,698 received nonincapacitating injuries (B); 487 received incapacitating injuries (A); and 89 received fatal injuries (K).

Similar distributions of injury are provided for drivers of trucks (T) and tractors and semitrailers· (S). The right-most columns in this table provide statistical tests to determine if the injury distributions differ across vehicles, overall. Ad hoc statistical tests of differences among the three pairings of vehicles are also provided.

Figures 1 through 4 depict the percent of drivers who received minor (possible) or greater injuries (C+); moderate (nonincapacitating) or greater injuries (B+); serious (incapacitating) or greater injuries (A+), These figures are further separated according to vehicle type (C passenger cars; T, trucks; S, tractors and semi tra i 1 ers) and hi ghwa~ class. To the extent that the "functions" in these figures ar1 horizontal, vehicle type does not affect driver 1nJury outcome Deviations from the horizontal in these functions reflect the differentia· severity of ace i dents i nvo 1 vi ng different types of veh i c 1 es -- and/ o chance error. 8

Highway Driver Class Injury

Interstate a c B A K

U . S . and State a c B A

\0 K

Farm to ~1arket a c B A K

County Roads a c B A K

Table 4. Single-vehicle guardrail/guardpost accidents in Texas (1978-1981).

Vehicle Ty~e Differences in the Severity Passenger- Tractor and of Driver Injury Among Car {C) Truck { T) Semitrailer (S) Vehicle T~~es (a=a.a5)

543a 1367 486 avera 11 s 843 2aa 86 s vs. c s

1698 479 146 T vs. C s 487 145 61 S vs. T NS

89 32 22

3652 la86 276 avera 11 s 58 a 192 52 s vs. c s

la77 378 84 T vs. C s 346 162 4a S vs. T NS 96 52 12

588 274 32 avera 11 s 1 a2 55 9 s vs. c NS 196 125 la T vs. C s

92 64 7 S vs. T NS 31 13 4

169 82 2 avera 11 NS 28 5 1 s vs. c 54 21 a T vs. C 15 1a 1 S vs. T 5 4 a

__, 0

INTERSTATE - GUARDRAIL

50

"0 40 ~C+ <LI ~ :::1

'r-")

s:: 1-4

II) ~ <LI > 30 .,....

~B+ ~ Cl

t+-0

.!-) s:: <LI u ~ 20 <LI

0...

JO .-/A+

c T s Figure 1. Percent of drivers injured:

interstate- guardrail.

U.S. and STATE - GUARDRAIL

50

"0 401 /C+ <LI S;.. :::1

'r-")

s:: 1-4

II) ~

301 <LI

~B+ > .,.... ~ Cl

t+-0

.!-) s:: <LI u ~ 20 <LI

0...

10 ~A+


U.S. and State- guardrail.

.......

.......

FARM TO MARKET - GUARDRAIL so, rC+ 40

"'C Q)

0Bt s... ::s .,..., s::

1-1

Vl s... Q) 30 > .,.... s...

Cl

'6 ......, s:: Q)

20 u s... Q) /At 0...

10-1


farm-to-market- guardrail.

COUNTY ROADS - GUARDRAIL 50

40-1 I C+ "'C Q) s... ::s .,..., s::

1-1

Vl s... ~ 30 .,....

I ----~ s... B+ Cl

If-0

......, s:: ~ 20 s... Q)

c..

I I A+

10


county roads guardrail

Figures 5 through 8 are logistic regression functions depicting probability of driver injury in passenger cars as a function of curb weight. The top-most functions represent minor or greater injury (C+); the middle function represents moderate or greater injury (B+); the bottom function represents serious or greater injury (A+). The four different figures depict accidents on four different classes of highway.

The following table summarizes the findings from these figures. The letter "S" means the function differs significantly from the horizontal; "NS 11 indicates that the function is not significantly different from horizontal.

Injur~ Level Highwa~ Class C+ B+ A+ Interstate s s NS U.S. and State s s NS Farm to Market s s NS County Roads NS NS NS

The information in this table is further detailed in tables 5 through 8.

Table 9 depicts accidents involving vehicles striking the sides of bridges and is similar in format to table 4. Note that significant overall differences are seen in the severity of driver injury for accidents occurring on interstates, w.s. and State highways, and farm-to-market roads. Significant differences in the severities of driver injury for different vehicle pairing are also shown in the table.

Figures 9 through 12 are similar to figures 1 through 4. It is interesting to note that tractors and semitrailers seem to be a serious disadvantage in bridge rail collisions on interstates (figure 9) and U.S. and State highways (figure 10).

Figures 13 through 16 are logistic regression functions depicting the probability of driver injury as a function of passenger car curb weight.

12

-...._ .30

.20

.1 0

INTERSTATE HIGHWAYS GUARD -RAIL ACCIDENTS

-------......... --..._ ...__

------- ---..-.. __ __ -- ........ ------......... __

------------------------------------

0. 0 L...L...&...I....I...I....I...L ......... L...L....L...L...&...I....&..&....I...L....J...:L...L....L-I...r....&....&..&.....I....L....J...:L...L...I....L...&...I 0 ~ ~ ~ ~ ~ 0 0 ID ~ ~ M 0 ~ 0 ID ~ 0 ID ~

~ ~ M ~ ~ ~

Passenger Car Curb Weight[lbs]

Figure 5. Probability of driver injury: interstate highway guardrail accidents.

13

:>, ~ :=;j .,_., ~ ...... ~ .30 (!) :>

•..-! ~

t=:l "H 0

:>, +-' •.-I ........ •..-! ,.0 a:l

,..0 0 ~ p..,

-

U.S. AND STATE HIGHWAYS GUARD RAIL ACCIDENTS

-------------------------------------- ....... __ -----~-----------------------

-------------------------


Figure 6. Probability of driver injury: U.S. and State highways guardrail accidents.

14

>.. ~ ;::l . ......, ~ -~

~ ..... ~

~ "H 0

>.. -j-.J ....... -....... ..0 (t:J

..0 0 ~

0-.

.20

.1 0

FARM TO MARKET ROADS GUARD RAIL ACCIDENTS

----------------------------...... __

----------

------------

------------------------------------

o. 0 0~.1...1..~...1...1.~1....1-'-I...L...L..L...L...I...I...J....JU..L.J...C"l~.L...L....I....I...&...J....J~U..L-L.J 0 ("') ,.... 0 (X)

-.:!" ~

Passenger Car Curb Weight(lbs]

Figure 7. Probability of driver injury: farm-to-market roads guardrail accidents.

15

>... ~ ::;:! .,......., ~ ...... ~ (])

> ....... ~

~

tt-l 0

>... +l •.-l -....... ..0 d

..0 0 ~

~

.40

.30

.20

-- .... --

COUNTY ROADS GUARD RAIL ACCIDENTS

-__ _..

------------_ _..

---_ _.. _..- -_ ....

------------------------___ ... ______ _

~ 00 ~ ~ M N 00 ~ ~ ~ M N 0 ~ 00 N 0 ~ 00 N N N M ~ ~ ~


Figure 8. Probability of driver injury: county roads guardrail accidents.

16

0 0 N I()

Table 5. Interstate guardrail/guardpost accidents.

Minor Injury ~1oderate Injury Serious Injury or Greater or Greater or Greater

(A,B,C,K) (A,B,K) (A, K)

Drivers Injured 2446 1785 444

Drivers Not Injured 4234 4895 6236

Total 6680 6680 6680

Pr (Driver Injury) .3662 .2672 .0665

Min. Curbweight 1356 1356 1356

Max. Curbweight 5388 5388 5388

Mean Curbweight 3358o23 3358.23 3358.23

Injury Level Variable Coefficient Std. Error Chi-Sq. Pr

Minor Injury Intercept -0.09235141 0.11236560 0.68 0.4111

or Greater Curbweight -0.00013633 0.00003280 17.27 0.0000

Moderate Injury Intercept -0.48333344 Ool2153781 15o82 o. 0001

or Greater Curbweight -0.00015750 Oo00003571 19o46 0.0000

Serious Injury Intercept -2.72031046 Oo21902859 154.25

or Greater Curbweight Oo00002320 0.00006333 Oo13 0.7142

17

Table 6. U.S. and State guardrail/guardpost accidents.


(A,B,C,K) (A,B,K) (A, K)



Total 4449 4449 4449

Pr (Driver Injury) o3641 .2623 .0757



Mean Curbweight 3414.65 3414.65 3414.65

Injury Level Variable Coefficient Std. Error Chi-Sqo Pr

Minor Injury Intercept -0.08612490 - 0.14057800 0.38 0.5401

or Grea·ter Curbweight -0. 00013849 Oo00004040 11.75 0.0006

Moderate Injury Intercept -0.60242653 0.15284285 15.54 0.0001

or Greater Curbwei ght -0.00012706 0.00004409 8.30 0.0040

Serious Injury Intercept -2.31573233 0.25434945 82.89

or Greater Curbweight -Oo00005465 0.00007321 0.56 0.4554

18

Table 7. FM guardrail/guardpost accidents.

Minor Injury f~oderate Injury Serious Injury or Greater or Greater or Greater

(A,B,C,K) (A,B,K) (A, K)



Total 767 767 767

Pr (Driver Injury) .4237 .3220 .1160



Mean Curbweight 3451.23 3451.23 3451.23


Minor Injury Intercept 0.05857540 0.34134342 0.03 0.8638




Serious Injury Intercept -2.00345792 0.52699860 14.45 0.0001

or Greater Curbweight -0.00000.784 o. 00014931 0.00 0.9581

19

Table 8. County road guardrail/guardpost accidents.


(A,B,C,K) (A,B,K) (A, K)



Total 202 202 202

Pr (Driver Injury) .3614 .2673 .0842



Mean Curbweight 3442.99 3442.99 3442.99


Minor Injury Intercept -1.44374639 0_. 6464787 4 4.99 0.0255

or Greater Curbweight 0.00025218 0.00018027 1. 96 0.1618

Moderate Injury Intercept -1.53361433 0.69654302 4.85 o. 0277

or Greater Curbweight 0.00015153 0.00019422 0.61 0.4353

Serious Injury Intercept -2.29902097 1. 07849204 4.54 0.0330


20

Table 9. Single-vehicle side of bridge accidents in Texas (1978-1981}.

Vehicle T~pe Differences in the Severity Highway Driver Passenger Tractor and of Driver Injury Among Class Injury Car (C) Truck ( T) Semitrailer (S) Vehls~Types (a=0.05)

Interstate 0 1737 418 158 Overa 11 s c 268 64 26 s vs. c s B 510 130 54 T vs. C s A 166 54 36 S vs. T s K 29 12 19

U.S. & State 0 1863 628 133 Overa 11 s c 273 92 18 s vs. c s B 519 184 42 T vs. C NS

N A 207 77 23 S vs. T NS ...... K 44 23 7

Fa m to Market 0 313 161 14 Over-a 11 s c 51 23 0 s vs. c NS B 112 65 2 T vs. C s A 41 45 0 S vs. T s K 15 12 l

County Roads 0 255 150 4 Overa 11 NS c 40 27 1 s vs. c B 83 57 2 T vs. C A 47 21 1 S vs. T K 13 7 0

50 ..,

"0 40 CLI ~ ::s .,..., s:: ....... (f)

~ CLI > 30 .,... ~

Cl

If-0 ....,

N s:: N CLI

u 20 ~ CLI

a..

10 1

Figure 9.

INTERSTATE - BRIDGE

C+

/ B+

/A+ ~

c T s Percent of drivers injured: interstate - bridge.

U;S. and STATE - BRIDGE

50

"0 40 /C+ CLI ~ ::s .,..., s:: .......

~ 30 ~ /H+ If-0 ...., s:: CLI u ~ 20 CLI a..

I 10 1

/A+


U.S. and State - bridge.

N w

FARM TO MARKET - BRIDGE 50

C+

"0 40 QJ s-::I ... s:: ~

II)

B+ s-~ 30

•r-s-

Q

4-0

.f..J s:: ~ 20 s...

1\ QJ a..

A+

10 i \


farm-to-market - bridge.

50 COUNTY ROADS - BRIDGE

C+ I

"0 40

QJ

J s-::I . .. s:: B+ ~

II)

s-~ 30

•r-s-Cl

4-0

+-> s:: QJ 20 u s-QJ

a..

