Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments (2022)

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54 C H A P T E R 5 5.1 Simulation Suite and Data Collection 5.1.1 Barrier Geometries Barrier configurations were simulated both in accordance with data available for calibration and where there were gaps in preliminary ZOI envelopes. Barrier heights commonly used by state DOTs and those near the maximum barrier height at each test level were simulated. Specifically, vertical, 10.8-degree single-slope, and F-shape concrete barriers were explored with varying heights. Barrier heights and shapes which were evaluated for further study are summarized in Table 21. It was beyond the scope of this study to investigate all barrier variations with similar profiles; when possible, barrier geometries were categorized based on similarities of cross-sectional shapes. For example, low-profile barriers were included under vertical concrete barriers with shorter heights. Most open concrete and steel barriers have vertical faces, so they were also included in verti- cal barrier ZOI envelopes. Jersey barriers were not commonly used at heights above 32 in. and were grouped with F-shape barriers due to their similarities. Note that 24-, 27-, and 29-in. F-shape barrier simulations were not conducted as they were not typically used by state DOTs. For MASH TL-2 and TL-3, only pickup truck (test designation nos. 2-11 and 3-11) ZOI intru- sions were evaluated as small car intrusion was within the ZOI limits of the pickup truck. Pickup truck ZOI intrusions were collected for barriers up to 54-in. tall, but not at every interval evaluated for MASH TL-4 or TL-5 because the ZOI for MASH impact condition 3-11 at 54 in. was negligible. 5.1.2 Barrier Mesh Sizes Three barrier geometries were created for simulation with mesh sizes selected to be consistent with vehicle meshes. For pickup truck simulations, a rigid barrier was defined using 15-mm shell elements such that the contact surface was located at the nominal outer geometry of the barrier. Simulations with the F800 SUT and tractor-trailer model used 30-mm shell elements. Meshes were selected to match the average element size in each respective model to mitigate potential contact instabilities related to mesh size differences. Many model instabilities were encountered in F800 SUT simulations, often related to out-of-range forces and moments. 5.1.3 ZOI Envelope Development The process to collect ZOI data was identical to the process described in Section 4.3. For pickup truck simulations that were used to develop TL-2 and TL-3 ZOIs, five data points were collected, as shown in Figure 43: • Point A: Maximum lateral intrusion of the lowest point on the vehicle to extend in the ZOI. • Point B: Maximum lateral intrusion of the component with the largest ZOI. Simulated ZOI Envelopes

Simulated ZOI Envelopes 55   • Point C: Highest point of vehicle intruding into ZOI at the time of maximum lateral ZOI. • Point D: Highest point above the barrier of any vehicle component during maximum lateral intrusion. • Point E: Highest point above the barrier of any vehicle component measured vertically from the top-front edge of the barrier. For the 10000S Ford F800 SUT and 36000V tractor-trailer models, ZOI data were collected independently for the cab and box/trailer to allow for the unique representation of both zones. Six data points were recorded for each envelope when applicable: two for the cab zone and four for the box/trailer zone, as shown in Figures 44 and 45: • Point A: Maximum lateral intrusion of a stiff cab component. • Point B: Maximum vertical intrusion of a stiff cab component measured vertically from the top-front barrier edge. Table 21. Simulated barrier heights. MASH TL Barrier Height (in.) 24 27 29 32 36 42 48 54 90 2 Xa Xa Xa X X X X 3 Xa X X X X 4 X X X X X 5 X X X X a F-shape barrier simulations were not conducted. A D C B E Figure 43. ZOI envelope data points, 2270P model.

56 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments • Point C: Lowest point of intrusion of the box relative to the top-front barrier edge (when applicable). • Point D: Maximum lateral intrusion of the top-front corner of the box or trailer. • Point E: Maximum lateral intrusion of the top-back corner of the box or trailer. • Point F: Maximum vertical intrusion of the box or trailer measured vertically from the top- front barrier edge. For some simulations, additional measurements were taken to better define the space occu- pied by the cargo box and trailer box components behind the leading top edge of the barrier, similar to the process for ZOI measurement for crash test data. For all data points, both lateral and vertical coordinates of the points corresponding to their measurement times were recorded. A B C D E F Figure 44. ZOI envelope data points, 10000S model.

