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86 Full-Scale Testing and Results 6.1 Introduction Most longitudinal barriers used on U.S. highways have been tested to the generalized requirements under NCHRP Report 350 or MASH. These testing procedures focus on pro- tocols that allow repeatability and convenient comparison of the performance results to the requirements. Because it is considered impractical to test for all conditions under which a barrier might be placed, tests are typically conducted on straight sections and level surfaces because these are the most common. Longitudinal barriers are subjected to impacts with large and small vehicles at the specific speeds associated with a given test level. This implies that not all possible impact conditions are evaluated. Longitudinal barriers used in appli- cations where the road is curved, banked, or the barrier is placed on a surface adjacent to the road are among those situations that have had very limited testing. The literature review found very few references to research or testing for barriers on or near slopes, and there is no known âacceptanceâ testing for applications in such situations. A clear indication of a safety problem could not be discerned from available crash data, because the crash reports provide limited details about the barriers and the conditions under which they were deployed. However, it would seem that there may be different vehicle-to-barrier interfaces and consequently impacts on the safety performance of the barrier. Further, it was noted that under current practice there seems to be limited guidance for the design, placement, and installation of barriers for CSRS. The limited understanding of the influences of vary- ing curve, roadway, barrier, and placement features provided the impetus for this NCHRP project to analyze barrier per- formance for deployments of longitudinal barriers on CSRS. 6.2 Background Different types of longitudinal barriers are typically used on CSRS and the roadway and placement conditions vary. The VDA and simulation analyses provided quantitative measures of the barriers and the conditions under which they were likely to have safety issues. While there are many conditions that were candidates for testing, it was possible to conduct a small set of full-scale crash tests to validate the simulation analyses. The results of the simulation analyses were used to select the test cases. The analyses showed that the NJ concrete barriers were the most override prone of the concrete barriers, so it did not warrant crash testing. Similarly, the MGS barrier due to its greater height showed limited tendency to have safety perfor- mance issues. The most common barrier analyzed, the G4(1S) W-beam guardrail, did indicate serious problems in the ini- tial analyses at the 27Â¾-in. height, and to a lesser degree at the 29-in. height. Thus, the decision was made to focus the testing on the G4(1S) W-beam barrier. The analyses indicated that the propensity for barrier override or underride was lower for higher radius curves across all superelevation conditions. Because the sharpest 641-ft radius curves with 12% superel- evation were noted to be rarely used, the focus for the testing was on the 833-ft radius curves with 6% superelevation. Two shoulder widthsâ4 ft and 8 ftâwere selected for testing with the barrier placed at the edge of the shoulder. These cases are highlighted in Table 6.1. These conditions were considered to lie on either side of the boundary between passing and failing. The testing for these options was conducted under the cur- rent MASH crashworthiness requirements. The Research Team recognized that testing the performance of longitudinal barriers on CSRS would present challenges. Therefore, a testing scheme was proposed that would focus on the most critical aspects that influence viability. The essentials of this scheme included the following: â¢ Select the critical cases for testing, recognizing that it is likely that only two or three tests will be possible under the available project funds. â¢ Define the critical CSRS conditions to determine the extent of construction needed (e.g., if two different curve radii are C H A P T E R 6
87 Notes: * = Barrier performance extrapolated based on other simulation results. Simulation case numbers are shown in parentheses. Mar. = marginal passing. Table 6.1. Simulation summary of the cases selected for testing.
88 considered, it will be necessary to incur expenses to tear down the first road set up and build a second roadway set up). â¢ Use vehicle dynamics analyses results to determine the appropriate vehicle launch position and speed to reflect the desired impact conditions in the âfree-wheelingâ mode. Simulation would be used to estimate the neces- sary âlaunchâ or âreleaseâ speed from the track accelerator to attain the required MASH speed at the barrier impact point (or at least within speed tolerances). â¢ A sloped transition section (ramp or inclined plane) from the release point on the track accelerator to the impact point was constructed to represent the CSRS. The prelimi- nary VDA suggested that the incline should rise about 2 ft over a 30-ft to 60-ft paved transition section that leads into a 24-ft-wide paved CSRS segment with shoulder. â¢ The VDA results were used to identify critical combina- tions of barriers and curve features that may represent critical cases as candidates for testing. â¢ The CSRS segment was constructed accommodate the installation of an adequate length of barrier for testing. A gentle back slope was placed behind the barrier using fill. Accommodations were made to prevent the impact testing from disrupting the road base or foundation to allow for multiple tests across the roadway. â¢ Preliminary trajectory tests without barriers