~ A+ 10


county roads - bridge.

l~TERSTATE HIGI-IWAYS SIDE OF BRIDGE ACCIDENTS

.so~, c • 1 c • • 1, c , 1 1 , o 1 c 1 o 1 1 c c 1, c c 1 c 1 1 1 c o c~

J

----------------------------------------------- -----

.I 0 [------------------------------------

0.0 0 <I' <D ("') "" 0 0 en ,_

("') "" - 0 1'- 0 ~ 0 '<!- ()') "" "" '" <l '<!- -.! on

Passenger Car C-;J.rb Weight[lbs] Figure 13. Probability of driver injury: interstate highways

side of bridge accidents.

24

....... 0

!>-. -o-1 ...... -

U.S. AKD STATE HIGHWAYS SlDE OF BHlDGE ACCIDENT~

.40rr~•••~;~.~.r,~1 ~t•l~.-1~,~.~~~~~.~, rt~1 ~,~~~~~~~~~~~1•j~l~i~l~j~i~i~t~

------------------------

-------------------------------

0 · 0 o_L...L....L....I....I"'-'-.L....i....l..nl...L....I.-i-L..L....i.-I....I<D-'-L..L...L-I.....I...J~.L..I....&...J"'-'-L..L..L.I.....L-JL....Jo 0 ~ ~ ~ N - 0 ~ 0 ~ N V 00 N

N N M v V ~

Figure 14.

Passenger Car Curb Weighl[lbs]

Probability of driver injury: U.S. and State highways side of bridge accidents.

25

FARM TO MARKET ROADS SIDE OF BRIDGE ACCIDENTS

.5ll ' I I I ' ' I I I I I ' I I I ' I I I I I I I I I I I I I I I I I I

---L ------------c .4l ~ ~ .__, ~ ~ ~ .3o[: __ -------------------------> ....... s-o

'l t

~ ------.10- -~-1 ~-~---~-~ ' ---r-----

---------

I 0.0

0 0'· U1 ,.... 0 fX) r·. <0 -~- 0 " fX) aJ ~ !'< !'< !'< v

0 0 !'< I()

Figure 15.


Probability of driver lnJury: farm-to-market roads side of bridge accidents.

26

! ' t !

COUNTY ROADS SIDE OF BRIDGE ACCIDENTS

(),C L._.__._ ~~r.L..i. ' I I j j I I : j ~ I I j ~ I I i I f I I I I J I I I I

0 ~ ro ~ ~ ~ M N

; b ~ ~ ~ ~ 8 ~ - 'i'l ~ ,.....: ~ ·::t ~

Passen~:er Car Cur-o Weight[1hs]

0· 0 N I()

0

Figure 16. Probability of driver injury: county roads side of bridge accidents.

27

The following table indicates which functions deviate significantly from horizontal.

Highway Class Interstate U.S. and State Farm-to-Market County Roads

Injury Level C+ B+ A+ S NS NS

NS NS NS NS NS NS NS NS NS

Tables 10 through 13 provide further information regarding these logistic regression functions.

Table 14 is similar to table 4. Note, however, that this table is based upon only 1 year of accident data (1981) and two highway types -interstate, and U.S. and State. No significant differences were observed among the driver injury distributions for three vehicle types.

Figures 17 and 18 are drawn in the format of figures 1 and 2. The sample sizes, however, are relatively small and figures should be interpreted accordingly.

Figures 19 and 20 are logistic regression equations similar to figures 5 and 6. None of these six equations deviate significantly from the horizontal. Additional information on these equations is provided in tables 15 and 16.

28

Table 10. Interstate side of bridge accidents.

Minor Injury f1oderate Injury Serious I;;jury or Greater or Greater or Greater

(A,B,C,K) (A,B,K) (A,K)


Dr1vers Not Injured 1420 1630 2033

Total 2183 2183 2183

Pr (Driver Injury) .3495 .2533 .0687

Min. Curbwei9ht 1566 1566 1566


Mean Curbweight 3360.77 3360.77 3360.77


Minor Injury Intercept -0.16466196 o. 19384153 0.72 0.3956






29

Table 11. U.S. and State side of brid9e accidents.


(A,B,C,K) (A,B,K) (A,K)



Total 2288 2288 2288

Pr (Driver Injury) .3619 .2666 .0835



Mean Curbweight 3437.23 3437.23 3437.23


Minor Injury Intercept -0. 58466641 o. 19668378 8.84 0.0030

or Greater Curbweight 0.00000509 0.00005579 o. 01 0.9273


or Greater Curbweidht 0.00004787 0.00006074 0.62 0.4306



30

Table 12. FM side nf bridge accidents.


(A,B,C,K) (A,B,K) (A, K)



Total 404 404 404

Pr (Driver Injury) .4208 3094 • 1039

Min. Curbwei9ht 1725 1725 1725


Mean Curbweight 3479.37 3479.37 3479.37

Injury Leve 1 Variable Coefficient Std. Error Chi-Sq. Pr

Minor Injury Intercept -0.43212032 0.47638459 0.82 0.3644

or Greater Curbweight 0.00003235 o. 00013371 0.06 0.8088


or Greater Curbweight 0.00005270 0.00014303 0.14 0. 7125



31

Table 13. County road side of bridge accidents.


(A9B,C,K) (A,B,K) (A, K)



Total 333 333 333

Pr (Driver Injury) .3994 .3003 .1171



Mean Curbweight 3450.54 3450.54 3450.54


Minor Injury Intercept 0.35168380 .0.52191927 0.45 0.5004


Moderate Injury Intercept 0.15211176 0.54967798 0.08 0.7820


Serious Injury Intercept -1.19303159 o. 76229897 2.45 0.1176

or Greater Curbweight -0.00024344 0.00022221 1.20 012733

32

Table 14. Single-vehicle median barrier accidents in Texas (1981).

Vehicle T~pe Differences in the Severity Highway Driver Passenger Tractor and of Driver Injury Among Class Injury Car (C) Truck ( T) Semitrailer (S) Vehicle Ttpes (a=0.05}

Interstate 0 487 150 34 Overa 11 NS c 86 24 8 s vs. c B 214 46 14 T vs. C A 48 18 1 S vs. T

w K 11 2· 0 w

U . S . and State 0 253 84 20 Overa 11 NS c 45 10 4 s vs. c B 84 33 4 T vs. C A 33 8 2 S vs. T K 1 1 0

w ..p-

INTERSTATE - MEDIAN BARRIERS

50

Vc• -c 40 QJ s... ::I .,..., c ...... Vl s...

~B+ QJ > .,... 30 s... Cl

4-0

+l c QJ u s... 20 QJ

0..

10

\A+ c T s

Figure 17. Percent of drivers injured: interstate - median barriers.

U.S. and STATE - MEDIAN BARRIERS

50

-c QJ 40 s...

~C+ ::I .,..., c ...... Vl s... QJ > .,...

30 s... Cl

4-0

+l c QJ u s...

20 I II B+ QJ 0..

10 .____A+ c T s

Figure 18. Percent of drivers injured: U.S. and State - median barriers.

INTERSTATE HIGHWAYS MEDIAN BARRIER ACCIDENTS

.50~TI~i~j~l~.~.~1rri TJTi~j~l~i~l~j~JTI~i~j~i~i~l~j~ITI~I~J~i~l~i~j ~1~1~1 1

--------.40,_

--------------..--.._ -----------------

------- .... --- .... - --------------

0.0 0 <I' Q) " <.0

"'" :'1 N 0

0 CD r-- 10 1/)

"'" C"l N - 0

r-- 0

"'" Q) N 10 0

"'" Q) N - N N N C"l M '</"

"'" '<t 10

Passenger Car Curb Weighl[lbs]

Figure 19. Probability of driver injury: interstate highways median barrier accidents.

35

U.S. AND STATE HIGHWAYS MEDIAN BARRIER ACCIDEKTS

.50 I I I i I I I I I I I I I I I I I I I I I I I I I I I I

----------

Figure 20.

----------

---

,----.,.-. ,-

------------

Passenger Car Curb Wei.ght[lbs]

Probability of driv~r inj~ry: U.S. and State highways median barrier ~C:CJ.dents.

36

Table 15. Interstate median barrier accidents.

Minor Injury Moderate Injury Serious Injury or Greater or Greater or Greater

(A,B,C,K) (A,B,K) (A, K)


Drivers l'iot Injured 378 453 622

Tota 1 663 663 663

Pr (Driver Injury) .4299 .3167 .0618



Mean Curbweight 3240.84 3240.84 3240.84

Injury level Variab1 e Coefficient Std. Error Chi-Sq. Pr

Minor Injury Intercept -0.18792868 0.33258543 0.32 0. 5720

or Greater Curbweight -0.00002916 0.00009981 0.09 0. 7701





37

Table 16. U.S. and State median barrier accidents.

Minor Injury t1odera te Injury Serious Injury or Greater or Greater or Greater

(A,B,C,K) (A,B,K) (A,K)



Total 317 317 317

Pr (Driver Injury) .3785· .2618 .0662



Mean Curbweight 3270.43 3270.43 3270.43

Injury Leve 1 Variable Coefficient Std. Error Chi-Sq. Pr

Minor Injury Intercept 0.21437357 0.49419585 0.19 0.6644

or Greater Curbwclght -0.000?.1fl?1 o. oooliHns 2.16 0.1/ll:l



Serious Injury Intercept -4.07899104 1.05094859 15.06 0. C(}J1

or Greater Curbweight 0.00042362 o.onn?.q~: .: 2.06 0. "j 492

38

VEHICLE INERTIAL PROPERTIES

A search of the literature was made to locate and summarize reported vehicle inertial and related properties. Also, inertial and selected suspension properties of six vehicles were measured by the University of Michigan Transportation Research Institute (UMTRI).

Literature Search

Reported measurements of vehicle inertial properties were found to be very limited in number and availab-le from only a few sources. A large portion of the reported values were found in reports from the University of Michigan, Southwest Research Institute, and Dynamic Sciences, Inc.

Equipment at the University of Michigan used to measure inertial properties is rather sophisticated and versatile.(3) The device used is capable of measuring inertial and center-of-gravity properties on vehicles ranging in size from the smallest automobiles to large buses and tractor-trai 1 er trucks. For the inertia 1 measurements a 1 arge frame on which the vehicle is rigidly attached is suspended on four wire ropes from an overhead structure. Yaw, pitch, and roll mass moments of inertia are measured by measuring the period of oscillation of this compound pendulum in three different modes. The location of the center-of-gravity of a test vehicle is obtained by balancing the vehicle-frame system on a knife edge and measuring the angle of inclination for a range of input torques at the pivot point.

Equipment at Southwest Research Institute used to measure inertial and center-of-gravity properties is similar to that used at HSRI, exceot that the vehicle is not supported on a platform. (4) For measurement ~f the mass moment of inertia in yaw the vehicle is suspended by cables from a rigid overhead fixture. This vehicle-fixture system constitutes a simple torsional pendulum. A separate fixture is used to measure pitch and roll mass moments of inertia. This fixture consists of rigid links connecting the vehicle to an overhead beam, about \'thich axis the system

39

oscillates. The center-of-gravity location is determined by weighing the vehicle at different angles of inclination.

Equipment used by Dynamic Science, Inc. (DSI) to measure inertial properties consists of two devices. One is designated the Fixed Parametric Measurement Device (FPMD) and the other the Mobile Parametric Measurement Device (MPMD). (5,6) Both devices are identical in concept for measurement of inertial and center-of-gravity properties, differing only in the size of the vehicle they are capable of accommodating. The MPMD is mounted on a flatbed trailer and is designed to measure properties of vehicles weighing up to 10,000 lb (4,540 kg) while the FPMD is a permanent installation intended to measure vehicles which are heavier than 10,000 lb or larger than the MPMD can accommodate. Both devices consist of a frame supported on a spherical bearing to which the vehicle is rigidly attached. For measurement of each of the three mass moments of inertia, the vehicle (and frame) is restricted to a rotation about an axis and is allowed to oscillate with mechanical springs providing restoring forces. The period of oscillation and certain geometries are used to arrive at the primary mass moments of inertia. The center-of-gravity location can be determined during measurement of the pitch mass moment of inertia or measured in a separate procedure. The center-of-gravity location can be defined during the measurement of the pitch mass moment of inertia.