Simulated ZOI Envelopes 57   5.2 Concepts for Representing ZOI Envelopes 5.2.1 MASH TL-2 and TL-3 After performing the suite of simulations on the barrier profiles and heights for MASH TL-2 and TL-3 impact conditions, as shown in Table 21, the points for developing ZOI envelopes were plotted for each barrier and impact condition evaluated. Three proposed methods for representing the pickup truck ZOI envelope data are shown in Figure 46. The first approach (“detailed” method) segmented the ZOI by contribution: (1) the engine hood, fender, bumper, wheel, and wheel well; and (2) the door frame, roof, and box. The groupings were based on typical ranges of lateral extents and differences between components with large deformations located near the barrier-top surface (i.e., vehicle front end) and smaller defor- mations, lower ZOI intrusions, and ZOI exposure at larger heights (e.g., door, roof, and box). Although more complicated than the original ZOI guidelines presented in the RDG (AASHTO 2011), this approach may allow state DOTs to prioritize the placement of some features within the less critical lower zone without encroaching into the more critical upper zone. Lower and upper zones were created using rectangular representations to be conservative and capture deformations not observed in simulations as well as potential changes in designs of automobiles over time. However, simulation results evaluated using the detailed method were difficult to compare with full-scale testing results because data needed to represent all evaluated zones were not collected in full-scale testing, including a full history of multiple vehicle points and defor- mations throughout impact. A B C D E F Figure 45. ZOI envelope data points, 36000V model.

58 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments The second approach (“piecewise” method) used a simple, piecewise linear connection between the five recorded ZOI points. This method reduced the complexity of representing ZOI envelopes and was reasonably comparable to data gleaned from full-scale crash testing video measurements. The final approach (“conservative” method) simplified ZOI envelope representation to the maximum lateral and vertical extents recorded from simulation. The approach assumed a vehicle could theoretically impact any roadside feature within the boundaries of vertical and horizontal planes corresponding to maximum ZOI points if impact conditions, vehicle geometry, or other factors—including pre-impact factors (e.g., traversing a sidewalk)—modified the vehicle’s ZOI intrusion. Results of the conservative method were easily compared to full-scale test data and historical RDG (AASHTO 2011) recommendations. The conservative method was the simplest to construct based on simulation data, and the detailed method was not likely to be easily compared with full-scale crash test data. However, the conser- vative representation greatly overstated common ZOI intrusions and was likely unnecessarily conservative, imposing limits on the placement of features that were not likely to be contacted in any scenario. The most significant uncertainty associated with comparing simulation results with full-scale testing results according to the detailed method was selecting the proper heights for the ZOI lower boundaries as components with maximum lateral extents did not correspond to the components with highest or lowest vertical extents. Therefore, researchers adopted a ZOI envelope combining the piecewise and detailed rep- resentations (labeled “Detailed” in Figure 47). To generate the proposed envelope, the bottom surface of the vehicle’s encroachment (Point A), the largest lateral encroachment (Point B), and the highest intrusion near the largest lateral encroachment (Point C) were used to define the lower bounds of the ZOI envelope. The upper bounds were defined by the width from Point D 0 10 20 30 40 50 60 70 80 90 0 5 10 15 20 He ig ht A bo ve G ro un d (in .) Lateral Extent (in.) 0 10 20 30 40 50 60 70 80 90 0 5 10 15 20 He ig ht A bo ve G ro un d (in .) Lateral Extent (in.) 0 10 20 30 40 50 60 70 80 90 0 5 10 15 20 He ig ht A bo ve G ro un d (in .) Lateral Extent (in.) Detailed ZOI Piecewise ZOI Conservative ZOI Figure 46. MASH TL-3 ZOI envelope concepts for a 32-in.-tall single-slope barrier.