were con- ducted to define the degree of side drift and speed loss that might occur so that barriers could be impacted at or near a 25Â° angle. â¢ The barrier was set up to be tested with provisions to capture the normal metrics and any additional items that may be useful to understand barrier safety performance on CSRS. Specific details were finalized after the preliminary tests confirmed the necessary post positions to meet MASH requirements. The objective of this task was to provide test data for the analyses of barriers on CSRS to rigorously validate the simu- lation results of the most critical cases. The critical cases were determined using simulation analysis and the experience of the Team and the NCHRP Project 22-29A panel. Table 6.1 shows the conditions analyzed for the G4(1S) barriers that were considered the most important to test. The 254-m (833-ft) radius with 6% superelevation was a mid-range con- dition and the tests were bracketed to fall in the area where âpassâ and âfailâ conditions were noted in the simulation analysis. This was necessary because the project budget lim- ited the efforts to two or three tests. The preliminary launch tests without impacts allowed the vehicles to be reused and thus allowed multiple runs to assess speeds and trajectories that greatly increased the probability that the tests would be successful. The tests were designed and set up to capture the typical data needed to evaluate TL-3 crashworthiness, as well as additional data to understand vehicle dynamics and barrier interface physics that could be useful in determining critical factors that would influence design and placement for the selected CSRS applications. This chapter describes the efforts to set up and execute the full-scale tests at the FHWAâs Federal Outdoor Impact Laboratory (FOIL) to validate the results of the simulation analyses. 6.3 Testing Requirements, Criteria, and Facility Three full-scale crash tests were conducted. The project costs included three test vehicles, construction of the road section with an 833-ft radius and 6% superelevation for two shoulder widths, and installations of an appropriate length of G4(1S) longitudinal barrier for each test. The two shoulder widths required that the positioning of the posts consider the prescribed critical impact points. The barrier was installed by a commercial barrier contractor following standard prac- tices. The tests were conducted in accordance with MASH requirements. Complete details of the testing are provided in Appendix E. The following sections provide an overview of the tests and the results. 6.3.1 MASH Requirements The tests were conducted in accordance with the current crashworthiness evaluation protocols and requirements under MASH. The MASH testing requirements and protocols included the following (with variations in italics): â¢ Test Set Up. â Ordinarily, the barrier should be installed so that the impact test can occur on level terrain with an unrestricted area to observe vehicle redirection trajectory after impact per MASH (AASHTO 2009, page 57). These tests varied in that a sloped surface was constructed to represent the condition for a vehicle traversing a CSRS prior to barrier impact. â Minimum barrier installation lengths shall be sufficient to indicate the maximum deflections and opportunities for snagging or vaulting. The lengths need to be suffi- ciently long to develop the necessary rail tensions. These vary by type of barrier. For W-beam guardrail (semi- rigid), the length needs to be no less than 100 ft. â Soil used for embedment must comply with AASHTO âstrong soilâ (M 147). Tests were conducted to dem- onstrate adequate strength.
89 â¢ Testing Required for Various Test Levels and Applicable Criteria from MASH (AASHTO 2009, Table 2-2). The tests outlined in MASH have varying purposes. Test 10 at any test level is intended to demonstrate that the barrier will provide a continuous strength and capability to redirect the errant vehicle. Concerns focus on underride, wheel snag, rollover, and head slap issues. Test 11 focuses on demonstrating the barrier has adequate strength to restrain heavier vehicles. Rollovers and occupant risk are critical concerns. The test requirements are given in the table below: not penetrate, underride, or override the installation, although controlled lateral deflection of the test article is acceptable. Occupant Risk D. Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present an undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformation of, or intrusions into, the occupant compartment should not exceed limits set forth in Section 5.3 and Appendix E of MASH. F. The vehicle should remain upright during and after collision. The maximum roll and pitch angles are not to exceed 75Â°. H. OIV should satisfy the following: longitudinal and lateral OIV 30 ft/s (preferred), 40 ft/s (maximum). I. ORA should satisfy the following: longitudinal and lateral ORA should be less than 15.0 g (preferred), 20.49 g (maximum). Vehicle Trajectory L. The vehicle shall exit the barrier within the exit box. The results from each test were used to evaluate the barrier safety performance based on these criteria. 6.3.3 FOIL Test Facility The FOIL is a full-scale outdoor crash test facility primar- ily designed to test the impacts of vehicles on roadside safety hardware. The test vehicles are propelled into the barriers using a specially designed hydraulic propulsion system. The vehicles are accelerated on a 220-ft fixed concrete track. The propulsion system is capable of pulling an 8,000-kg vehicle up to 60 mph. A 2270P test vehicle can be brought to a speed in excess of 70 mph. The test vehicles are released into a run- out area that is 160 ft Ã 320 ft. Barriers up to 450 ft in length (usually at 25Â° relative to the track) can be installed in the runout area at the end of the track. Figure 6.1 provides an aerial view of the layout of the FOIL facility. 