A listing of the mass moments of inertia and center-of-gravity heights found in the literature survey is given in table 17.

Estimation of Mass Moments of Inertia

Computations of mass moments of inertia for regular-shaped objects of uniform density are readily accomplished. For a rectangular solid of unequal dimension, such as shown in figure 21, the formulas are:

I = 1/12 M (a2 + b2) XX

I = 1/12 M (a2 + i2) yy I = 1/12 M (b2 + i2) zz

40

Table 17. Vehicle mass moments of inertia and center-of-gravity heights.

VEHICLE MASS MOMENTS OF INERTIA (lbf-ft-sec 2 )

Weight CG Ht I Iyy 1zz XX

( 1 b) (in) ( ro 11) (pitch) (yaw)

1974 Chevy Vega 2,281 21.8 608 1,658 1,333 Chevy Vega 2,244 221 - 1,240 Leyland Mini 1,650 125 - 472 Leyland 1800 3,300 295 - 1,476 Fiat 850 85 - 583 Datsun Bluebird 140 - 1,033 Volvo 164 321 - 1,948 BMW 2800 350 - 2,151 Austin America 1,300 229 - 1,018 Ford Cortina MK2 181 - 1,262 Ford Galaxie 4,356 443 - 4,169

1963 Ford Galaxie 4-DR Sedan 4,180 500 2,500 3,000

1953 Buick 4,124 466 2,800 3,089 1976 Honda Civic 1,509 19.5 150 496 667

Large Sedan 4,500 27.0 - 4,625 4,167 Chevy Nova 4-DR 3,773 19.03 - 2,606 -

1980 RWD GM Compact 3,593 20.8 310 2,245 2,294 1980 FWD GM Compact 2,637 21.14 275 1,503 1,604 1971 Chevy Impala 3,915 21.82 809 4,666 5,179 1979 Chevette 2 DR 2,196 19.44 289 1,118 1,151 1978 AMC Pacer

Wagon 3,369 23.28 441 1,891 2,184 Chevy Nova 4-D~ 3,773 19.03 - 2,606 -AMC Pacer 2-DR 3,275 21.38 - 1,690 -

41

REFERENCE

7 8 8 8 8 8 8 8 8

8 8

9 9 10 10

11

12 12 13 14

14 11

11

Table 17. Vehicle mass moments of inertia and center-of-gravity heights (continued).

AMC Concord 2-DR 3,244 21.14 - 1,977 -AMC Spirit 4-DR 3,125 21.00 - 1,500 -AMC Jeep CJ-5 2,852 26.45 - 871 -AMC Jeep CJ-7 2,756 24.8 - 988 -AMC Eagle 2-DR (4WD) 3,448 22.64 - 1,933 -Ford Bronco 3,793 27.19 - 1,768 -Ford F250 P/U 4,459 29.32 743 4,266 4,065

1974 Chevy Blazer (4WD) 5,005 27.14 - 3,302 -

1970 Ford/Wayne School Bus 12,840 39.2 5,000 49,300 49,250

1969 Chevy/ Bluebird School Bus 13,780 40.8 5,667 51,580 48,500 Utility Bus 20,000 41. 5,660 51,600 48,000 Ford School Bus 26,000 47.74 - 66,800 -Ford School Bus 15,000 43.80 - 57,400 -

1955 GCM Sceni-cruiser Bus 28,200 55.8 22,900 158_,300 125,000 Large Inter-city Bus 40,000 55.8 23,000 156,500 125,000 I.H. Tractor (Sprung Mass Only) 10,316 39.70 1,514 5,833 5,833 Ford Tractor (Sprung Mass Only) 10,331 43.68 1,500 6,181 6,181 C.O.E. Tractor {Sprung Mass Only) 7,990 44.00 992 4,120 4,120 GMC 6500 V-8 Tractor 11,920 35.43 - 10,970 -

42

11

11

11

11

11

11

15

11

7

7 10

11

11

7

10

15

15

15

11

Table 17. Vehicle mass moments of inertia and center-of-gravity heights (continued).

GM ASTRO 95 Dump Truck 15,749 38.83 - 14,713 -Ford 9000 Flat Bed 17,850 37.61 - 15,597 -Freightliner Tractor 17,194 37.61 - 28,447 -GMC 8500 V-6 Packer Truck 18,000 55.25 5,950 39,733 37,792 REX Concrete Mixer 23,600 58.33 7,958 42,083 44,708 GM Medium Duty Van Truck 9,380 44.25 5,150 24,733 25,692 White 6 X 4 Tractor 14,270 39.75 3,000 14,897 -

43

11

11

11

11

11

11

11

The estimation of mass moments of inertia for vehicles is more difficult; however, due to their irregular shapes and uneven distribution of masses. A report by Basso surveyed the literature and reported the published values of measured vehicle inertial properties.( 17) It also gave experimentally derived expressions that relate inertial properties to a more easily measured value such as total vehicle weight:

For total vehicle weight:

I (YAW) = 1.82 WT zz Iyy (PITCH) = 1.57 WT

For vehicle sprung weight:

where

Izz (YAW) = 1.57 Ws IXX (ROLL) = 1.54 Ws

(YAW-ROLL) = 0.0374 Ws Q

1. 67 tan (2A)

WT = Total vehicle weight (lb) Ws = Vehicle sprung weight (lb) g = acceleration of gravity " = inclination of principle axis I = inertia (1bf - ft - sec2)

Another reference suggests the fo 11 owing models for heavy and 1 arge vehicles:< 18)

Izz (YAW) = 1.5 (WT/12g) (12 + w2) Iyy (PITCH) = 1.1 (WT/12g) (12 + h2)

IXX (ROLL) = (WT/12g) (w2 + h 2) where

1 = overall length of vehicle (ft) w = overall width of vehicle (ft) h = overall height of vehicle (ft) I = inertia (ft - lbf - sec2)

44

l

t~ :- ~In ss a = Heiqht b = Width .e. = Lenqth

Figure 21. Rectangular solid idealization of vehicle.

45

Note that both of these approximate methods are based on total vehicle weight.

Measurements of Vehicle Properties

Inertial and selected suspension properties of six vehicles were measured by the University of Michigan Transportation Research Institute (UMTRI). This activity and the results obtained are summarized here. Further details are contained in Winkler•s reports. (1,2)

A 1978 Honda Civic, a 1979 Dodge B-200 van and a 1979 Ford Fl50 pickup truck were purchased by UMTRI for use in measuring inertial properties and were later furnished to Texas Transportation Institute for use in the crash testing program. A 1982 Chevrolet S-10 pickup, a 1982 Chevrolet C-10 pickup, and a 1982 Ford F-150 van were leased by UMTRI for measurement of inertial properties and were subsequently returned to the owners. Properties for these six vehicles are presented in tables 18 through 23.

46

Table 18. Vehicle properties for 1978 Honda Civic.

Weight (lb)

Wheelbase (in)

Vertical C. G. Position

Above Ground (in) Above Vehicle Ref., h(in)

Longitudinal c. G. Position

1699

86.25

20.38 13.1

Aft of Front Axle Center, a (in) - 31.75

Principal Moments of Inertia (in-lb-sec2)

Roll, Ixx 2119

Pitch, Iyy 8652

Yaw, Izz 7828

Upsprung Mass Locations

hf {in) 2.9

hr (in) 3.0

a (in) 31.75

Effective front unsprung weight without spring, one side: (lb) 87

Front spring weight, one side: (lb) 4-1/2

Effective rear unsprung weight without spring, one side: (lb) 67

Rear spring weight, one side: (lb) 3-1/2

Note: Unsprung weights include upper (fixed in sprung mass) strut parts. Estimated weight of these parts is between 1 and 2 1 bs. No addition shou 1 d be made to these numbers to account for a portion of the spring.

47

Ref.

Table 19. Vehicle properties for 1979 Ford F150 pickup.

Weight (lb)

Wheelbase (in)

Wheelbase Wll


Above Ground (in) Above Vehicle Ref., h (in)

Longitudinal C. G. Position

3863

132

26.09 10.22

Aft of Front Axle Center, a (in) 56.09


Roll, Ixx

Pitch, Iyy

Yaw, Izz


hf (in)

hr (in)

a (in)

Effective front unsprung weight without springs, without shocks: (lb)

Front spring weight, one side: (lb)

Front Shock weight, one side: (lb)

Effective rear unsprung weight with springs without shocks: (lb)

Rear spring weight, one side: (lb)

Rear shock weight, one side: (lb)

8013

42384

42367

-1.75

-1.56

.56.1

127

16

2

455

52

1

Note: Unsprung weights include upper (fixed in sprung mass) strut parts. Estimated weight of these parts is between 1 and 2 lbs. No addition should be made to these numbers to account for a portion of the spring.

48

Table 20. Vehicle properties for 1979 Dodge B-200 van.

Weight (lb)

Wheelbase (in)

Wheelbase W8




3808

128

29.48 14.41

Aft of Front Axle Center. a (in) 48.96


Roll. Ixx

Pitch. Iyy

Yaw, Izz


hf (in)

hr (in)

a (in)

Effective fror.t unsprung weight without springs, without shocks: (lb)

Front spring weight. one side: (lb)

Front Shock weight, one side: {lb)


Rear spring weight. one side: (lb}

Rear shock weight. one side:

10923

37474

39633

-1.0

-1.25

49.0

137

17 1/2

2 1/2

464

68

4 lb

Ref.


49

Ref.

Table 21. Vehicle properties for 1982 Chevrolet S-10 pickup.

Weight (lb)

Wheelbase (in)

Wheelbase W8




2717

108

25.0 13.5


Principal Moments of Inertia (in-lb-secz)

Roll, Ixx

Pitch, Iyy

Yaw, Izz


hf (in)

hr (in)

a (in)






Rear shock weight, one side:

3460

17700

20210

0.5

0.5

44.5

115

10

2

360

38

3 lb


50

Ref.

Table 22. Vehicle properties for 1982 Chevrolet C-10 pickup.

Weight (lb)

Wheelbase (in)

Wheelbase W8


Above Ground (in) Above Vehicle Ref •• h (in)


3540

117.5

24.6 11.32



Roll, Ixx 7025

Pitch, Iyy 27760

Yaw, Izz 29580


hf (in) 1.2

hr (in) 1.5

a (in) 48.1

Effective front unsprung weight without springs, without shocks: {lb) 153

Front spring weight, one side: (lb) 15

Front Shock weight, one side: {lb) 2

Effective rear unsprung weight with springs without shocks: (lb) 524

Rear spring weight, one side: (lb) 53

Rear shock weight, one side: (lb) 3


51

Table 23. Vehicle properties for 1982 Ford Fl50 van.

Weight (lb}

Wheelbase (in)

Whee 1 base W8




4170

138

27.8 14.27


Principal Moments of Inertia (in-lb-secz)

Roll, Ixx

Pitch, Iyy

Yaw, Izz


hf (in)

hr (in)

a (in)






Rear shock weight, one side: (lb)

11320

50180

49250

-1.6

-1.3

62'.3

132

14

2

462

47

3

Ref.


52

FULL-SCALE CRASH TEST OF BARRIERS

A tota 1 of 13 full-sea 1 e crash tests were performed. Five were performed on the standard G4 ( 1S) guardrail , and one was performed on a modification of this design. Two tests were performed on a three-cable modified GR1 guardrail and one was performed on a W-beam mounted on wood posts. Four tests were performed on median barriers - one on the improved MB9 and three on a 42-in (107-cm) high concrete median barrier.

Standard G4(1S) Guardrail (Tests 4 through 8)

A cross section of the standard G4(1S) guardrail used in tests 4 through 8 is shown in figure 22. The test installation was 175 ft (53 m) in total length including turned down end treatments on each end. Summaries of the tests performed on this design are presented in table 24 and figures 23 through 27. A modified G4(1S) (shown in figure 28) with a 24-in (61-cm) mounting height and with no blackouts was used in one test with a 4,500-lb (2,043-kg) automobile, and this test is summarized in figure 29.