Simulated ZOI Envelopes 59   and height from Point E, and a linear slope connected the lower and upper ZOI bounds. The proposed MASH 2-11 and 3-11 envelope configuration is shown in Figure 47. Note that these resulting shapes were based on simulation results, which provided significantly more informa- tion than was collected from video analysis of full-scale crash tests. The proposed ZOI envelope was then compared with results from full-scale crash testing to evaluate if the proposed enve- lopes sufficiently captured the important positions of the vehicle extensions over the barrier’s top surface. 5.2.2 MASH TL-4 and TL-5 The methods applied in this section are applicable for both TL-4 and TL-5 applications. For simplicity, only TL-4 recommendations are shown, but similar procedures were used for both TL-4 and TL-5 envelopes for the cab and box/trailer ZOIs, as shown in Figure 48. The piece- wise method used linear segments connecting each data point gathered from simulations. The conservative method represented the ZOI based on the maximum values of the lateral and ver- tical extensions and was consistent with the technique used in the RDG (AASHTO 2011). In general, the piecewise method most accurately described box intrusion but underestimated cab intrusion. The proposed ZOI envelope utilized a combination of the conservative representation of the cab zone and a piecewise representation of the box or trailer zone. This approach ensured that 0 10 20 30 40 50 60 70 80 90 0 10 20 He ig ht A bo ve G ro un d (in .) Lateral Extent (in.) Detailed ZOI 0 10 20 30 40 50 60 70 80 90 0 10 20 He ig ht A bo ve G ro un d (in .) Lateral Extent (in.) Preliminary ZOI Envelope Figure 47. Proposed MASH TL-3 ZOI envelope for a 32-in.-tall single-slope barrier.

60 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments the cab intrusion, which varied significantly, would be conservatively evaluated for the potential for impact with roadside features. The simulated cab model is older, and it is uncertain if the cab zone predicted in the simulation is consistent with the cab intrusion for modern vehicles, as dis- cussed in Section 8.8.1. To avoid the potential for loss of life for occupants of an SUT or tractor vehicle, a conservative cab zone was warranted. However, most, if not all tractor-trailer and SUT impacts will not extend outside of the regions defined for the box or trailer zones, respectively, and thus an overly conservative box or trailer zone was not deemed necessary. 5.3 ZOI Envelope Simulation Results 5.3.1 MASH TL-2 Eighteen MASH TL-2 simulations were analyzed and used to develop ZOI envelopes. ZOI envelopes are shown for all heights (above barriers) in Figure 49, by barrier height in Figures 50 through 56, and by barrier shape in Figures 57 through 59. Although vertical barriers produced the maximum lateral extent for all barrier heights, the difference was not significant by barrier shape. A 2.1-in. maximum difference in lateral extent was observed when comparing barrier shapes at a 36-in. height. Lateral extent decreased as bar- rier height increased, from a maximum of 15.8 in. for the 24-in.-tall vertical barrier to 0.0 in. for the 54-in.-tall F-shape and single-slope barriers. F-shape barriers were associated with the largest vertical displacements of impacting vehicle and tallest ZOI envelopes. However, at 24-, 27-, and 29-in. barrier heights where F-shape simu- lations were not conducted, vertical barriers were associated with the highest vertical extent. An 8.9-in. maximum difference in vertical intrusion was observed when comparing barrier Figure 48. Proposed MASH TL-4 ZOI envelope for a 32-in.-tall single-slope barrier.

Simulated ZOI Envelopes 61   Figure 49. MASH TL-2 simulation ZOI envelopes, all barriers and heights. Figure 50. MASH TL-2 simulation ZOI envelopes, 24-in.-tall barriers.

62 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 51. MASH TL-2 simulation ZOI envelopes, 27-in.-tall barriers. Figure 52. MASH TL-2 simulation ZOI envelopes, 29-in.-tall barriers.

