Manual for Assessing Safety Hardware

Transcription

1 American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware 2009

2 vii PREFACE Effective traffic barrier systems, end treatments, crash cushions, breakaway devices, truck-mounted attenuators, and other hardware are used to achieve the highest levels of highway safety. New systems are continually emerging to address safety problems, and traditional devices and practices for their use are being improved in response to an increased understanding of safety performance, a changing vehicle fleet, the emergence of new materials, and other factors. Full-scale crash testing has been and will continue to be the most common method of evaluating the impact performance of safety hardware. Because many agencies conduct such tests, there is a need for uniformity in the procedures and criteria used to evaluate traffic barriers and other roadside safety features. Procedures for full-scale vehicle crash testing of guardrails were first published in the Transportation Research Board (TRB) Highway Research Correlation Services Circular 482 in This one-page document specified vehicle mass, impact speed, and approach angle for the crash tests. In 1974, the National Cooperative Highway Research Program (NCHRP) Report 153: Recommended Procedures for Vehicle Crash Testing of Highway Appurtenances was published to address questions that were not covered in Circular 482. This 16-page document provided a more complete set of testing procedures. Transportation Research Circular 191, published in 1978, addressed minor changes needed to address particular problem areas in NCHRP Report 153. In 1980, National Cooperative Highway Research Program (NCHRP) Report 230: Recommended Procedures for the Safety Performance Evaluation of Highway Safety Appurtenances was published to broaden the scope of NCHRP Report 153. This 36-page document incorporated new procedures, updated the evaluation criteria, and brought the procedures up to date with available technology and practices. This document served as the primary reference for full-scale crash testing of highway safety appurtenances in the U.S. and in many other parts of the world. During the subsequent decade, the evolution of roadside safety concepts, technology, and practices necessitated an update to NCHRP Report 230. Reasons included significant changes in the vehicle fleet, the emergence of new barrier designs, increased interest in matching safety performance to levels of roadway utilization, and advances in computer simulation and other evaluation methods. The resulting document, National Cooperative Highway Research Program (NCHRP) Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features, was published in The AASHTO Manual for Assessing Safety Hardware (MASH), 2009, is an update to and supersedes NCHRP Report 350 for the purposes of evaluating new safety hardware devices. This publication marks the first time that AASHTO has officially adopted crash-testing procedures for use in assessing roadside hardware. Previous editions were published as research reports from TRB and NCHRP. In addition, it should be noted that MASH does not supersede any guidelines for the design of roadside safety hardware, which are contained within the AASHTO Roadside Design Guide.

3 viii Manual for Assessing Safety Hardware MASH was developed through NCHRP Project 22-14(02), Improvement of Procedures for the Safety-Performance Evaluation of Roadside Features, and contains revised criteria for impact performance evaluation of virtually all highway safety features. Updates to MASH include increases in the size of several test vehicles to better match the current vehicle fleet, changes to the number and impact conditions of the test matrices, and more objective, quantitative evaluation criteria. An implementation plan for MASH that was adopted jointly by AASHTO and FHWA states that all highway safety hardware accepted prior to the adoption of MASH using criteria contained in NCHRP Report 350 may remain in place and may continue to be manufactured and installed. In addition, highway safety hardware accepted using NCHRP Report 350 criteria is not required to be retested using MASH criteria. However, new highway safety hardware not previously evaluated must utilize MASH for testing and evaluation.

4 ix TABLE OF CONTENTS Chapter 1 Introduction PURPOSE AND SCOPE UNDERLYING PHILOSOPHY PERFORMANCE LIMITATIONS SAFETY FEATURES TEST LEVELS INTERNATIONAL HARMONIZATION ANALYTICAL AND EXPERIMENTAL TOOLS ORGANIZATION OF REPORT...7 Chapter 2 Test Matrices and Conditions GENERAL Impact Conditions Tolerances on Impact Conditions Safety Feature Orientation TEST MATRICES Longitudinal Barriers General Description of Tests Terminals and Crash Cushions General Description of Tests Other Terminals and Crash Cushion Systems Truck- and Trailer-Mounted Attenuators and Variable Message Sign and Arrow Board Trailers General Description of Tests Support Structures, Work-Zone Traffic Control Devices, Breakaway Utility Poles, and Longitudinal Channelizers General Description of Tests Roadside Geometric Features and Pavement Discontinuities IMPACT POINT FOR REDIRECTIVE DEVICES General Longitudinal Barriers Tests with 1100C and 2270P Vehicles Tests with 10000S, 36000V, and 36000T Vehicles Terminals and Redirective Crash Cushions Test Test Test Test SIDE IMPACT...54 Chapter 3 Test Installation GENERAL TESTING SITE SOIL Standard Soil Soil Strength Special Soils Embedment of Test Article Special Structures TEST ARTICLE General Installation Details...64