6.4 Testing Approach 6.4.1 Roadway Segment Construction and Barrier Installation Figure 6.2 shows the set up for the preliminary and full- scale tests. A representation of a CSRS (including sloped shoulder) was constructed at the end of the FOIL track adja- cent to the runout area. The road section and shoulder were placed at an angle relative to the FOIL track to achieve the Test Level Test Number Vehicles Impact Speed Impact Angle Evaluation Criteria TL-3 3-10 1100C 62 mph (100 kph) 25o A, D, F. H, I 3-11 2270P 62 mph (100 kph) 25o A, D, F. H, I â¢ Impact Conditions. â Speeds and tolerance limits (62 mph Â± 2.5 mph) â Angle (25Â° Â± 1.5Â°) â¢ Test Vehicles (Table 2-1). â 1100C: small car (2,450 lb Â± 55 lb) â 2270P: pickup truck (5,000 lb Â± 110 lb) â¢ CIPs. â Semi-rigid barriers: CIP is determined from charts 2.8 and 2.9 to reflect the design features of the device mea- sured from a hard point such as a post. â¢ Evaluation Metrics and Instrumentation. The vehicle and test article need to be instrumented according to MASH protocols to capture data in a manner that will allow comparison to similar tests and with the appropriate levels of accuracy. MASH does not have any specific requirements for test- ing barriers for installation on curves, but there is general language suggesting that barriers should be tested for non- typical applications (AASHTO 2009, Section 2.2.5). It is assumed that while curvature might influence impact angles, the impacts should be within similar tolerance ranges. 6.3.2 MASH Evaluation Criteria The performance of the longitudinal barriers in the crash simulations was evaluated in accordance with the criteria presented in MASH. The barrier performance was evaluated on the basis of three factors: structural adequacy, occupant risk, and post-impact vehicle trajectory. For longitudinal barriers, the following evaluation criteria have to be met: Structural Adequacy A. Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should
90 desired impact angle with the barrier. The longitudinal barrier was installed adjacent to the road section at the desired lat- eral locations and vertical orientation. A transition section was constructed between the track and road section to reflect CSRS conditions and achieve the desired vehicle position and orientation for impact. Prior to barrier installation, itera- tive preliminary tests were conducted to verify that the desired vehicle release speed (at the end of the FOIL track) and vehicle- to-barrier impact angle could be achieved. The barrier posts were set using these parameters to achieve critical impact point requirements in the tests. The G4(1S) barrier was placed at 4-ft and 8-ft offsets to reflect the selected shoulder widths. The following were some of the challenges in this set up that influenced construction of the tests: â¢ The elevation along the barrier line will be uniform for at least the length of the longitudinal barrier installation. â¢ The area along this line must be wide enough to allow for post installation and provide sufficient operating space for barrier construction equipment. â¢ The raised inclined plane area needs to have sufficient side slopes to ensure stability of the barrier installation for the impact tests. â¢ The actual paved area does not need to cover the entire length of the barrier installation but should be wide enough to allow assessment of the exit box. â¢ The slope and barrier line need to be set to ensure impacts at the nominal 25Â° angle when the vehicle is launched in a free-wheeling mode. The exact construction plan was refined in discussions with contractors and barrier installation experts. Ultimately, a CSRS roadway/shoulder section was represented by an asphalt pad that was 12.2 m (140.0 ft) Ã 7.3 m (24.0 ft). The roadway portion of the asphalt pad was 4.9 m (16.0 ft) with a 6% super elevation. The shoulder portion of the asphalt pad was 3 m (10.0 ft) with a 2% decline. The entire roadway/shoulder was installed with a 254-m (833-ft) radius road curvature. 6.4.2 Test Vehicles Test vehicles conforming to MASH requirements for 2270P pickup trucks were procured considering age and vehicle features. Older pickups and other vehicles were procured for preliminary tests. The vehicles were inspected to ensure that there was no damage that would influence the test. Measure- ments were made, instrumentation installed, and all fluids and the battery removed. The dummy, instrument tray, battery box, data acquisition system, and brake system were installed as pre- scribed. The final weights were recorded on standard forms for recording test data. Instrumentation was certified to have valid current calibrations. Protocols for accelerometers were followed to meet MASH requirements. Other instrumentation was installed to FOIL protocols. A typical test vehicle is shown in Figure 6.3. A description of the test instrumentation and data acquisition systems was fully documented (see Appendix E). 6.4.3 Test Articles Test articles, namely the G4(1S) barrier, were installed by an established roadside hardware contractor and labeled to monitor the impact effects on parts of the system. Critical to effective testing for this novel roadway set up was ensuring that the critical impact point was achieved. The preliminary tests determined the range of drift that might be expected as the vehicle is in free-wheeling mode traversing the transi- tion section. Using this range of drift, the barrier position was chosen such that the vehicle would make first contact as close Track Runout Area Figure 6.1. Aerial view of the FHWA FOIL facility.
Figure 6.2. Test set up plan for CSRS section constructed for testing at FOIL.