Simulated ZOI Envelopes 63   Figure 53. MASH TL-2 simulation ZOI envelopes, 32-in.-tall barriers. Figure 54. MASH TL-2 simulation ZOI envelopes, 36-in.-tall barriers.

64 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 55. MASH TL-2 simulation ZOI envelopes, 42-in.-tall barriers. Figure 56. MASH TL-2 simulation ZOI envelopes, 54-in.-tall barriers.

Simulated ZOI Envelopes 65   Figure 57. MASH TL-2 simulation ZOI envelopes, vertical barriers.

66 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 58. MASH TL-2 simulation ZOI envelopes, single-slope barriers.

Simulated ZOI Envelopes 67   shapes at a 27-in. height. Vertical extent decreased as the vertical barrier height increased from a maximum of 65.3 in. for the 24- and 27-in.-tall single-slope simulation to 0.0 in. for the 54-in.-tall F-shape and single-slope barriers. Envelopes became more rectangular as barrier height increased and were entirely rectangular at barrier heights greater than or equal to 42 in. Surprisingly, single-slope barriers were associated with the lowest vertical extents of the barrier shapes evaluated. The reduced vertical extent indicates that the simulated vehicles did not climb the barrier during impact. Results also suggest that the angled impact surface reduced vehicle roll on top of the barrier during impact by aligning more of the impact force with the vehicle’s c.g. 5.3.2 MASH TL-3 Fourteen MASH TL-3 simulations were analyzed and used to develop ZOI envelopes. ZOI enve- lopes are shown for all barriers and heights in Figure 60, by barrier height in Figures 61 through 65, and by barrier shape in Figures 66 through 68. Vertical barriers typically produced the maximum lateral extent for all barrier heights, but differences were not significant by barrier shape. A 2.3-in. maximum difference in lateral extent was observed for different barrier shapes at a 36-in. height. Lateral extent decreased as barrier height increased, from a maximum of 16.9 in. for the 29-in.-tall vertical barrier to a nearly unmeasurable value of 0.1 in. for the 54-in.-tall vertical barrier. Figure 59. MASH TL-2 simulation ZOI envelopes, F-shape barriers.

68 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 60. MASH TL-3 simulation ZOI envelopes, all barriers and heights. Figure 61. MASH TL-3 simulation ZOI envelopes, 29-in.-tall barriers.

Simulated ZOI Envelopes 69   Figure 62. MASH TL-3 simulation ZOI envelopes, 32-in.-tall barriers. Figure 63. MASH TL-3 simulation ZOI envelopes, 36-in.-tall barriers.

70 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 64. MASH TL-3 simulation ZOI envelopes, 42-in.-tall barriers. Figure 65. MASH TL-3 simulation ZOI envelopes, 54-in.-tall barriers.

Simulated ZOI Envelopes 71   Figure 66. MASH TL-3 simulation ZOI envelopes, vertical barriers.

72 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 67. MASH TL-3 simulation ZOI envelopes, single-slope barriers.

Simulated ZOI Envelopes 73   Figure 68. MASH TL-3 simulation ZOI envelopes, F-shape barriers. Although single-slope barriers typically achieved the maximum vertical extent, the difference was not significant by barrier shape. A 4.8-in. maximum difference in vertical intrusion was observed when comparing barrier shapes at a 36-in. height. This trend varied from the results observed at TL-2 impact conditions. Vertical extent decreased as barrier height increased, from a maximum of 76.9 in. for the 32-in.-tall single-slope barrier to a minimum of 55.4 in. for the 54-in.-tall vertical barrier. The recommended shapes of ZOI envelopes collapsed to a rectangle at 42-in. barrier heights. No door, roof, or box intrusion occurred for barriers taller than 42 in., and ZOI was primarily limited to hood and quarter panel intrusion. 5.3.3 MASH TL-4 MASH TL-4 simulations were analyzed and used to develop ZOI envelopes. ZOI envelopes are shown by barrier shape and height in Figures 69 through 73, barrier shape in Figures 74 through 76 for the cab, and barrier shape in Figures 77 through 79 for the box. The cab zone was conservatively defined to include the maximum lateral extents and heights of the cab intruding past the top traffic-side barrier edge. The lateral cab zone was the largest for F-shape barriers and the lowest for single-slope barriers. Lateral cab intrusion ranged between 9.2 in. and 26.1 in. for 36-in.-tall barriers (Figure 69) and 0.6 in. and 15.0 in. for 42-in.-tall barriers (Figure 70). No cab intrusion occurred for barrier heights greater than or equal to 48 in (Figure 71).