Two tests with Honda Civ~cs (1,800-lb (817 kg)), one at 15.0 degrees (number 5) and one at 21.5 degree (number 4), were performed on this barrier. No vehicle stability or trajectory problems occurred in either test. In the 15-degree test, redirection was rather smooth and comparatively less damage to the vehicle occurred. Vehicle response was within the limits given in NCHRP Report 230.( 10) In the 20-degree test, a significant amount of wheel snagging and damage to the vehicle occurred.

One test (number 6) was performed on the G4(1S) with a Chevrolet S10 pickup having a test inertia weight of 2,923 lb (1,327 kg) and a gross static weight of 3,260 lb (1,480 kg) with a center-of-gravity height for the empty vehicle (2,717 lb (1,234 kg)) of 25.0 in (63.5 em). The impact conditions were 60.0 mi/h (96.5 km/h) and 22.0 degrees. Stability and trajectory of the vehicle were good. However, the front wheel snagged on a post and was severely damaged.

53

W-Beam Back-up Plate (RE-4-73) Use At Posts Where W-Beam Splice Does Not Occur

5/8" 0 Bolts (F-8-76) ---<

W 6 x 8.5 Posts e 6

1-3" Spacing

5/8" 0 Button Head Bolt (F-3 [1-1/4]-76)

:::1/J==:I//~111 JU:.:::/1/:: 1//E/1 ;: J :.111

12 go. (RE-3-73)

2811

Figure 22. Cross section of G4(1S) guardrail used in tests 4 through 8.

54

0"1 0"1

TEST BARRIER DESIGNATION DESIGN AND DATE

4798-4 G4(1S) 4/6/83

4798-5 G4(1S) 3/31/83

4798-6 G4 ( 1S) 7/12/83

4798-7 G4(1S) 7/27/83

4798-8 G4(1S) 6/28/83

'------- ---- ~

Table 24. Full-scale crash test matrix for G4(1S) guardrail.

TEST VEHICLE TYPE HEIGHT OF COMMENT CONDITIONS TEST INERTIA VEHICLE C.G. lb/mi/h/degree WEIGHT (lb) (in)

2192/59.9/21.5 Honda Civic 20.4 Wheel snagged post. 1856

2100/59.5/15.0 Honda Civic 20.4 Snooth redirection. 1764 Acceptable performace.

3260/60.0/22.0 Chevrolet S10 Pickup 25.0 Vehicle stability and 2923 trajectory good. Wheel I

snagged on post.

4324/59.2/24.0 Dodge 8200 Van 29.5 Vehicle rolled 270 degrees. 3983

4179/56.9/23.5 Ford Fl50 Pickup 26.1 Wheel snagged on post. 3834

(..TJ 0\

0.000 sec 0.071 sec 0.212 sec 0.355 sec

r 'f''''''"E'l''''s.'''' ...,

IT G4(1S) Barrier

>q Test No, .• Date •••• Rail ••••

- ~---[[]--'- - - -ilj. J 21 .so --- 1.0° -........

• 4798-4 • 4/06/83 • G4(1S) Blocked-Out

W-Beam (12 ga)

-........ Impact Speed • • • • Impact Angle . • • • • Exit Speed •••••• Exit Angle • • • • • • Vehicle Acceleration 27 in.

Post Post Spacing . • • • • Length of Installation Rail Deflection

Maximum • • • Permanent .••

Vehicle • • • .

• W6x8.5 Steel • '6.25 ft (1.91 m)

175.0 ft (53.3 m)

1.35 ft (0.41 m) 0.76 ft (0.23 m) 1977 Honda Civic

Vehicle Weight Gross Static •.•.•. 2192 lb (995 kg) Test Inertial ••••• 1R56 lb (843 kg)

Vehicle Damage Classification TAD •••••••••• 01-RFQ-5 SAE •••••••••• 01FREK2

01 RDES2

(Max. 0.050 sec Avg) Longitudinal •••• Lateral •••••• Vertical •••••• Resultant ••••••

Occupant Impact Velocity Longitudinal •• Lateral ••••

Occupant Ridedown Accelerations

Longitudinal .• Lateral ••••

Figure 23. Summary of data for test 4798-4.

59.9 mi/h (96.4 km/h) 21.5 degrees 42.4 mi/h (68.2 km/h) 1.0 degrees

-4.6 g 8.5 g 1.4 g 9.3 g

18.3 fps (5.6 m/s) 18.4 fps (5.6 m/s)

3.6 g 13.0 g

c..n -.....!

0.000 sec

G4(1 S) Barrier

q 0.101 sec 0.203 sec C'.305 sec

= ~~~ ~~ · 2~3!{'~ =tfJ ' ---rt!J_l5' 1 1' I I

---- -Test No. Date •• Rafl ••

Post • • • • Post Spacing • • • • • Length of Installation Rail Deflection

• 4798-5 • 3/31/83 . G4(1S) Blocked-Out

W-Beam (12 ga) • W6x8.5 Steel • 6.25 ft (1.91 m) • 175.0 ft (53.3 m)

• O.R4 ft (0.26 m) • 0.17 ft (0.05 m)

1978 Honda Civic

Maximum •• Permanent ••

Vehicle . . ••• Vehicle Weight

Gross Static •••••• 2100 lb (g53 kg) Test Inertial ••••• 1764 lb (801 kg)

Vehicle Damage Classification TAD . . . • . . . . 01-RFQ-3 SAE . . . • . . 01 FREK1

01RDES2

Impact Speed • Impact Angle • Exit Speed •• Exit Angle • • • •• Vehicle Acceleration

(Max. 0.050 sec Avg) Longitudinal •••• Lateral •••••• Vertical •••••• Resultant ••••••

Occuflant Impact Velocity Longitudinal •• Lateral ••••

Occupant Ridedown Accelerations

Longitudinal •• Lateral ••••



-2.6 g 5.8 g 0.9 9 6.2 g

13.3 fps (4.1 m/s) 18.4 fps (5.6 m/s)

-1.3 g 7.0 9

()1

00

G4( IS) BARRIER

0.000 sec

I

' I~

U. IU/ '"''- u.IOt. !>1:!1.. 0.311 sec

····~ . ''!!JYE'f§f '--- --'-tl[j --- I rfB--~ -- 3.5°

Test No. Date •. Rail .•

Post ..•• Post Spacing . • • • • Length of Installation Rail Deflection

., .

4798-6 7/12/83 G4(1S) Blocked-Out W-Beam ( 12 ga) W6x8.5 Steel 6.25 ft (1.91 m) 175.0 ft (53.3 m)

1.25 ft (0.38 m) 1.96 ft (0.60 m) 1982 Chev. S-10 Truck

Permanent Maximum •••

Vehicle •••••• Vehicle Weight

Test Inertia .•••••• 2923 lb (1327 kg) Gross Static ••••••• 3260 lb (1480 kg)

Vehicle Damage Classification TAD • • • . • • • • • • • 01-RFQ-4 SAE • • • • • • • • • • • 01 FREK3

01RDES2

Impact Speed ••••.•••.• 60.0 mi/h {96.5 km/h) Impact Angle •••••••••• 22.0 degrees Exit Speed ••..••••..• 43.2 mi/h (69.5 km/h) Exit Angle. • . • • • • • • • • 3.5 degrees Vehicle Accelerations

(Max. 0.050 sec Avg) Longitudinal .••• Lateral ••••••. Vertical ...••• Resultant •• ·• • ••

-5.8 g 6.6 g

-1.7 g 7.8 g

Occupant Impact Velocity Longitudinal ••••••• 16.9 fps (5.2 m/s) Lateral •••.•••••• 16.2 fps (4.9 m/s)

Occupant Ridedown Accelerations Longitudinal •••.••• -9.7 g Lateral • • • • • . • • • 9.9 g


(n

\.0

0.000 sec 0.176 sec 0.352 sec 0.631 sec

in.

C: IIIIIJI_li~''~ I ---:3

Vehicle ---subsequently rolled ~24.0°

Post • Post Spacing ••••• Length of Installation

• 4798-7 . 7/27/83 • G4(1S) Blocked-Out

W-Beam (12 ga) • W6x8.5 Steel • 6.25 ft (1.91 m) • 175.0 ft (53.3 m)

............

Impact Speed. . • • • ••• Impact Angle •••••••• Exit •••...•.•••

Vehicle Accelerations

59.2 mi/h (95.3 km/h) 24.0 degrees vehicle subsequently rolled 270 degrees

;,.:'1111 llmam,,.~ Rail Deflection

(Max. 0.050 sec Avg) Longitudinal •••• Lateral ••••••• Vertical •••••• Resultant •••• I •

-4.7 g 5.0 g

-1.7 g 6.3 g

G4( 1 S) Barrier

Permanent •• Maximum •••


1.94 ft (0.59 m) 2.34 ft (0.71 m) 1979 Dodge B200 Van

Test Inertia •.••••• 3983 lb {1808 kg) Gross Static .•••••• 4324 lb (1963 kg)

Vehicle Damage Classification TAD ••••••••••• 01-RFQ-4&L&T-3 SAE . • • • • • • • • • • 01 FREK4

OlRDES3 60TDit03'

Occupant Impact Velocity Longitudinal ••••••• 20.5 fps (6.3 m/s) Lateral •••• I ••••• 16.5 fps (5.0 m/s)

Occupant Ridedown Accelerations Longitudinal •.••• I • -6.1 g Lateral ••••••••• 6.7 g


m 0

o.ooo sec 0.151 sec 0.301 sec 0.502 sec

25.~ lli;], 23.5° ~ I < , < < < < ':if!/' - ' I I ~

• 4798-8 • 6/28/63 • G4(1S) Blocked-Out

W-Beam (12 ga) I II ft Post ••••

uiC:: J), JII&Ju'='JII p t s • . OS pac1ng , , ••• , • W6x8.5 Steel • 6.25 ft (1.91 m)

G4(1S) Barrier

• 175.0 ft (53.3 m) Length of Installation • Rail Deflection

Permanent • · •••• Maximum • • • • • •

Vehicle • • • • • •

• 2.29 ft (0.70 m) • 2.61 ft (0.80 m) .1979 Ford F150 Pickup

Vehicle Weight Test Inertia ••••••• 3834 lb Gross Static ••••••• 4179 lb

Vehicle Damage Classification TAD • • • • • • • • • • • 01-RFQ-5 SAE •••• , •••••• 01 FREK2

01RYES3

(1741 kg) (1897 kg)

Impact Speed. . • • • •• Impact Angle ••••.•• Exit Angle. • • • • • • • Vehicle Accelerations

(Max. 0.050 sec Avg) Longitudinal •••• Lateral ••••••• Vertical •••••• Resultant ••••••

56.9 mi/h (91.6 km/h) 23.5 degrees 25.0 degrees

-5.8 9 4.0 9

-2.5 g 6.0 9

Occupant Impact Velocity Longitudinal ••••••• 27.1 fps (8.3 m/s) Lateral ••••••.••• 14.6 fps (4.5 m/s)

Occupant Ridedown Accelerations Longitudinal •..•••• -10.0 g Lateral •••••••••• 11.6 9


W6x9 Post---

e 12•-611 Spacing

5/811

0 Button Head Bolt

(F-3 [1 1/4] -76)

12 go. (RE-3-73)

2511

7211

4711

Figure 28. Cross section of guardrail used in test 10.

61

"" N

MODIFIED G4(1S) BARRIER

0.000 sec 0.165 sec 0.330 sec 0.492 sec

r , , . . _ * 1 :::=:!:::sa • •; A£:::' • 1 , ,

4~-~ /-C--, J 11: n

Test No. Date •. Rail ••

Post ••••• Post Spacing ••••. Length of Installation Rail Deflection

Permanent • Maximum •.

Vehicle ••.••

'U---1 ~-~0

• 4798-10 Impact Speed. . . . • . • . . 59.5 mi/h (95.7 km/h) • 9/15/83 Impact Angle. . • • • • • . . 15.0 degree . Modified G4(1S) Exit Speed. . • • • • . • . • 48.7 mi/h (78.3 km/h)

W-Beam (12 ga) Exit Angle. . • . • • . . . . 4.0 degree • W6 x 8.5 Steel Vehicle Accelerations • 12.5 ft (3.8 m) (Max. 0.050 sec Avg) • 175.0 ft (53.3 m) longitudinal . . • . . • -2.0 g

Lateral. • . • . • . . • 4.5 g . 2.06 ft (0.63 m) Vertical • • . • • . • • -0.8 g

~ ••• 2.47 ft (0.75 m) Resultant. • . . • . . • 4.9 g . 1979 Chrysler Occupant Impact Velocity .