92 as possible to the critical impact point. This was achieved by identifying the intersection point between the expected vehicle trajectory and the barrier line and using it to deter- mine where the first impacted post needed to be installed. The other posts were then positioned relative to this post for the length of the test article installation. The tested articles consisted of a G4(1S) W-beam guard- rail with 25 standard steel posts and blockouts with 2 Type-T anchor assembly end terminations for a total of 29 posts (Figure 6.4). The spacing of each post was 1.9 m (6 ft 3 in.) for a total length of 53.3 m (175 ft). The top height of the G4(1S) W-beam rail was set at 73.7 cm (29 in.). The posts were embedded with a hydraulic hammer in Virginia Depart- ment of Transportation (VDOT) 21A soil, which conforms to the standard for strong soil (Figure 6.5). The photos show multiple views of the installation process and resulting test article and test bed. This process was repeated for tests repre- senting 4-ft and 8-ft shoulders. Since MASH requires that soil conditions meet specific requirements when the barrier function depends on strength developed through in-ground embedment, an area around each post location was excavated with a 3-ft diameter auger for a depth greater than the expected post embedment. The soil from each of these pits was replaced with strong soil. The strong soil was compacted in 6-in. lifts and nuclear density meter readings were used to ensure full compaction. Addi- tional pendulum testing was conducted as necessary to pro- vide soil condition data. Soil strength was determined by the specification required in MASH that must be verified before the test is conducted (AASHTO 2009, Chapter 3 and Appendix B). Prior to the full-scale crash testing, dynamic pendulum and static pull testing were conducted in accordance with MASH recom- mendations to ensure that the soil used in the tests complied with the MASH criteria. The tests consisted of impacting (dynamic) or pulling (static) a W6 Ã 15 post that is 1.8 m (6 ft) in length and embedded 101.6 cm (40 in.) in standard strong soil. The post was impacted/pulled at a height of 63.5 cm (25 in.) and the load was measured to verify the minimum soil resistance. The minimum dynamic load required for post deflections between 12.5 cm (5 in.) and 63.5 cm (25 in.) is 33-kN (7.5-kip) force. The soil type and compaction procedure were then used for all G4(1S) instal- lations. Static pull tests were conducted the day of the crash test and compared with the previously conducted static pull tests to ensure an adequate strength (higher than 90% of the initial test). These posts were compacted the same day as the test article installation and using the same soil material. 6.4.4 Test Procedures The tests were set up and performed in accordance with the recommended MASH procedures. High-speed cameras, accelerometers, rate transducers, and speed measuring devices were used to capture the vehicle and barrier responses during the impact. Eight high-speed cameras were used for full-scale crash tests. One camera was placed over the impact region to capture an overhead view. Seven additional cameras were placed at different locations surrounding the impact region to capture left, right, front, rear, and isometric views of the crash event. Two tri-axial accelerometers were mounted at the vehicle center of gravity to measure the x-, y-, and z-accelerations of the vehicle. This data was used to compute the ORAs and OIVs. Additionally, two tri-axial rate trans- ducers were used to measure the vehicle roll, pitch, and yaw. Contact switches were installed on the vehicle and test article to synchronize time zero during the impact for the sensor data and high-speed movies. For each test, details of the set ups, test execution, and results were documented. The documentation followed the standard protocols established for the FOIL that comply with MASH requirements. The test documentation includes materials describing the test set up and results, as well as vari- ous digital images and data from physical measurements or instrumentation installed on the test vehicles and articles. These are provided in Appendix E. A detailed report documenting all aspects of the tests was generated that included the following information: â¢ Test Background: A detailed description of the test with multiple images of the test article is provided. â¢ Test Set Up Description: A detailed description of the set up of the test article in the test setting is provided including description of the elements, their locations, proximity to the test track, and other details. Pictures are also included. Figure 6.3. Typical MASH 2270P vehicle for crash testing.
Figure 6.4. CSRS W-beam test article set up.
94 (a) (b) (c) (d) (e) (f) Figure 6.5. Test article and construction for full-scale crash tests.