74 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 69. MASH TL-4 ZOI simulation envelopes, 36-in.-tall barriers.

Simulated ZOI Envelopes 75   Figure 70. MASH TL-4 ZOI simulation envelopes, 42-in.-tall barriers.

76 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 71. MASH TL-4 ZOI simulation envelopes, 48-in.-tall barriers.

Simulated ZOI Envelopes 77   Figure 72. MASH TL-4 ZOI simulation envelopes, 54-in.-tall barriers.

78 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 73. MASH TL-4 ZOI simulation envelopes, 90-in.-tall barriers.

Simulated ZOI Envelopes 79   Figure 74. MASH TL-4 cab ZOI simulation envelopes, vertical barriers.

80 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 75. MASH TL-4 cab ZOI simulation envelopes, single-slope barriers.

Simulated ZOI Envelopes 81   Figure 76. MASH TL-4 cab ZOI simulation envelopes, F-shape barriers.

82 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 77. MASH TL-4 box ZOI simulation envelopes, vertical barriers.

Simulated ZOI Envelopes 83   Figure 78. MASH TL-4 box ZOI simulation envelopes, single-slope barriers.

84 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 79. MASH TL-4 box ZOI simulation envelopes, F-shape barriers. The 10000S vehicle extended over the barrier-top surface for every height. The largest lateral intrusion was associated with F-shape barriers for every height. Maximum lateral box extents were 76.4 in., 59.1 in., 22.3 in., 29.0 in., and 13.1 in., and maximum vertical extents were 164.9 in., 153.9 in., 136.2 in., 137.5 in., and 135.0 in. for barrier-top heights of 36 in., 42 in., 48 in., 54 in., and 90 in., respectively. It was noted that the F-shape barrier produced a larger lateral and verti- cal extension for the SUT vehicle at 54 in. than was observed with 48 in. and did not match the general trend of declining lateral extent with increased barrier height. This anomaly resulted from the top edge of the box extending over the barrier-top surface and causing the box to pivot upward and laterally. A careful review of the results of the TL-4 simulation did not reveal any modeling inconsistencies, numerical errors, or circumstances that would suggest that results were unobtainable, even though they were not consistent with the general trend. 5.3.4 MASH TL-5 MASH TL-5 simulations were analyzed and used to develop ZOI envelopes. ZOI envelopes are shown by barrier height in Figures 80 through 83 and by barrier shape in Figures 84 through 86 for the cab and Figures 87 through 89 for the trailer. The maximum lateral extent of the cab was 13.3 in for 42-in.-tall single-slope barriers; this was the only barrier shape and height combination at which the cab extended past the nominal

Simulated ZOI Envelopes 85   Figure 80. MASH TL-5 ZOI simulation envelopes, 42-in.-tall barriers.

86 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 81. MASH TL-5 ZOI simulation envelopes, 48-in.-tall barriers.

Simulated ZOI Envelopes 87   Figure 82. MASH TL-5 ZOI simulation envelopes, 54-in.-tall barriers.

88 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 83. MASH TL-5 ZOI simulation envelopes, 90-in.-tall barriers.

Simulated ZOI Envelopes 89   Figure 84. MASH TL-5 cab ZOI simulation envelopes, vertical barriers.

90 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 85. MASH TL-5 cab ZOI simulation envelopes, single-slope barriers.

Simulated ZOI Envelopes 91   Figure 86. MASH TL-5 cab ZOI simulation envelopes, F-shape.