Newport Longitudinal • • • . . • 11.6 fps (3.5 m/s) Vehicle Weight Lateral •••• , . . . • 12.5 fps (3.8 m/s)

Test Inertia ••••••. 4318 lb (1960 kg) Occupant Ridedown Accelerations Gross Static ••••••• 4644 lb (2108 kg) Longitudinal • . • • . • -1.7 g

Vehicle Damage Classification Lateral. • • • • • • • • 6.8 g TAO ••••••••••• 01-RFQ-3 SAE • • • • • • • • • • • 01 FREKl

01 RDESl


A Dodge B200 van with a center-of-gravity height of 29.5 in (74.9 em) (empty vehicle) was used in test 7. The test conditions were 59.2 mi/h (95.3 km/h) and 24.0 degrees. Gross static weight of the vehicle was 4,324 lb (1,963 kg) and test inertia weight was 3,983 lb (1,808 kg). As the front of the vehicle was being redirected, the left rear wheel began leaving the ground. Both rear wheels and the left front wheel subsequently became airborne as shown in figure 26. After leaving the rail, the vehicle rolled 270 degrees and came to rest on its left side.

A Ford F150 pickup with a center-of-gravity height of 26.1 in (66.3 em) (empty weight 3,863 lb (1,754 kg)) was used in test 8. The test conditions were 23.5 degrees and 56.9 mi/h (91.6 km/h). Gross static weight of the vehicle was 4,179. lb (1,897 kg) and test inertia weight was 3,834 lb (1,741 kg). The vehicle impacted the barrier between posts 6 and 7. The tire passed in front of post 7 leaving tire marks on that post and the rail element. The tire then snagged severely on post 8. The vehicle was redirected and exited the rail at approximately 25 degrees with a maximum ro 11 angle of about 35 degrees. The right front corner of the vehicle was heavily damaged.

Modified G4(1S) Guardrail (Te~t 10)

The· modified G4(1S) guardrail was constructed by omitting the blockout, increasing the post spacing to 12 ft 6 in (3.8 m), and l·owering the rail mounting height to 24 in (61 em). A single test with a 4,500-lb (2,043 kg) automobile (number 10) at 60 mi/h (96.5 km/h) and an impact angle of 15 degrees was performed Gn this guardrail. The purpose of the test was to determine whether this guardrail desiJn would meet the requirements of the Service Level 1 test condition.< 10 Railings of this design exist in some States, and the question was whether the low mounting height would allow the heavy vehicle (4,500 lb (2,043 kg)) to ride over or rollover the railing. There is also a question as to whether snagging might occur with this guardrail, but that was not addressed in this test. This question would be addressed in a test with a small car having a small diameter wheel.

63

The guardrail performed very well in the test reported here. Vehicle response measures including the exit angle were relatively low and the redirection was rather smooth.

W-Beam Rail Mounted 30-in (76-cm) High on Wood Posts (Test 9)

A cross section of this railing design is shown in figure 30. The mounting height of the rail element was 30 in (76 em), and the clear distance below the rail element was 18 in (46 em). An 8-in (20-cm) blackout was used. A single test (summarized in figure 31) with a Honda Civic (1,800 lb (817 kg)) at a 20-degree impact angle was performed on this guardrail to investigate the degree of snagging that might occur. Light to moderate snagging occurred on one post but this was not severe enough to impose excessive accelerations on the vehicle. This was probably due to the fact that the post fractured and, therefore, offered a limited amount of resistance to the vehicle.

Modified GR1 Three-Cable Guardrail (Tests 2 and 11)

A cross section of the three-cable system used in these two tests is shown in figure 32. A 250-ft (76-m) long test installation was constructed.

Tests were performed on this guardrail with a Honda Civic (1800 lb (817 kg)) at 25.5 degrees and a Plymouth {4,500 lb (2043 kg)) at 25.5 degrees. Results of these tests are summarized in table 25 and figures 33 and 34.

Performance of the barrier in the Honda test was found unacceptable because of excessive accelerations imposed on the vehicle and the fact that the vehicle rolled. After initial impact, the barrier deflected allowing the vehicle path to encroach on the area behind the barrier. The rightside tire path was approximately 3.01 ft (0.92 m) behind the barrier about 20 ft (6 m) downstream from impact. At this stage the vehicle was parallel to the barrier. Subsequently, the vehicle began to translate

64

6"x a"x 1'-2" Block (P-11-79)

6" X 8" x 5'-4" Post (P-11-79)

5/8" Cia. Bolt (F-3[18]-76) w/ Washer (F-12-73)

W-Beom, 12 go. (RE- 3 -73)

31"

Figure 30. Cross section of guardrail used in test 9.

65

en en

0.000 sec 0.109 sec 0.272 0.375 sec

Date ••

" §5&. ·,~~~·. ~J : .. o =

......

• 4798-9 Impact Speed. • • • • • 11/1/83 Impact Angle •••••

...... 60.3 mi/h (97 .0 km/h) 19.0 degrees

~test No.

Rail • • 30 in.

• Modified G4(2W) Exit Speed •••••• Blocked-out Exit Angle •••••• W-Beam (12 ga) Vehicle Accelerations

42.6 mi/h(68.5 km/h) 3.8 degrees

Post • • • • • • • • • • 6 x 8 x 64 in wood (Max. 0.050 sec Avg) h>11v;;uJ Post Spacing • • • • • • 6.25 ft (1.91 m) Longitudinal ••••

• 175.0 ft (53.3 m) Lateral ••••••• -5.9 g 6.8 g 2.5 g 9.0 g

Modified G4(2W) Barrier

Length of Installation Rail Deflection



• 0.54 ft (0.16 m) • 1.20 ft (0.37 m) • 1978 Honda Civic

Test Inertia .•••••• 1786 lb Gross Static. • • • • • • 2129 lb

Vehicle Damage Classification TAD ••••••••••• SAE •••••••••••

01RFQ5 01 FREKl OlRDES2

(811 kg) (967 kg)

Vertical •••••• Resultant ••••••

Occupant Impact Velocity Longitudinal • • . • • • 20.6 fps (6.3 m/s) Lateral ••••••••• 20.3 fps (6.2 m/s)

Occupant Ridedown Accelerations Longitudinal •• • • • • • -4.6 g Lateral. • • • • • • • • 9.2 g

Figure 31, Summary of data for test 4798-9.

5-1/2" dia. x 6'-o" -----.. treated wood post

' 5 1/2"

28"

ook Bolts 5/16" ¢

Washer, 12 ga. 3/8

11 l.d.,

1-1/4" o.d.

6'-o"

Figure 32. Cross section of modified GRl, 3 cable guardrail used in tests 2 and 11.

67

0'1 co

TEST DESIGNATION AND DATE

4798-2 l/31/84

4798-11 7/19/83

Table 25. Full-Scale crash test matrix for modified GRl cable guardrail

BARRIER TEST VEHICLE TYPE HEIGHT OF DESIGN CONDITIONS TEST INERTIA VEHICLE C.G.

lb/mi/h/degree WEIGHT (lb) (in)

Modified GR1 2220/59.3/14.5 Honda Civic 20.4 Cable Guardrail 1888

Modified GR1 4585/61.2/25.5 Plymouth Sedan ----Cable Guardrail 4249

COMMENT

I !

Excessive accelerations on vehicle. Vehicle rolled.

Vehicle contained. I Barrier received

I extensive damage.

0.000 sec

0) <~o~~Jt T 1.0

28 in.

0.191 sec 0.382 sec 0.573 sec

. • . • }4._;r-: )!:Jl. ~ Vehicle rolled 90 Jeg . rr:n--- • • • • • •

Test No. Date • Rail •

Post •

Post Spacing •••••• Length of Installation • Rail Deflection

• 4798-2 • 1/31/84 , Modified GR1

Cable Barrier • 5~-ln dia. x 6 ft

wood posts • 12.5 ft (3.a m) . • 250.0 ft (76.2 m)

, , 0.20 ft (0.06 m) • 3.01 ft (0.92 m)

1978 Honda

Permanent •• Maximum , , •


Test Inertia ••••••• 1888 lb (857 kg) Gross Static ••••••• 2220 lb (1008 kg)

Vehicle Damage Classification TAD • • • • • • • • • • • 01R&T5 SAE , , • , , • , , ••• 01FZEK2

01 RDES2 80TDH04

Impact Speed. Impact Angle. Exit ••••

Vehicle Accelerations (Max. 0.050 sec Avg) Longitudinal •••• Lateral •• , • , •• Vertical •••••• Resultant ••••••

Occupant Impact Velocity

59.3 mi/h (95.4 km/h) 14.5 degrees vehicle rolled 90 degrees

-6.2 g 4.5 g

-8.4 g 9.2 g

Longitudinal ••••••• 24.3 fps (7.4 m/s) Lateral •••••••••• 15.5 fps (4.7 m/s)

Occupant Ridedown Accelerations Longitudinal ••••••• 12.8 g Lateral •••••••••• 7.2 g


-.1 0

0.000 sec 0.155 sec 0.310 sec 0.543 sec

~.,:,JI T 28 ~n.

MODIFIED GRl CABLE BARRIER

25.5° ........ ~ [J . • .., '.'"::.::-;._·_~_.__:_...:~ •

Test No. Date Rail

Post

Post Spacing ••••• Length of Installation Rail Deflection



4798-11 7/19/83 Modified GR1 Cable Barrier 5!-in dia.x6ft wood posts 12.5 ft (3.8 m) 250.0 ft (76.2 m)

cables broke 11.42 ft (3.48 m) 1978 Plymouth

'Test Inertia •.••••• 4249 lb Gross Static ••••••• 4585 lb

Vehicle Damage Classification

(1929 kg} (2082 kg)

TAD •.••••••••• 12-FD-4 SAE •••••••.••• 12FDEK2

12RDES3

Impact Speed. Impact Angle. Exit • • • •

Vehicle Accelerations (Max. 0.050 sec Avg)

61.2 mi/h (98.5 km/h) 25.5 degrees vehicle came to rest along centerline of barrier

Longitudinal ••••••• -3.4 g Lateral •••••••••• 2.5 g Vertical. • • • • • • • • -1.3 g Resultant. • • • • • • • • 3.7 g

Occupant Impact Velocity Longitudinal ••••••• 14.2 fps (4.3 m/s) Lateral •••••••••• 11.3 fps (3.4 m/s)

Occupant Ridedown Accelerations Longitudinal ••••••• 7.3 g Lateral ••••••••• -3.5 g


away from the barrier and to yaw back toward the barrier (to the right). A situation was reached where the barrier deflection was negligible but the right front corner of the veh i c 1 e was in contact with at 1 east one cable. The vehicle then contacted a post, spun around to the right and rolled onto its top coming to rest in front of the barrier.

Performance of the barrier in the strength test (test 11) was judged acceptable on the basis that the barrier contained the vehicle; however, the barrier received very extensive damage. Subsequent to initial impact, the barrier deflected a 11 owing the vehi c 1 e path to encroach on the area behind the barrier. The rightside tire path was approximately 11.42 ft (3.48 m) behind the barrier about 40 ft (12 m) downstream from impact. The vehicle came to rest on the centerline of the rail approximately 100 ft downstream of the impact point. The barrier received a massive amount of damage. The concrete anchor upstream of impact was pulled out and the end plates at the first were bent. Eight posts were broken or pulled out of the ground with several being thrown clear of the test site.

Improved MB9 Median Barrier (Test 12)

This barrier design was developed from an improved version of the G9 guardrail which was designed and tested under an earlier FHWA contract.( 19 ) In the earlier project, the guardrail version performed very well in tests with a 32,000-lb (14,529-kg) intercity bus, a 20,000-lb {9,080 kg) school bus, and an 1800-lb (817-kg) automobile.