5 x Manual for Assessing Safety Hardware Longitudinal Barriers Terminals and Crash Cushions Support Structures, Work-Zone Traffic Control Devices, and Breakaway Utility Poles Truck-Mounted and Trailer-Mounted Attenuators (TMAs) Test Installation Documentation Longitudinal Barriers and Longitudinal Channelizers Terminals and Crash Cushions Support Structures, Work-Zone Traffic Control Devices, and Breakaway Utility Poles Truck-Mounted and Trailer-Mounted Attenuators (TMAs) Test Installation Disposal...69 Chapter 4 Test Vehicle Specifications GENERAL TEST VEHICLE DESCRIPTIONS Production Vehicles Test Vehicle Mass Ballast Propulsion, Guidance, and Braking Vehicle Damage Surrogate Occupants Documentation Surrogate Test Vehicles Truck-Mounted and Trailer-Mounted Attenuator (TMA) Support Vehicle VEHICLE INSTRUMENTATION Instrumentation Specifications Accelerometer and Rate Gyro Placement and Data Reduction...88 Chapter 5 Evaluation Criteria GENERAL STRUCTURAL ADEQUACY OCCUPANT RISK POST-IMPACT VEHICULAR TRAJECTORY GEOMETRIC FEATURES...98 Chapter 6 Test Documentation GENERAL REPORTING RECOMMENDATIONS General Information Report Contents Findings Presentation Formats Assessment ELECTRONIC DATA Chapter 7 In-Service Performance Evaluation PURPOSE OBJECTIVES IN-SERVICE PERFORMANCE EVALUATION PROGRAM New Feature Evaluation Continuous Monitoring DISCUSSIONS Appendix A Commentary CHAPTER ONE A1.2 UNDERLYING PHILOSOPHY CHAPTER TWO A2.1 GENERAL A2.1.1 Impact Conditions A2.1.2 Safety Feature Orientation A2.2.1 Longitudinal Barriers A2.2.2 Terminals and Crash Cushions...123

6 xi A2.2.3 Truck-Mounted Attenuators (TMA) A2.2.4 Support Structures, Work-Zone Traffic Control Devices, Breakaway Utility Poles, and Longitudinal Channelizers A2.3 IMPACT POINT FOR REDIRECTIVE DEVICES A Tests with 1100C and 2270P Vehicles A Tests with 10000S, 36000V, and 36000T Vehicles CHAPTER THREE A3.2 TESTING SITE A3.3 SOIL A3.3.1 Standard Soil A3.3.2 Soil Strength A3.3.3 Special Soils A3.3.4 Embedment of Test Article A3.4 TEST ARTICLE A Longitudinal Barriers A Truck-Mounted Attenuators (TMA) CHAPTER FOUR A4.2 TEST VEHICLE DESCRIPTIONS A4.2.1 Production Vehicles A Test Vehicle Mass A Ballast A Vehicle Damage A Surrogate Occupants A4.2.2 Surrogate Test Vehicles A4.2.3 TMA Support Truck A4.3.1 Instrumentation Specifications A4.3.2 Acceleration and Rate Gyro Placement and Data Reduction CHAPTER FIVE A5.1 GENERAL A5.2 STRUCTUAL ADEQUACY A5.3 OCCUPANT RISK A5.4 POST-IMPACT VEHICULAR TRAJECTORY A5.5 GEOMETRIC FEATURES CHAPTER SIX A6.1 GENERAL REPORTING RECOMMENDATIONS CHAPTER SEVEN A7.1 PURPOSE Appendix B Soil Strength Performance Test B1 Purpose B2 Application B3 Instrumented Post B4 Post Placement B5 Dynamic Test B6 Assurance of Soil Performance Appendix C Electronic & PhotographicInstrumentation Specifications Appendix D Analytical and Experimental Tools D1 Useful Techniques D1.1 Structural Design D1.2 Static Tests D1.3 Computer Simulations D1.4 Laboratory Dynamic Tests D1.5 Gravitational Pendulum D1.6 Drop Mass/Dynamic Test Device D1.7 Scale Model D1.8 Bogie Test D2 Comparison of Techniques...209

7 xii Manual for Assessing Safety Hardware Appendix E Measurement of Vehicle Deformation E1 Pre-Impact Measurements E2 Post-Impact Measurements E3 Photographic Documentation E4 Procedure for Measuring Exterior Crush Appendix F Determination of THIV, PHD, and ASI F1 Introduction F2 A Guide to the Measurement of the Theoretical Head Impact Velocity (THIV) and the Post-Impact Head Deceleration (PHD) F2.1 General F2.2 Theoretical Head Impact Velocity (THIV) F2.3 Post-Impact Head Deceleration (PHD) F2.4 Summary of Procedure to Compute THIV and PHD F3 A Guide to the Measurement of the Acceleration Severity Index (ASI) F3.1 Procedure F3.2 Summary Appendix G Occupant Risk Estimation for 1500A Vehicle G1. Introduction G2. Occupant Risk Values for 1500A Vehicle G2.1 Procedure Details Appendix H Test Vehicle Selection Procedures Glossary References and Bibliography...249