95 â¢ Test Article Design: Plan sheets showing the dimensions, connections, and configurations of the test article are provided. â¢ Test Article Installation: Descriptions of the efforts to con- struct or install the test article are provided along with all relevant support documentation (e.g., compaction metrics). â¢ Test Vehicle: The condition, mass, size, tires, and features of each test vehicle are noted. â¢ Impact Description: The nature of the impactor and its speed are documented. â¢ Test Article Damage: Images and measurements of damage, deflections, and ruptures of the test article (e.g., barrier) are described and images stored. â¢ Test Vehicle Damage: The location and nature of the damage to the test vehicle is described and recorded. â¢ Performance Assessment: Comparisons of test results to MASH requirements are provided to evaluate barrier performance. â¢ Test Summary: A MASH requirement is that a crash test summary diagram be created that shows a sequential view of the test and provides all pertinent data derived. â¢ Digital Impact Data: Digital impact data is provided. â¢ Video Images: Video images are provided. Variations of these basic elements occurred as necessary to capture the unique nature of these tests. 6.5 Preliminary Tests Given the nature of these tests, a series of non-destructive tests were conducted to determine the following: â¢ Launch Speeds: It was critical to be certain that the vehicle propulsion system was set to the appropriate parameters to ensure that a vehicle would impact the barrier at the desired speed. Several tests measured the speed at possible impacts points. Vehicles were instrumented to capture accelerations and roll, pitch, and yaw rates for compari- son with the vehicle dynamics results and to determine the effects of CSRS on vehicle-to-barrier interface. â¢ Trajectories: The paths of the vehicles were monitored to determine if the road and shoulder slopes caused the vehicle to deviate from the desired trajectory to the impact point. Figure 6.6 shows a top view of one of the preliminary tests that was conducted to determine the appropriate launch speeds and drift effects on vehicle trajectory. The yellow line on the road surface reflects the direct extension of the track axis. The vehicle drift is the distance between the centerline of the vehicle (indicated by the green line) and the yellow line. Multiple runs were made for varying launch speeds to deter- mine the average drift. The graphs in Figure 6.7 show typical results from these tests. The top graph shows the changes in the z-axis displace- ment measured from a string potentiometer placed in the front-right suspension of the vehicle. The z-axis displacements from three repeat tests are shown in the graph. Time zero indicates the time the vehicle would first come in contact with the barrier. Note that as the vehicle accelerates down the track, the z-displacement increases as the acceleration pitches the vehicle up then reaches a stable level. Once the vehicle is released, the suspension starts to return to its zero value. As the vehicle reaches the transition section and enters the super elevated road section, the front suspension starts to compress leading to a decrease in the z-displacement (nega- tive). Once all four wheels are on the road section, the sus- pension starts to recover again, and the z-axis displacement goes back to zero. After time zero, the side slope is encoun- tered, causing another disruption in the front suspension. The important aspect of this is the indication of the z-axis displacement at the projected impact point. It is near zero suggesting that the vehicle is at the position of equilibrium. Figure 6.8 shows the decrease in velocity as the vehicle free wheels to the impact point. For the tests that had a launch speed of 100 km/h (62 mph), only about 2 km/h (1.25 mph) were lost as the vehicle climbed the inclined transition sec- tion. These tests provided the information necessary to set the launch speed target for the vehicle to meet the goal of having it impact the barrier at 62 mph (100 km/h) after traveling up the incline of the CSRS to impact the barrier at the critical speed. The release speed for all three actual tests was targeted for 102 km/h (63.25 mph). -25.5Â° Figure 6.6. Top view from typical preliminary test.
96 Figure 6.7. Suspension z-displacement from preliminary test. Figure 6.8. Typical vehicle speed profile from preliminary test.
97 6.6 Full-Scale Crash Testing Results Three full-scale tests were conducted to reflect MASH Test 3-11 requirements simulated for a 254-m (833-ft) radius CSRS with a 6% superelevation for a G4(1S) W-beam barrier with the 2270P test vehicle. Note that conditions were simi- lar for all these tests except for the wider shoulder width in the last test. There were also some normal variations in the vehicle and impact parameters. More details are provided for each test in the following subsections. 6.6.1 Test 16004 This test was performed using specifications for MASH Test 3-11. This test consisted of a 2009 Chevrolet Silverado weighing 2,315 kg (5,104 lb) impacting a G4(1S) W-beam guardrail barrier with two Type-T anchor assembly end terminations on a 254-m (833-ft) radius curve with a 6% superelevation on an asphalt roadway/shoulder surface. The G4(1S) W-beam guardrail barrier was placed at the end of a 1.2-m (4-ft) shoulder with a â2% slope. The barrier was installed to follow the curvature of the roadway/shoulder. The set up is shown in Figure 6.9. Figure 6.10 and Figure 6.11 provide sequential views of the behavior of the vehicle in the impact. Additional test details and photos are provided in Appendix E. The test vehicle began impacting the G4(1S) W-beam guardrail barrier at post 11. The impact was approximately 19.1 m (62.5 ft) downstream from the beginning of the bar- rier installation and 34.3 m (112.5 ft) upstream from the end of the barrier installation. This was approximately 0.75 m (2.5 ft) upstream from the desired critical impact point. When the barrier was impacted some snagging occurred, but the vehicle was redirected. (a) (b) (c) (d) Figure 6.9. Vehicle and barrier set up for Test 16004.
98 0.00 s 0.16 s 0.31 s 0.47 s 0.63 s 0.79 s 0.94 s 1.10 s Figure 6.10. Sequential photographs for Test 16004 (rear isometric view).
99 0.00 s 0.09 s 0.17 s 0.26 s 0.34 s 0.43 s 0.51 s 0.60 s Figure 6.11. Sequential photographs for Test 16004 (front isometric view).