The key feature of this design is the 14-in (36-cm) blackout with a 40-degree triangular notch cut in the lower end and as shown in figure 35. The wide blackout causes the rail element to rise slightly when the post is deflected laterally. It also provides greater than usual post setback distance to help prevent snagging. The lower end of the outboard flange will bend and allow the rail element to remain nearly vertical during a significant amount of lateral deflection. In the prototype guardrail test in the earlier study, an M14x18 structural shape was used for the blackouts. This shape is no longer readily available, and a W14x22 shape

71

W6x9 Post

5/8" 0 Bolts (F-8-76)

Thrie Beam Back up Plate (RE-63-76) Use at posts where Thrie Beam splice does not occur (12 Gauge)

3511411

6'-91/411

4611

Wl4x22 Spacer Except Terminal

.... :'"-· .. -: :_ .·: .. -:· .: ·,·;!- •.· ...... -: • •,, .4• • • .• • • • o v I o

· ... .. ....

5/8" 0 Button Head Bolt (F-3 [I V4J-76) (No Washer)

Thrie Beam (RE-63-76) (12 Gauge)

.; ·;-.:_; .. : .: .. : ... ··.· .• .. · ... :-: . . . . : · ...

, . . . . . . ·~ ~ .. · .... 7 ••

. .. ..

Figure 35. Cross section of improved MB9 median barrier used in test 12.

72

was substituted in the prototype median barrier tests reported herein.

The median barrier version was developed by simply using the 14-in (36-cm) blackout on both sides of the MB9 system. Mounting height of the rail element was 34 in (86 em).

One test was performed on this barrier with a 40,000-lb (18,160-kg) intercity bus. Subsequent to impact, the front of the bus was contained and redirected. During the initial portion of the collision, the barrier deflected laterally approximately 4.58 ft (1.40 m). During the later part of the collision when the rear of the bus was interacting with the barrier, the rail element on the impacted side of the barrier was severed and additional deflection of the barrier occurred. The rear of the bus then rolled onto the barrier, and the bus came to rest on its left side beyond the test barrier installation. The results of this test are summarized in figure 36.

Damage to the barrier is shown in figure 37. The fracture in the thrie-beam rail element occurred near and downstream of post 13. During deformation of the barrier, the blackout on the impact side folded with the top of the post moving downstream and contacting the rail element. The high loads being imposed on the deformed and distorted barrier structure then caused rupture of the rail element. There were no observed indications that any single structural element in the barrier was excessively weak as compared to the other elements. The loads imposed by the test vehicle were simply so high and the resulting deformations and distortion of the barrier were so large that fracture of the rail element occurred.

Modifications to the barrier to improve performance at this level of test severity may require that the entire structure be stiffened and made stronger. However, some improvement in performance may be achieved by simply using a 10-gauge thrie-beam rail element to replace the 12-gauge element.

73

-...! ..J::>

0.000 sec

IMPROVED MB9 MEDIAN BARRIER

0.198 sec 0.497 sec

• 4798-12 Vehicle •••• • 12/15/83 Vehicle Weight • Improved MB9 Test Inertia.

Blocked-out Gross Static. Thrie-Beam (12 ga) Impact Speed ••

Post •••• , ••••• W6x9 steel Impact Angle ••.•• Post Spacing •••••• 6.25 ft (1.91 m) Vehicle Accelerations Length of Installation • 175.0 ft (53.3 m) (Max. 0.050 sec Avg) Rail Deflection Longitudinal.

Impact Side Lateral •••••• Permanent ••••• Rail broke Vertical •••••• Maximum •••••• 4.58 ft (1.40 m) Resultant • • •••

Rear Rail

0. 700 sec

1954 GMC Scenicruiser

2M,140 lb (12,776 kg.) 39,970 lb (18,146 ka) 59.6 mi/h (95.9 km/h} 14.5 degrees

-1.1 g -4.5 g -1.8 g 4.5 g

Permanent ••• • • 1.76 ft (0.54 m) Maximum •••••• 2.22 ft (0.68 m)

Bus subsequently rolled onto its side.


Figure 37. Details of rail separation.

75

42-in (107-cm) High Concrete Median Barrier (Test 1, 3, and 13)

A cross section of the 42-in (107-cm) high concrete median barrier is shown in figure 38. Slopes on the faces of this barrier are the same as the New Jersey safety shape. The upper face was extended to 32 in (81 em), and asphaltic concrete was placed against the lower 3-in (8-cm) vertical face. The barrier was 12 in (30 em) thick at the top. The barrier was cast-in-place on compacted subgrade, and hot mix asphaltic concrete pavement was installed adjacent to the barrier on the impact side to simulate a roadway cross section as shown in figure 39. A 3-in thick layer of asphalt was placed behind the barrier to provide lateral support to the barrier as would be provided by the roadway cross section on that side.

This barrier, installed on a different simulated roadway section, had been studied earlier by the New Jersey Turnpike Authority.( 20) Performance achieved with the shoulder and median cross slope used in that work was not suitable. The Turnpike Authority then sponsored some analytical work using computer simulations of impacts and the cross section used in the tests reported herein was based on the results of those simulations. The Turnpike Authority also participated in tests of the barrier reported herein. A series of three tests, listed in table 26 and summarized in figures 40 through 42, was performed on this barrier. The tests included a Honda automobile (2,118 lb) impacting at 59.9 mi/h and 14.5 degrees, a Plymouth sedan (4,880 lb) impacting at 58.6 mi/h and 16.5 degrees and an 80,180-lb tractor-trailer impacting at 52 mi/h and 15 degrees. The trailer was a van and was loaded with bags of sand. The bags of sand were placed uniformly over the floor of the trailer and were restrained with a plywood covering bolted to the floor of the trailer. Height to the center-of-gravity of the sand was approximately 67 in (163 em).

Acceptable performance of the barrier, in accordance with NCHRP Report 230 criteria, was demonstrated in all three tests.(lO)

76

12" :l 3 3/811

211 Cl.

t 0 0 #6 Bars e 12

11 c-c 611

IMPACT ~ 0 8-#6 Bars

SIDE Longitudinal OF 611

Steel BARRIER

~ 0

32 11

1411

L 711

0 0

32 3/411 ______ ..,.,3.

Asphaltic Concrete

Figure 38. Cross section of 42-in high concrete safety shape used in tests 1, 3, and 13.

77

""-1 co

Traffic Lane Shoulder Median

12'-o" 5'-o" a'-o" a'-o"

IMPACT r f SIDE OF 5 5/8" H.M.A.C. BARRIER

I 3'-6" II

1% Slope 5% Slo~e 3" (3 H.M.A.C.

_I_ I IIIII v IIIII

' 6" 11'-4" ~

Compacted Crushed Limestone Base _)

I

H.M.A.C. - Hot Mix Asphaltic Concrete Special Subgrade Material - Red sandy clay

subgrade material with a maximum dry density (AASHTO Tl80) of 126.0 lb/ft3

4'-o"

Figure 39. Cross section of test barrier installation including simulated portions of hi,ghway cross section.

4'-o"

Material

e

-.....! ~

TEST BARRIER DESIGNATION DESIGN AND DATE

4798-1 42-in high 4/20/83 Cone. Med. Bar.



* Reference 1

Table 26. Full-scale crash test matrix for 42-4n high concrete median barrier.

TEST VEHICLE TYPE HEIGHT OF CONDITIONS TEST INERTIA VEHICLE C.G. lb/mi/h/degree WEIGHT (lb) (in)

2118/59.9/14.5 Honda Civic 20.4* 1783

4880/58.6/16.5 Plymouth Sedan ----** 4520

80,180/52/15 International ----*** COE Tractor Van Trailer 29,600

COMMENT

Acceptable performance



** Height of e.G. not measured. Approximate height was 21 in. ***Height of C.G. not measured. Approximate height of C.G. of ballast in trailer was 67 in.

Approximate height of C.G. of trailer and ballast was 64 in.

I

00 0

0.000 sec 0.053 sec

Continuous Mod. Safety Shape

Test No. Date •• Rail ••

Length of Installation Rail Deflection


Vehicle ••••••

• 4798-1 • 4/20/83 • Continous Mod.

Safety Shape • 250 ft (76 m)

• 0 ft (O m) • 0 ft (0 m)

1977 Honda Civic Vehicle Weight

Test Inertia ••••••• 1783 lb (809 kg) Gross Static. • • • • • • 2118 lb (962 kg)

Vehicle Damage Classification TAD ••••••••••• 11-LFQ-3 SAE • • • • • • • • • • • 11 FLEKl

11LDES2

0.158 sec

Impact Speed. Impact Angle. Exit Speed •• Exit Angle ••••• Vehicle Accelerations

(Nax. 0.050 sec Avg) Longitudinal .••• Lateral ••••••• Vertica1 .••••• Resultant ••••••

0.264 sec

59.9 mi/h (96.4 km/h) 14.!) deqrees 55.3 mi/h {89.0 km/h) 2.5 degrees

-4.6 g -10.0 g

3.0 g 11.3 g

Occupant Impact Velocity Longitudinal • . • • • . 12.5 fps (3.8 m/s) Lateral. • • • • • • • • 19.7 fps (6.0 m/s)

Occupant Ridedown Accelerations Longitudinal •••••• -1.0 g Lateral •••••.••• -13.9 g


(X) ......

0.000 sec v.v:~l:l St!l. • u.J!Ib sec 0.295 sec

Continuous 14od. Safety Shape

16. 50 ! r::::::-n~-:-=~~= ------- -~ 'E3f= I 5. ocr


Length of ln5tallation Rail Deflection


Vehicle .••••• Vehicle Weight

• 4798-3 • 5/24/133 • Continuous Mod.

Safety Shape • 250 ft (76 m)

• 0 ft (U m) • 0 ft (U m) • 1977 Plymouth

Impact Speed. Impact Angle.

. Exit Speed •• Exit Angle •••••• Vehicle Accelerations

(~lax. 0.050 sec Avg) Longitudinal •••• Lateral ••••••• Vertical •••••• Resultant. • ••••


-4.2 g -7.9 g

Test Inertia. • • • • • • 4520 lb Gross Static ••••••• 4880 1~

1.8 g 8.6 g

;2052 kg) Occupant Impact Velocity (2216 kg) Longitudinal • • • • • • 10.4 fps (3.2 m/s)

Vehicle Damage Classification TAD ••••••••••• SAE ••••••••••..•

11-LF(J-4 11 FLEK2 11LDES2

Lateral. •••••••• 18.2 fps (5.6 m/s) Occupant Ridedown Accelerations

Longitudinal • • • • • • -2.4 g Lateral ••••••••• -7.0 g


(X) N

0.000

Continuous Mod. Safety Shape

0.202 0.403 0.820

16.5 ( ~ L...J[.I t;;:=;;IQI ._..__,. r--w-, ~ ~~ '-----1"U


Length of Installation • Rail Deflection

Permanent • • Maximum •••

Vehicle. . • ••• Vehicle Weight

Empty Weight. Gross Static.

• 4798-13 • 5/26/83 • Continuous Mod.

Safety Shape 250 ft (76 m)

• 0 ft (0 m) • 0 ft (0 m) • Tractor/Trailer

• 29,600 lb (13,438 kg) • 80,180 lb (36,402 kg)

Impact Speed. • • • • • • • • 52.1 mi/h (83.8 km/h) Impact Angle. • • • • • • • • 16.5 degrees Tractor Accelerations at Drive Axles

(Max. 0.050 sec Avg) Longitudinal ••• Lateral •••••• Vertical ••••• Resultant •••••

trailer Max. Roll ~ngle

-6.5 g -3.1 g -9.3 g 11.1 g 52 degrees


EMBANKMENT TRAVERSAL TESTS

Three full-scale embankment traversal tests were performed (table 27). Vehicles used were a 1979 Ford F150 pickup, a 1979 3/4-ton Dodge van, and a 1979 Honda Civic automobile. These tests and the results are discussed in the following paragraphs. Results of the tests are summarized in table 27 and detailed information is presented in appendix C.

The test site was on a two-lane highway with paved shoulders. A partial cross section of the fill embankment in the middle portion of the test site, plotted from field measurements, is shown in figure 43. The main portion of the side slope has a 3 to 1 slope (nominal) and the height of the embankment is approximately 15 feet (4.6 m). Native grasses and weeds were growing on the embankment and were cut prior to testing.

During a test, the vehicle was driven along the left lane toward the test site and was accelerated to test speed. At a predetermined location, a right turn steer input was initiated such that the vehicle would exit the shoulder and enter the embankment slope on a path making a 15-degree angle with the centerline of the roadway. After the vehicle was established on a path down the embankment, a left steer was input to attempt to return to the roadway.