8 xiii LIST OF FIGURES Figure 2-1. Impact Conditions for Longitudinal Barrier Tests...15 Figure 2-2. Impact Conditions for Terminal and Redirective Crash Cushion Tests...21 Figure 2-3. Impact Conditions for Non-Redirective Crash Cushion Tests...23 Figure 2-4. Impact Conditions for TMA...29 Figure 2-5. Impact Conditions for Support Structures, Work-Zone Traffic Control Devices, and Breakaway Utility Poles...34 Figure 2-6. Critical Impact Point for Test 10, Test Level Figure 2-7. Critical Impact Point for Test 10, Test Level Figure 2-8. Critical Impact Point for Test 10, Test Levels 3, 4, 5, and Figure 2-9. Critical Impact Point for Test 11, Test Level Figure Critical Impact Point for Test 11, Test Level Figure Critical impact point for Test 11, Test Levels 3, 4, 5, and Figure Critical Impact Point for Test 20, Test Level Figure Critical Impact Point for Test 20, Test Level Figure Critical Impact Point for Test 20, Test Levels 3, 4, 5, and Figure Critical Impact Point for Test 21, Test Level Figure Critical Impact Point for Test 21, Test Level Figure Critical Impact Point for Test 21, Test Levels 3, 4, 5, and Figure Critical Impact Point for Test 34 on Non-Gating Crash Cushions...53 Figure 3-1. Recommended Summary Sheet for Strong Soil Test Results...60 Figure 3-2. Example of Test Day Static Soil Strength Documentation...61 Figure C and 1500A Vehicle Parameters...80 Figure P Vehicle Parameters...81 Figure S Vehicle Parameters...82 Figure V Vehicle Parameters...83 Figure T Vehicle Parameters...84 Figure 4-6. Recommended Vehicle Coordinate System...88 Figure 5-1. Exit Box for Longitudinal Barriers...98 Figure 6-1. Recommended Format of Summary Sheet for Crash Test Results Figure 6-2. Example of Recommended Summary Sheet for Crash Test Results Figure 7-1. Flowchart of the In-Service Performance Evaluation Process (108) Figure A-1. Accelerometer Placement Figure B-1. Instrumented Post Figure B-2. Dynamic Test Configuration Figure B-3. Dynamic and Static Test Results for Standard Post Test Figure B-4. Static Soil Test Figure B-5. Test Day Static Load Test Compared to Standard Test Figure E-1. Pre-Impact Measurement Figure E-2. Placement of Swivel Laser Bracket Figure E-3. Measurement of Vertical Positions Figure E-4. Vehicle Deformation Spreadsheet Figure E-5. Reference Line Configuration Figure E-6. Field Length Measurement Figure E-7. Crush Depth Measurements Figure E-8. Crush Depth Measurements Figure F-1. Vehicle and Ground Reference Frames Figure F-2. Impact of the Theoretical Head on the Left Side...222

9 xiv Manual for Assessing Safety Hardware LIST OF TABLES TABLE 1-1. Test Levels...6 TABLE 2-1. Vehicle Gross Static Mass Upper and Lower Limits...12 TABLE 2-2. Recommended Test Matrices for Longitudinal Barriers...14 TABLE 2-3. Recommended Test Matrices for Terminals and Crash Cushions...18 TABLE 2-4. Recommended Test Matrices for Truck- and Trailer-Mounted Attenuators...28 TABLE 2-5. Recommended Test Matrices for Support Structures, Work-Zone Traffic Control Devices, and Breakaway Utility Poles...33 TABLE 2-6. Critical Impact Point for Rigid Barrier Tests with 1100C and 2270P Vehicles...39 TABLE 2-7. Critical Impact Point for Heavy Vehicle Tests...52 TABLE 4-1. Recommended Properties of 1100C, 1500A, and 2270P Test Vehicles...75 TABLE 4-2. Recommended Properties of 10000S, 36000V, and 36000T Test Vehicles...76 TABLE 5-1. Safety Evaluation Guidelines...93 TABLE 6-1. Recommended Table of Contents for Crash Test Reports TABLE 6-2. Recommended Format for Reporting of Findings TABLE 6-3. Example of Recommended Assessment Summary Page for Individual Crash Tests TABLE 6-4. Example of Recommended Assessment Summary Page for Multiple Crash Tests TABLE A-1. Properties of Common Barrier Rail Elements TABLE A-2. Wood Post Properties TABLE A-3. Dynamic Yield Forces of Posts Embedded in Strong Soil TABLE D-1. Sources for Safety Feature Information TABLE D-2. Summary of Highway Safety Computer Programs TABLE D-3. Safety Feature Development Techniques TABLE H-1. Small Car Weights and Sales Volumes TABLE H-2. Light Truck Weights and Sales Volumes TABLE H-3. Center-of-Gravity Heights of Sport Utility Vehicles and Pickups TABLE H-4. Candidate Test Vehicle Dimensions...241