100 There was significant damage to the impacted area of the G4(1S) W-beam guardrail barrier. The damage to the bar- rier was contained between post 10 and post 16. There was considerable flattening of the W-beam guardrail with tearing. Also, there was significant twisting of the posts and broken blockouts. The damage to the barrier is shown in Figure 6.12. The 2009 Chevrolet Silverado had significant damage as shown in Figure 6.13. The majority of the damage came on the right-hand side of the vehicle because that was the impacted side. There was major denting to the passenger side of the vehicle. The front passenger side tire became detached during the impact and the passenger rear tire was flat after impact. The front and rear bumper had considerable damage to the passenger side but the driverâs side received minimal to no damage. The tires on the driverâs side remained undamaged during the impact. Table 6.2 contains the specific features of the test and the computed metrics from the various digital recording devices. The test vehicle was within the mass tolerance range (Â±50 kg) for testing requirements. The impact speed and angle were also within tolerance limits. The vehicle was redirected, although it experienced a high degree of yaw, pitch, and roll, and came to rest on its wheels. The vehicle had the front wheel sheared off and significant damage. The barrier was severely damaged, but the rail remained con- nected. The crash metrics computed from the instrumenta- tion on the vehicle are provided below. 6.6.2 Test 16010 This test was performed using specifications for MASH Test 3-11. This test consisted of a 2009 Chevrolet Silverado (a) (b) (c) (d) Figure 6.12. Damage to test article for Test 16004.
101 General Information Test Agency: FOIL Test Number: 16004 Test Date: 04/14/2016 Test Article: G41S W-Beam Guardrail Test Vehicle Description: 2270P Silverado Test Inertial Mass: 2,315 kg Gross Static Mass: 3,085 kg Impact Conditions Speed: 100.0 km/h Angle: 25.0Â° Occupant Risk Factors Impact Velocity (m/s) at 0.1701 s x-direction 4.9 y-direction 4.5 THIV (km/h): 24.7 at 0.1721 s THIV (m/s): 6.9 Ridedown Accelerations (g) x-direction â7.5 (0.9691 to 0.9791 s) y-direction â7.7 (0.2571 to 0.2671 s) PHD (g): 10.1 (0.2536 to 0.2636 s) ASI: 0.71 (0.2518 to 0.3018 s) Max. 50msec Moving Avg. Accelerations (g) x-direction â5.7 (0.9402 to 0.9902 s) y-direction â6.0 (0.2517 to 0.3017 s) z-direction â3.6 (0.9490 to 0.9990 s) Max Roll, Pitch, and Yaw Angles (degrees) Roll (0.9487 s) Pitch (1.2232 s) Yaw â23.9 â36.5 25.4 (9.9888 s) Table 6.2. Data and results for Test 16004. (a) (b) Figure 6.13. Damage to test vehicle for Test 16004. installed to follow the curvature of the roadway/shoulder. The set up is shown in Figure 6.14. Figure 6.15 and Fig- ure 6.16 provide sequential views of the behavior of the vehicle in the impact. The test vehicle began impacting the G4(1S) W-beam guardrail barrier between post 11 and post 12. The impact was approximately 20 m (65.6 ft) downstream from the beginning of the barrier installation and 33.4 m (109.4 ft) upstream from the end of the barrier installation. When the barrier was impacted, it was flattened out and allowed vehicle override. The vehicle came to rest on the opposite side of the barrier. There was significant damage to the impacted area of the G4(1S) W-beam guardrail barrier. The damage to the bar- rier was contained between post 11 and post 15. There was a significant amount of flattening of the W-beam guardrail with tearing that allowed the vehicle to pass to the other side of the barrier. There were also broken blockouts, bolts at the posts pulled through, and significant post twisting at the impact area. The damage to the barrier is shown in Figure 6.17. The 2009 Chevrolet Silverado had significant damage. During the initial impact, the majority of the damage came on the right-hand side of the vehicle because that was the impacted side. The front passenger side tire became detached during impact; however, the other three tires remained intact and were undamaged. When the vehicle went to the opposite side of the barrier, it rolled onto its roof causing damage to the roof. The vehicle had sig- nificant damage to the cab, suspension parts, truck bed, and a broken windshield. The vehicle damage is shown in Figure 6.18. weighing 2,283 kg (5,033 lb) impacting a G4(1S) W-beam guardrail barrier with two Type-T anchor assembly end terminations on a 254-m (833-ft) radius curve with a 6% super elevation on an asphalt roadway/shoulder surface. The G4(1S) W-beam guardrail barrier was placed at the end of a 1.2-m (4-ft) shoulder with a â2% slope. The barrier was
102 (a) (b) (c) (d) Figure 6.14. Vehicle and barrier set up for Test 16010.
103 0.00 s 0.34 s 0.69 s 1.03 s 1.37 s 1.71 s 2.06 s 2.40 s Figure 6.15. Sequential photographs for Test 16010 (rear isometric view).
104 0.00 s 0.16 s 0.31 s 0.47 s 0.63 s 0.79 s 0.94 s 1.10 s Figure 6.16. Sequential photographs for Test 16010 (front isometric view).