In test 14, a 1979 Ford F150 pickup (test inertia mass of 4450 lb (2020 kg)) equipped with remote guidance system was directed toward the test site at 50 mi/h. As a time reference, the first steering input (to the right) was considered as time zero.

Approximately 1.4 seconds after the right steer input, the vehicle 1 eft the edge of the roadway at 15 degrees. A 1 eft steer input was initiated at about 2.6 seconds, but the front wheels began to sideslip, and the vehicle continued down the embankment slowly responding to the steer input. After reaching a maximum of 50.8 ft (15.5 m) away from the edge of the shoulder (at about 3.9 seconds), the vehicle began its ascent

83

Table 27. Full-scale embankment traversal tests.

TEST TEST COMMENTS DESIGNATION CONDITIONS AND DATE lb/mi/h/degrees

4798-14 4450/50/15 Vehicle stable. Maximum 9/20/84 Ford F150 Pickup roll approx. 23 degrees.

4798-15 4120/50/15 Vehicle stable. Maximum 10/4/84 Dodge Van roll approx. 23 degrees.

4798-16 1938/50/15 Vehicle rolled over 360 4/25/85 Honda Civic degrees.

84

-DISTANCE FROM SHOULDER EDGE (FT)

0 I 0 20 30 40 50 60 70 80 90 1--u. 0 ~~------------~--_.--------~----J: 10 1--Q. UJ 20 0

CROSS SECTION OF SLOPE

Figure 43. Cross section of embankment used for testing.

85

up the embankment. The vehicle returned to the roadway at approximately 8.2 seconds about 320 ft (98 m) downstream of the point where it left the roadway.

The vehicle remained stable during the entire test period with a maximum roll angle of 23 degrees. There was no damage to the vehicle.

In test 15, a 1979 Dodge 3/4-ton van (test inertia mass of 4120 lb (1870 kg)) equipped with a remote guidance system was directed toward the test site at 50 mi/h. For time reference, the right steer input was chosen as time zero.

Approximately 2.0 seconds after steer input the vehicle left the edge of the roadway at 15 degrees. At 2.8 seconds the left steer was input. The right front wheel dug into the ground, and the vehicle began redirecting very slowly. The vehicle path (left tire path) reached a maximum of 36.8 ft (11.2 m) away from the edge of the shoulder. Shortly thereafter (5.6 seconds), a hard left steer was input. The vehicle then made a quick ascent up the embankment, and at 12 seconds it returned to the roadway 343 ft (105 m) downstream of the point where it left the road.

The vehicle•s behavior was sta~le throughout the test. Maximum roll was about 23 degrees. There was no damage to the vehicle.

In test 16, a 1979 Honda (test inertia mass of 1938 lb (880 kg)) equipped with a remote guidance system was directed toward the test site at 50 mi/h. As a time reference, the right steer input was used as time zero.

Approximately 1.2 seconds after the right steer input the vehicle left the edge of the· roadway at 15 degrees. Left steer was initiated at about 2.1 seconds and shortly thereafter the rear of the vehicle began to slide around (vehicle yawed counterclockwise). As the vehicle slid toward the bottom of the embankment the tires on the right side began to plow into the ground. At 3.6 seconds the left front wheel left the ground and

86

the vehicle began to roll to the right. The vehicle rolled one revolution and came to rest upright in the bottom of the ditch, 215 ft (86 m) downstream of the point where it left the roadway.

On the basis of these limited test results and available simulation work, it appears that smooth, well compacted roadside slopes as steep as 3 to 1 can be traversed safely; however, vehicle stability on such a slope is very vulnerable and small discontinuities in the terrain may upset the vehicle.

87

COMPUTER SIMULATIONS

Two types of full-scale tests-embankment traversals and longitudinal barrier impacts were simulated with computer programs.

Embankment Traversal Simulations

The purpose of this task was to determine those roadside embankments which cannot be safely traversed by minisize vehicles and high center-of-gravity specialty vehicles. Three roadside embankments, three vehicles, two encroachment angles, and two driver responses were selected for the simulation matrix as shown in table 28. Driver responses were assumed to begin 1.5 sec after the vehicle left the roadway. Figure 44 shows the roadside terrain which was simulated. Note that the coefficient of rriction was assumed to be 0.5 for the entire roadside.

The contract statement of work required that HVOSM computer program be used for simulating vehicles traversing embankment slopes. Several versions of this computer program exist. Two recently developed versions are HVOSM-VD2 and HVOSM-RD2. The VD2 version has a more complex vehicle model including driver response simulation and additional degrees of freedom for tire spin. The RD2 version is intended for safety appurtenance roadway design and more heavily emphasizes barrier impacts. A third version of this program is the TTl version designated HVOSM-TTI. During the course of this task, all three versions were used.

Much of the important vehicle data required by HVOSM was measured by the University of Michigan Transportation Research Institute. (1,2) The remaining input data was either measured by TTl or estimated from measurements made from similar vehicles.

When simulation of the Honda Civic was attempted with HVOSM-VD2, errors in the independent rear suspension modeling routines were uncovered. The errors caused the spring suspension forces and deflection to be grossly in error. When the Honda was modeled as a solid rear axle

88

EMBANKMENT SLOPE

VEHICLE

ENCROACHMENT ANGLE

DRIVER RESPONSE

Table 28. Simulation matrix variables.

3:1, 4:1, 6:1

1978 Honda Civic, 1979 Ford F-150 Pickup, 1979 3/4-Ton Dodge Van

15 degrees, 25 degrees

Full Braking, 8 degrees Steerback

89

UJ z a: c:( UJ .J 0 .J .... :)

X 0 (!) X -a: C/)

~ ROADWAY

I I

PLAN

.... z UJ 2 ~ z c:( m 2 L&J

ENCROACHMENT ANGLE (15°, 25°)

SLOPE

COEFFICIENT OF FRICTION : 0.5 (ALL SURFACES)

~VARIABLE SLOPE (6:1, 4:1, 3:1)

5001

CROSS SECTION

Figure 44. Drawing of embankment used in simulations.

90

vehicle using HVOSM-VD2 errors were not encountered. Several engineers in the development and use of this computer program were contacted concerning these errors and none had used HVOSM-VD2 to model a vehicle with independent rear suspension.

The results of simulations of the three vehicles with HVOSM-VD2 are shown in table 29. As shown in the table, the simulations predicted that all three vehicles studied would be stable on slopes as steep as 3:1. It was therefore decided to model the Honda as having a solid rear axle and rerun the simulations with TTl's version of HVOSM; and, as shown in table 29, no significant differences were found between the two models.

Finally, HVOSM-RD2 was employed to model the Honda as having independent rear suspension to determine if the suspension model influenced vehicle stability. The problems associated with HVOSM-VD2 simulations of an independent rear suspension were not encountered. As shown in table 29, results from HVOSM-RD2 predicted no rollovers for the roadside terrain configurations simulated, and the predicted maximum roll angles correlate well with simulation results from the other versions of HVOSM.

Vehicle rollover was not predicted in any of the embankment simulations conducted. Maximum roll angles for each simulation are shown in table 29. Note that the maximum roll angle predicted was only 28 degrees. Based on the findings shown in tab 1 e 29 and those reported in reference 21, it can be concluded that minisize and specialty vehicles are not particularly unstable on smooth, well compacted roadside slopes of 3:1 or less. Additional research should be conducted to study the effects of ditch bottom configuration on the stability of the vehicles considered herein.

Longitudinal Barrier Impact Simulations

The W-beam barrier crash tests discussed in the previous sections have established barrier performance for five different vehicles under a

91

.\.0 N

Computer Code

HVOSM-VD2

HVOSM-R02

HVOSM-TTl

Side Slope

.Encroachment Angle

Driver Inputs

1978 Honda Civic

1979 Ford Fl50 1/2-Ton PU

1979 Dodge Van 3/4-Ton

1978 Honda Civic

1978 Honda Civic

- -

Table 29. Maximum roll angle HVOSM computer simulations.

3:1 4:1

15 degrees 25 degrees 15 degrees 25 degrees

Steer Full Steer Full Steer Full Steer Full Back Braking Back Braking Back Braking Back Braking

28 28 28 28 18 28 20 20

25 25 25 25 -- -- -- --26 -- 22 -- 19 -- 17 17

28 28 28 28 18 -- 20 --'

28 -- 28 -- 18 -- 22 ---- - -- ----- ---~ ---

6:1

15 degrees 25 degrees

Steer Full Steer Full Back Braking Back Braking

12 -- 12 --

-- -- -- ---- -- -- --

-- -- -- --I

13 -- 13 --I

total of seven impact conditions. In these tests, four vehicles exhibited a tendency to snag on guardrail posts, while the fifth rolled over after impacting a W-beam barrier. It is desirable to determine the limiting impact conditions that preclude either wheel snag or rollover for each veh i c 1 e. The GUARD computer program is currently the only gua rdra i 1 accident simulation model that can predict wheel snagging and vehicle rollover. Therefore, it was decided to use the GUARD program to establish the limits of performance of W-beam guardrail.

The first phase of the simulation effort involved validation of GUARD version 1.1 for use with minisize automobiles and utility vehicles. The validation effort consisted of simulating seven crash tests and comparing simulation results with crash test results. Thereafter, 35 additional simulations were conducted to more precisely determine the limit of performance of blocked out W-beam barrier. A detailed description of the guardrail impact simulation effort can be found in appendix D.

The GUARD simulation gave good predictions of W-beam guardrail performance when impacted by utility and minisize vehicles. Further, the program gave reasonably good predictions of wheel snagging and vehicle rollover, and it was therefore concluded that GUARD could be used to more precisely define the impact conditions under which these problems first arose.

Performance limits for the G4(1S) barrier were established by simulating impacts with four different types of vehicles for several impact speeds and angles. The vehicle classes studied included minisize vehicle, small pickup, full-size pickup, and full-size van. Minisize vehicles, small pickups, and full-size pickups have exhibited a tendency to snag on guardrail posts during crash testing. Therefore, wheel snag was selected as the primary measure of barrier performance for these vehicles. (Note that the point of impact for these simulations was selected to maximize the likelihood of wheel snagging.) The full-size van crash test conducted under this study has shown that vans may roll over when striking the G4(1S) barrier. Vehicle roll stability was selected as

93

the primary measure of barrier performance for full-size van simulations. Program stability problems were encountered during simulation of van collisions at speeds between 45 and 55 mi/h. These problems could not be resolved, and G4(1S) performance limits with full-size vans could not be precisely determined.

The modified G4(1W) from test 9, shown in figure 30, was studied to determine its performance 1 i mit with minis i ze veh i c 1 es. Barrier performance was determined for both 15- and 20-degree impact angles. Wheel snag was again selected as the primary measure of barrier performance. Table 30 shows the results of the GUARD simulations made to better determine the performance limits of the G4(1S) barrier and a modified G4(1W) barrier.

9.4

Table 30. Simulation results used to establish barrier performance limits.

Impact Impact Minisize Vehiclea Angle (degrees)

Speed (mi/h) G4(1S)

15 50 No Wheel Snag

15 55 Wheel Snag

15 60 Wheel Snag

20 40 No Wheel Snag

20 45 Wheel Snag

20 50 Wheel Snag

20 60 Wheel Snag

25 40 --25 45 --25 50 --25 55 --25 60 --

a 1978 Honda Civic b 1982 Chevrolet S-10 c 1979 Ford F150 d 1979 Dodge B-200 -- Not Simulated * Premature Termination

Modified G4(1W)

--

--No Wheel Snag

No Wheel Snag

No Wheel Snag

Wheel Snag

Wheel Snag

----------

Small Pickupb Fullsize Pickupc Fullsize Vand G4( 1S) Barrier G4(1S) Barrier G4(1S) Barrier

No Wheel Snag No Wheel Snag --

-- -- --Wheel Snag Wheel Snag No Rollover

No Wheel Snag No Wheel Snag --

-- -- --Wheel Snag Wheel Snag --Wheel Snag Wheel Snag --

No Wheel Snag Wheel Snag No Rollover

Wheel Snag Wheel Snag * Wheel Snag Wheel Snag *

-- -- *

-- -- Rollover

95

SUMMARY AND CONCLUSIONS

Longitudinal traffic barriers, including several guardrail designs and two median barriers, were studied. Computer simulations of vehicle barrier impacts and full-scale crash tests were performed. Computer simulations and full-scale tests of vehicles traversing embankments were also performed.