92 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 87. MASH TL-5 trailer ZOI simulation envelopes, vertical barriers.

Simulated ZOI Envelopes 93   Figure 88. MASH TL-5 trailer ZOI simulation envelopes, single-slope barriers.

94 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 89. MASH TL-5 trailer ZOI simulation envelopes, F-shape barriers. barrier width. Single-slope barriers 42-in.-tall also displayed the maximum height above ground, at 113.4 in. However, cab vertical extent was comparable among all barrier shapes and heights. The maximum lateral extent of the box was 71.4 in. for 42-in.-tall single-slope barriers. Lateral encroachment decreased significantly from 42- to 48-in. barriers; when averaged across the three barrier types, maximum lateral extent of the box for 48-in.-tall barriers was 64.3% lower than for 42-in.-tall barriers. Returns diminished thereafter as maximum lateral extents were very similar for 48- and 54-in.-tall barriers. Similar trends were observed for vertical extent, which significantly decreased as barrier height increased from 42 in. to 48 in. and remained near the nominal height of the box for barriers taller than 48 in. Maximum height above ground was 184.7 in. for 42-in.-tall single-slope barriers. 5.4 Validation of ZOI Envelopes 5.4.1 Overview Researchers merged the simulation and full-scale crash test database to ensure the proposed ZOI envelope updates represented realistic boundaries for vehicle intrusions. Additionally, researchers sought to identify patterns based on barrier height, geometry, and impact conditions

Simulated ZOI Envelopes 95   to simplify ZOI recommendations for inclusion in an RDG update. Emphasis was placed on MASH test results; MASH has been the accepted standard for performing crash testing for the last decade, and the number of vehicles that are well-represented by crash test vehicles used in testing performed according to NCHRP Report 350 (Ross et al. 1993) and the AASHTO Guide Specifications for Bridge Rails (AASHTO 1989) are waning. Nonetheless, for FEA model calibration, some ZOI data from tests performed in accordance with NCHRP Report 350 were included, particularly those used to develop initial recommendations for RDG ZOI envelopes (Keller et al. 2003). Results were plotted together for barrier geometries and separately for barrier shapes using the top traffic-side barrier edge as a reference point and referenced against the road surface (true ZOI envelope heights). MASH tests and simulations were compared, and expanded reviews of MASH, NCHRP Report 350 (Ross et al. 1993), simulation, and RDG (AASHTO 2011) results were conducted. Vertical barrier simulations were compared to full-scale crash test data from vertical barriers and combination rails as well as the RDG (AASHTO 2011). Combination rails were included as they tended to have vertical profiles; these systems typically encompassed steel tubular, steel combination, concrete combination, timber rails, and any variation of these rails combined with curbs. Although some combination rails had cross-sectional geometries with sloped front faces, they also included vertical sections expected to cause similar vehicle behavior as vertical barriers. Simulations from the review in Section 2.4 and the barrier configurations simulated in Sec- tion 5.1 were compiled to form ZOI envelopes. ZOI values for F-shape, single-slope, and vertical barriers were identified within the range of barrier height thresholds for TL-2, TL-3, TL-4, and TL-5. There were two key relationships to understand in this project: the relationships between barrier height and shape with ZOI. An in-depth examination was conducted on intrusion data compared to barrier height to discover this relationship. This study included traffic barriers with relatively wide barrier height thresholds. ZOI envelopes were created using a full-scale crash test and validated simulation data, and the envelopes were considered validated. Additionally, the research team used available existing crash test data from impacts with attachments or other objects placed on top of or adjacent to rigid barriers to further validate the envelopes. ISPE data were used to correlate attachment or object impact with injuries, although data were minimal. MwRSF’s past ZOI studies of rigid barrier shapes impacted by a 2000P vehicle under NCHRP Report 350 standards (Ross et al. 1993) revealed that while F-shape and Jersey barriers have very similar profiles, the ZOI was significantly larger for New Jersey shape barriers. The primary difference between the two barriers was the lower sloped face of the Jersey barrier was 3 in. taller than the F-shape barrier. The toe height may have contributed to additional vehicle climb, which can likewise contribute to higher roll and pitch angles when the vehicle’s front fender impacts the upper sloped face of the barrier and may also affect vehicle deformations by extending the impact and decreasing the peak force. The vertical barrier was expected to have the highest vehicle deformation and impart the largest lateral forces, as the vertical barrier does not transmit the vehicle’s lateral energy into vertical motion nor apply a large rolling moment to increase the vehicle’s roll energy. Therefore, a more detailed investigation was conducted to determine the effects of barrier shapes on ZOI. The current ZOI envelopes included in the RDG for TL-3 impacts were developed based solely on lateral intrusion of the vehicle over the top of the barrier (AASHTO 2011). Thus, the TL-3 ZOI envelopes were all rectangular. However, the extent of lateral vehicle intrusion was expected to differ based on vertical location. Generally, major vehicle intrusion occurs near the top of the barrier, and lateral extension subsides as distance above the barrier increases. As such,