105 (a) (b) (c) (d) Figure 6.17. Damage to test article for Test 16010. (a) (b) Figure 6.18. Damage to test vehicle for Test 16010.
106 General Information Test Agency: FOIL Test Number: 16010 Test Date: Times New Roman Test Article: G41S W-Beam Guardrail Test Vehicle Description: 2270P Silverado Test Inertial Mass: 3,085 kg Gross Static Mass: 2,283 kg Impact Conditions Speed: 100.0 km/h Angle: 25.0Â° Occupant Risk Factors Impact Velocity (m/s) at 0.2100 s x-direction 4.8 y-direction 3.8 THIV (km/h): 22.7 at 0.2149 s THIV (m/s): 6.3 Ridedown Accelerations (g) x-direction â6.1 (0.2730 to 0.2830 s) y-direction â6.0 (0.2153 to 0.2253 s) PHD (g): 8.0 ASI: 0.56 (0.2339 to 0.2439 s) (0.1288 to 0.1788 s) Max. 50msec Moving Avg. Accelerations (g) x-direction â5.1 (0.1249 to 0.1749 s) y-direction â3.7 (0.1952 to 0.2452 s) z-direction 3.5 (3.5260 to 3.5760 s) Max Roll, Pitch, and Yaw Angles (degrees) Roll â51.4 Pitch â50.0 Yaw â168.5 (2.3602 s) (4.1601 s) (3.8266 s) Table 6.3. Data and results for Test 16010. Table 6.3 provides the specific features of the test and the computed metrics from the various digital recording devices. The test vehicle was within the mass tolerance range (Â±50 kg) for testing requirements. The impact speed and angle were also within tolerance limits. The vehicle was not redirected. It experienced a high degree of yaw, pitch, and roll, and came to rest on its roof after vaulting over the bar- rier. The vehicle had the front wheel sheared off and signifi- cant damage. The barrier was severely damaged, but the rail remained connected. The crash metrics computed from the instrumentation on the vehicle are provided below. 6.6.3 Test 16015 This test was performed using specifications for MASH Test 3-11. This test consisted of a 2009 Chevrolet Silverado 2,268 kg (5,000 lb) impacting a G4(1S) W-beam guardrail barrier with two Type-T anchor assembly end terminations on a 254-m (833-ft) radius curve with a 6% superelevation on an asphalt roadway/shoulder surface. The G4(1S) W-beam guardrail barrier was placed at the end of a 1.2-m (4-ft) shoulder with a â2% slope. The barrier was installed to fol- low the curvature of the roadway/shoulder. The set up is shown in Figure 6.19. Figure 6.20 and Figure 6.21 provide sequential views of the behavior of the vehicle in the impact. The 2270P vehicle began impacting the G4(1S) W-beam guardrail barrier at post 13. The impact was approximately 24.8 m (81.3 ft) downstream from the beginning of the barrier installation and 28.6 m (93.7 ftp) upstream from the end of the barrier installation. When the vehicle impacted the barrier, the barrier was crushed allowing the vehicle to redirect. The vehicle came to rest on the impacted side of the barrier. There was significant damage to the impacted area of the G4(1S) W-beam guardrail barrier. The damage to the barrier was contained between post 13 and post 18. There was a sig- nificant amount of crushing of the W-beam guardrail. There were also broken blockouts, bolts at the posts pulled through, and significant post twisting at the impact area. The damage to the barrier is shown in Figure 6.22. The 2009 Chevrolet Silverado had significant damage. The majority of the damage came on the right-hand side of the vehicle because that was the impacted side. There was major denting to the passenger side of the vehicle. The front passen- ger side tire became detached during the impact due to bro- ken suspension parts and the passenger rear tire was flat after impact. The front and rear bumper had considerable damage to the passenger side but the driverâs side received minimal damage. The tires on the driverâs side remained undamaged during the impact. The vehicle damage is shown in Figure 6.23. Table 6.4 contains the specific features of the test and the computed metrics from the various digital record- ing devices. The test vehicle was within the mass tolerance range (Â±50 kg) for testing requirements. The impact speed and angle were also within tolerance limits. The vehicle was redirected, although it experienced a moderate degree of yaw, pitch, and roll, and came to rest on its wheels. The vehicle had the front wheel sheared off and significant dam- age. The barrier was severely damaged, but the rail remained connected. The crash metrics computed from the instru- mentation on the vehicle are provided below. 6.7 Test Results Evaluation The results from the tests are shown in Table 6.5 for the relevant MASH criteria to determine overall safety per- formance for G4(1S) W-beam barriers on CSRS tested. Note that the first and third tests were considered to âPass,â although the first test did not have the proper impact point. The vaulting/rollover in the second test âfailed.â In Test 16004, the impact point on the barrier was about 0.75 m (2.5 ft) off from the computed critical point based on MASH recommended methods. After additional preliminary testing, the test was repeated (Test 16010) and the vehicle impacted the barrier at the desired location. Test 16015 was then performed on the wider shoulder (8 ft) and again the desired impact location was achieved. The results from Tests 16010 and 16015 confirm the simulations results.