42-in High Concrete Safety Shape

One of the median barriers studied was a 42-in high concrete safety shape. This barrier, installed on a simulated roadway section, had been studied earlier by the New Jersey Turnptke Authority. (20) Performance achieved with the shoulder and median cross slope used in that work was not acceptab 1 e. The roadway section was modified, and three full-seale crash tests were performed in the study reported herein. Impact conditions for the three tests were 2,118 lb/59.9 mi/h/14.5 degrees, 4,880 lb/58.6 mi/h/16.5 degrees and 80,180 lb/52 mi/h/15 degrees. Acceptable performance by NCHRP Report 230 criteria was obtained in all tests. (lO) The 80,000-lb vehicle was a van type tractor-trailer. The trailer was ballasted with bags of sand placed on the floor. Height to the center-of-gravity of the bags of sand was approximately 67 in (163 em).

Following the successful testing of thi~ barrier, the New Jersey Turnpike Authority has constructed approximately 6 ·miles of this barrier using a slipforming operation.

G4(1S) Guardrail

Several full-scale crash tests were performed on the G4(1S) guardrail design with vehicles ranging from an 1800-lb (817 kg) Honda automobile with a center-of-gravity height of 20.3 in (51.6 em) to a 4,300-lb (1,952-kg} van with a center-of-gravity height of 29.5 in (74.9 em). These tests and computer simulations of vehicle impacts with the G4(1S) guardrail were performed to establish performance limits of the guardrail. Impact conditions for tests performed on this barrier were

96

1,800 lb/60 mi/h/20 degrees, 1,800 lb/60 mi/h/15 degrees, 2,900 lb/60 mi/h/22 degrees, 3,980 lb/60 mi/h/25 degrees and 3,830 lb/60 mi/h/25 degrees. Results from these tests were used to calibrate and validate the GUARD computer program. The program gives good predictions of gross vehicle motions, wheel position relative to the guardrail, and barrier damage. However, the simulation model predicts excessively high peak vehicle accelerations and vehicle damage. Although the program is frequently unstable and difficult to use, when these problems are overcome the model can be a valuable tool in the design and evaluation of guardrail systems.

Simulations of impacts . at various impact conditions were then performed to predict the limiting conditions below which wheel snagging and rollover would not occur. These limiting conditions are shown in table 31.

Table 31. G4(1S) maximum impact-speeds to preclude wheel snag and rollover.

Vehicle Im~act Angle (desrees) Classification 15 2

Mini-Size Auto* 50 mi/h 40 mi/h

Small Pickup* 50 mi/h 40 mi/h

25

-40 mi/h

Full-Size Pickup* 50 mi/h 40 mi/h <40 mi/h

Full-Size Van**

* Limited by wheel snagging. **Limited by vehicle rollover.

60 mi/h - 45 mi/h

Limiting impact conditions to preclude minivehicle wheel snag on a 30-in high G4(1W) barrier have been established. For impact angles of 15 and 20 degrees, wheel snag will not occur at speeds less than 60 and 45 mi/h, respectively.

97

For strong-post, W-beam guardrails, the point of impact can greatly influence the probability and degree of wheel snag.

Improved MB9 Median Barrier

One full-scale crash test was performed on this barrier with a 40,000-lb intercity bus traveling at 59.6 mi/h and impacting at a 14.5-degree angle. The barrier did not demonstrate suitable performance in this test. Subsequent to initial impact, the front of the bus was contained and redirected. During the later part of the collision when the rear of the bus was interacting with the barrier, the rail element on the impacted side of the barrier was severed and additional deflection of the barrier occurred. The rear of the bus then rolled onto the barrier, and the bus came to rest on its left side beyond the test barrier installation.

Embankment Traversals

The behavior of vehicles traversing embankments was studied through full-scale tests and computer simulations. Minisize and speciality vehicles were emphasized in this task to enhance available information on severity of embankment slope traversals. In the simulations, embankment slopes of 3 to 1, 4 to 1 and 6 to 1 were studied. Encroachment angles of 15 and 25 degrees were used. Driver inputs included steer-back or full braking.

In many situations, sideslip of the vehicle was predicted and in the more severe conditions, spinout was predicted. Rollovers were not predicted for even the most severe conditions.

Reasonable agreement between the simulations and full-scale tests was found.

Full-scale tests were performed with a pickup, van, and minisize automobile. The pickup and van traversed a 3 to 1 slope without rolling

98

over although significant sideslip occurred. The minisize automobile (Honda Civic) traveled down the slope far enough to encounter the ditch and rolled 360 degrees in the ditch.

It appears that smooth, well compacted roadside slopes as steep as 3 to 1 can be traversed safely; however, vehicle stability on such a slope is very vulnerable and small discontinuities in the terrain may upset the vehicle.

99

REFERENCES

(1) C. B. Winkler, 11 Evaluation of Barrier Limit Capacity for Different Classes of Vehicles and Impact Conditions, 11 University of Michigan Transportation Research Institute, Ann Arbor, ~ichigan, May 1983.

(2) C. B. Winkler, 11 Evaluation of Barrier Limit Capacity for Different Classes of Vehicles and Impact Conditions, 11 University of Michigan Transportation Research Institute, Ann Arbor, Michigan, August 1983.

(3) R. D. Ervin et al., 11 The Yaw Stability of Tractor-Semitrailers During Cornering... Appendices, Final Report Contract DOT-HS-7-01602, June 1979.

( 4) Southwest Research Institute, 11 Bri dge Rail Retrofit For Curved Structures, .. Draft Report for FHWA/RD, June 1981.

(5) Sol Davis, 11 Determination of Inertia, Suspension Geometric and Stiffness Properties of Vehicles for Use in the Analytical Evaluation of Highway Appurtenances, .. Dynamic Science, Inc., June 1982.

(6) Carroll Thatcher, 11 Mobile Parametric Measurement Device, Volume 1: Operation, .. Final Report on Contract DOT-HS-6-01413, January 1980.

(7) Southwest Research Institute, 11 Bridge Rail Refrofit for Curved Structures, Vol. 2, 11 Draft Report for FHWA, June 1981.

(8) R. E. Stirley of The Motor Industry Research Association to D. L. Ivey of The Texas Transportation Institute, Private Communication, 12/13/76.

{9) TTl Research, Report 140-1, 11 Documentation of Input For Single Vehicle Accident Computer Program, for Texas Highway Dept., July 1969.

( 10) Jarvis D. Michie, "Recommended Procedures For The Safety Performance Evaluation of Highway Appurtenances, .. NCHRP Report 230, March 1981.

(11) Christopher B. Winkler, 11 Inertial Properties of Commercial Vehicles, .. HSRI, April 1981.

(12) Ron Leford of GM Proving Grounds Vehicle Dynamics Lab to Mike Love, TTl. Private Communication, 6/17/82.

(13) Sol Davis, 11 Determination of Inertia, Suspension, geometric and Stiffness Properties of Vehicles For Use in The Analytical Evaluation of Highway Appurtenances, .. Dynamic Science, Inc., June 1982.

{14) MGA Research Corp., 11 An Analytical Study of Electric Vehicle Handling Dynamics: Appendix A; 11 NASA Report NASA-CR-162870, May 1979.

100

REFERENCES (continued)

(15) Effects of Tire Properties on Truck and Bu~ Handling, Vol. 1; Final Report for NHTSA, Contract DOT-HS-4-00943, December 1976.

(16) R. D. Ervin, et al, "The Yaw Stability of Tractor-Semitrailers During Cornering." Appendices, Final Report Contract DOT-HS-7-01602, June 1979.

(17) G. L. Basso, "Functional Derivation of Vehicle Parameters For Dynamic Studies," National Research Counctil Canaga Report LTR-ST. 747, September 1974.

(18) Sol Davis, "Test and Evaluation of Heavy Vehicle Barrier Concepts -Technical Report," Dynamic Science, Inc., Contract DOT-FH-11-9115, July 1981.

(19) D. L. Ivey, "Test and Evaluation of W-Beam and Thrie-Beam Guardrails," Final Report on Contract DOT-FH-11-9485, Texas Transportation Institute, Texas A&M University System, College Station, Texas, June 1982.

(20) C. E. Buth et al., "Development of a High-Performance Median Barrier," Final Report, Contract DOT-FH-11-9485, Texas Transportation Institute, College Station, Texas, April 1983.

(21) G. Weaver, E. L. Marquis, and R. M. Olson, "Selection of Safe Roadside Cross Sections," NCHRP Report 158, Transportation Research Board, Washington, D.C., 1975.

101

FEDERALLY COORDINATED PROGRAM (FCP) OF HIGHWAY RESEARCH, DEVELOPMENT, AND TECHNOLOGY

The Offices of Research, Development, and Technology (RD&T) of the Federal Highway Administration (FHW A) are responsible for a broad research, development, and technology transfer program. This program is accomplished using numerous methods of funding and management. The efforts include work done in-house by RD&T staff, contracts using administrative funds, and a Federal-aid program conducted by or through State highway or transportation agencies, which include the Highway Planning and Research (HP&R) program, the National Cooperative Highway Research Program (NCHRP) managed by the transportation Research Board, and the one-half of one percent training program conducted by the National Highway Institute. The FCP is a carefully selected group of projects, separated into broad categories, formulated to use research, development, and technology transfer resources to obtain solutions to urgent national highway problems.

The diagonal double stripe on the cover of this report represents a highway. It is color-coded to identify the FCP category to which the report's subject pertains. A red stripe indicates category 1, dark blue for category 2, light blue for category 3, brown for category 4, gray for category 5, and green for category 9.

FCP Category Descriptions

1. Highway Design and Operation for Safety Safety RD&T addresses problems .associated with the responsibilities of the FHW A under the Highway Safety Act. It includes investigation of appropriate design standards, roadside hardware, traffic control devices, and collection or analysis of physical and scientific data for the formulation of improved safety regulations to better protect all motorists, bicycles, and pedestrians.

2. Traffic Control and Management Traffic RD&T is concerned with increasing the operational efficiency of existing highways by advancing technology and balancing the demand-capacity relationship through traffic management techniques such as bus and carpool preferential treatment, coordinated signal timing, motorist information, and rerouting of traffic.

3 • Highway Operations This category addresses preserving the Nation's highways, natural resources, and community attributes. It includes activities in physical

maintenance, traffic services for maintenance zoning, management of human resources and equipment, and identification of highway elements that affect the quality of the human environment. The goals of projects within this category are to maximize operational efficiency and safety to the traveling public while conserving resources and reducing adverse highway and traffic impacts through protections and enhancement of environmental features.

4. Pavement Design, Construction, and Management Pavement RD&T is concerned with pavement design and rehabilititation methods and procedures, construction technology, recycled highway materials, improved pavement binders, and improved pavement management. The goals will emphasize improvements to highway performance over the network's life cycle, thus extending maintenance-free operation and maximizing benefits. Specific areas of effort will include material characterizations, pavement damage predictions, methods to minimize local pavement defects, quality control specifications, long-term pavement monitoring, and life cycle cost analyses.

5. Structural Design and Hydraulics Structural RD&T is concerned with furthering the latest technological advances in structural and hydraulic designs, fabrication processes, and construction techniques to provide safe, efficient highway structures at reasonable costs. This category deals with bridge superstructures, earth structures, foundations, culverts, river mechanics, and hydraulics. In addition, it includes material aspects of structures (metal and concrete) along with their protection from corrosive or degrading environments.

9. RD&T Management and Coordination Activities in this category include fundamental work for new concepts and system characterization before the investigation reaches a point where it is incorporated within other categories of the FCP. Concepts on the feasibility of new technology for highway safety are included in this category. RD&T reports not within other FCP projects will be published as Category 9 projects.

HRD-11/7-86(200)QE

Documents

Volume I : Summary Report€¦ · Volume I : Summary Report Research, Development. and Technology Turner-Fairbank Highway Research Center 6300 Georgetown Pike Mclean, Virginia 22101