96 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments larger and more conservative ZOI envelopes are currently recommended. Researchers proposed to develop the ZOI envelopes considering both lateral and vertical vehicle intrusion. These enve- lopes more accurately depict vehicle intrusions and allow roadside objects like sign supports to be placed closer to the roadway. Finally, it is important to note that crash tests shown in this report reflect the state of avail- able information at a snapshot in time, and as further information arises, changes to the ZOI envelopes may be warranted. Updates to results may be evaluated as additional full-scale crash tests occur and as time accrues following the completion of this project. 5.4.2 MASH TL-2 MASH TL-2 ZOIs from simulation and full-scale crash tests are compared in Figures 90 through 94. Note that no full-scale crash tests were conducted under MASH TL-2 criteria on 27- or 29-in.-tall barriers. For barriers between 24 in. and 27 in. tall, the simulations were non-conservative, and test data indicated a higher lateral ZOI extension. However, test no. IBBR-1 was unique; the bar- rier system consisted of a shorter, 24-in.-tall concrete parapet with a thin tubular steel hand- rail supported on tall, tubular steel posts. The upper rail system was not structurally strong enough to significantly contribute to the vehicle’s redirection. The maximum lateral extension recorded in the test occurred after the impacting front quarter panel snagged on a vertical post and deformed laterally. Thus, this test was not believed to be representative of 24-in.-tall barrier systems in general. For test no. 469469-3-2, the barrier system was only 20 in. tall and therefore was located slightly outside of the studied barrier range, and the maximum lateral extent of the Figure 90. MASH TL-2 ZOI envelope validation, 24- to 27-in.-tall barriers.

Simulated ZOI Envelopes 97   Figure 91. MASH TL-2 ZOI envelope validation, 27- to 29-in.-tall barriers. Figure 92. MASH TL-2 ZOI envelope validation, 29-in. to 32-in.-tall barriers.

98 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 93. MASH TL-2 ZOI envelope validation, 32-in. to 42-in.-tall barriers. Figure 94. MASH TL-2 ZOI envelope validation, 42-in. or taller barriers.

Simulated ZOI Envelopes 99   vehicle’s impacting front quarter panel was approximately 16 in., which was 1 in. larger than the simulation data. Limited test data were available for the majority of the simulated barrier shapes and heights at MASH TL-2 impact conditions. In general, although simulations provided a reasonable esti- mate of the maximum lateral extension, test data were often larger than simulation data. The heights of the RDG windows were much taller than the majority of test and simulation data, except the 20-in.-tall barrier evaluated in test no. 469469-3-2 (AASHTO 2011). Simulated data accurately captured the maximum vertical extents of the vehicles during full-scale crash tests. Results of all full-scale crash tests and simulations were compared by plotting the barrier-top height against the maximum lateral extension of the vehicle. Results of the overplot are shown in Figure 95. It was observed that, except for test results used when determining the original RDG NOTE: Test no. IBBR-1 utilized a concrete parapet measuring 24 in. tall with an additional handrail on top. Fender contact with the handrail caused the fender to protrude laterally, whereas other 24-in.-tall-vertical parapets without top-mounted handrails have not produced similar lateral extensions. Therefore, this ZOI is not believed to be consistent with other 24-in.-tall-vertical parapet shapes. Figure 95. Comparison of full-scale crash test data and computer simulation results for MASH TL-2 impact conditions.