107 (a) (b) (c) (d) Figure 6.19. Vehicle and barrier set up for Test 16015.
108 0.00 s 0.16 s 0.31 s 0.47 s 0.63 s 0.79 s 0.94 s 1.10 s Figure 6.20. Sequential photographs for Test 16015 (rear isometric view).
109 0.00 s 0.11 s 0.22 s 0.33 s 0.43 s 0.54 s 0.65 s 0.76 s Figure 6.21. Sequential photographs for Test 16015 (front isometric view).
110 (a) (b) (c) (d) Figure 6.22. Damage to test article for Test 16015. (a) (b) Figure 6.23. Damage to test vehicle for Test 16015.
111 Test 16004 Test 16010 Test 16015 Structural Adequacy A: Test article should contain and redirect the vehicle; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Fail Pass Occupant Risk D: Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present an undue hazard to other traffic, pedestrians, or personnel in a work zone. Pass Pass Pass F: The vehicle should remain upright during and after the collision although moderate roll, pitch, and yaw are acceptable. Pass Fail Pass H: The occupant impact velocity in the longitudinal direction should not exceed 40 ft/s and the ORA in the longitudinal direction should not exceed 20 g. Pass Pass Pass I: Longitudinal and lateral ORA should fall below the preferred value of 15.0 g, or at least below the maximum allowed value of 20.49 g. Pass Pass Pass Vehicle Trajectory For redirective devices the vehicle shall exit within the prescribed box. Pass Fail Pass Overall Pass Fail Pass The results reflected outcomes predicted in the simula- tions. The first test was expected to result in a failure due to excessive vehicle roll (and possibly vaulting). In the first test, the vehicle did not impact the barrier at the expected critical impact point just beyond the post because there was less drift than anticipated in traversing the inclined surface. The vehicle followed the rail and was redirected because the early impact with the post kept the rail in an upright position, allowing better capture of the vehicle. The second and third tests impacted the barrier at the computed criti- cal location using the procedure included in MASH and con- firmed the simulation results. In the second test, the simulation accurately predicted (for the tested curvature, superelevation, and shoulder angle) that the vehicle would vault the barrier and not meet MASH criteria for a 1.22-m (4-ft) shoulder. In the third test, the simulation accurately predicted (for the tested curvature, superelevation, and shoulder angle) that the vehicle would get redirected and meet the MASH criteria for a 2.44-m (8-ft) shoulder. Table 6.5. Summary of MASH evaluation of crash test results. 6.8 Conclusions The three full-scale crash tests were conducted at the FOIL located at the FHWA Turner-Fairbank Highway Research Center in McLean, Virginia. The tests were conducted accord- ing to MASH requirements for Test 3-11 involving 2270P vehicles. The evaluation criteria appropriate for longitudi- nal barriers were used as the performance benchmark. An inclined surface was constructed to represent a CSRS with the features of a 254-m (833-ft) radius curve with 6% super- elevation. An asphalt shoulder was installed with a 2Â° decli- nation from the edge of the roadway. The test bed was set up for all barrier placements for shoulder widths of 4 ft and 8 ft. The barrier was placed just at the edge of the shoulder. An appropriate length of G4(1S) longitudinal barrier with end treatments was installed by a certified barrier contractor for each test. The two shoulder widths required that the posi- tioning of the posts consider the prescribed impact points determined to be the most critical. The tests involved launch- ing the vehicle at a speed that allowed it to be at the MASH impact speed when the barrier was reached after traversing the inclined roadway surface and the down sloping shoulder. General Information Test Agency: FOIL Test Number: 16015 Test Date: 08/18/2016 Test Article: G41S W-Beam Guardrail Test Vehicle Description: 2270P Silverado Test Inertial Mass: 2,268 kg Gross Static Mass: 3,085 kg Impact Conditions Speed: 100.0 km/h Angle: 25.0Â° Occupant Risk Factors Impact Velocity (m/s) at 0.2728 s x-direction 4.7 y-direction 4.2 THIV (km/h): 24.3 at 0.2780 s THIV (m/s): 6.8 Ridedown Accelerations (g) x-direction â5.9 (0.3182 to 0.3282 s) y-direction â6.7 (0.2804 to 0.2904 s) PHD (g): 8.8 (0.2805 to 0.2905 s) ASI: 0.60 (0.2014 to 0.2514 s) Max. 50msec Moving Avg. Accelerations (g) x-direction â4.9 (0.2012 to 0.2512 s) y-direction â5.1 (0.3687 to 0.4187 s) z-direction 1.9 (0.5016 to 0.5516 s) Max Roll, Pitch, and Yaw Angles (degrees) Roll â31.6 Pitch â34.5 Yaw 51.3 (0.9998 s) (0.8023 s) (0.9998 s) Table 6.4. Data and results for Test 16015.