100 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments guidelines for ZOI envelopes, the MASH TL-2 full-scale crash test and simulation results were well-bounded by a lateral extent trend line, as shown in Figure 95. Few full-scale crash tests were located at larger lateral offsets than the observed trend line. The three tests that were not included within the trend line included two tests used in the development of the RDG guidelines in 2003, involving vehicles with production years before 2000 (AASHTO 2011), and test no. IBBR-1, which involved a fourth-generation RAM pickup truck impacting a 24-in.-tall, vertical concrete parapet with a bicycle railing mounted on top. During test no. IBBR-1, the test vehicle’s impacting front quarter panel contacted a vertical post and deformed laterally toward the back side of the system. This extension into the ZOI was estimated using high-speed video and was included in the estimated maximum lateral intrusion of the system. However, the upper bicycle railing was not believed to significantly contribute to the vehicle’s redirection. If the bicycle rail was excluded, the maximum lateral intrusion of the vehicle’s stiff component would have likely been significantly lower. The BDS (AASHTO 2017) provides guidelines for bicycle and pedestrian railings that limit the size of spaces in the rail through which a pedestrian or bicyclist could protrude; the Iowa design was intended for a spe- cific application that was different from BDS specifications. Therefore, the lateral extent of test no. IBBR-1 was not considered when developing the practical, conservative ZOI envelope rec- ommendations. Researchers, therefore, utilized the trend line and conservative extrapolations of results to generate recommendations for the shape of the ZOI envelope. The conservative extrapolations from the trend line are shown in Figure 96, and recommended ZOI envelopes for TL-2 shapes are summarized in Chapter 6. 5.4.3 MASH TL-3 MASH TL-3 ZOIs from simulation and full-scale crash tests are compared in Figures 97 through 100. Significant differences were observed between crash tests used to estimate the ZOI enve- lopes for the RDG (AASHTO 2011) compared to full-scale crash tests performed to MASH TL-3. Many data points were available to evaluate ranges of barrier heights according to MASH 3-11 impact conditions for barrier heights of 32 in., 36 in., and 42 in. Simulation results were larger than values reported or measured using high-speed video analysis in approximately 90% of MASH full-scale crash tests. Even for crash tests with ZOIs larger than the simulated enve- lopes, results were usually within 5% of the simulation values. Maximum vertical extensions of the vehicle at the barrier face were well-represented by simulation data for most barrier and crash test configurations considered. Results of all full-scale crash tests and simulations were compared by plotting the barrier-top height against the maximum lateral extension of the vehicle. Results of the overplot are shown in Figure 101. It was observed that, except for test results used when determining the original RDG guidelines for ZOI envelopes (AASHTO 2011), the MASH TL-3 full-scale crash test and simulation results were well-bounded by a lateral extent trend line, as shown in Figure 101. Researchers, therefore, utilized the trend line and conservative extrapolations of results to gen- erate recommendations for the shape of the ZOI envelope. The conservative extrapolations from the trend line are shown in Figure 102, and recommended ZOI envelopes for TL-3 shapes are summarized in Chapter 6. 5.4.4 MASH TL-4 MASH TL-4 ZOIs from simulations and full-scale crash tests are compared in Figures 103 through 106. Cab extensions into the ZOI are shown in Figures 103 and 104. As noted, the struc- turally stiff parts of the cab included the hood, upper steel body components, door frame, wind- shield, bumper, grille, frame, and door step. Weaker components of the cab were not included in

NOTE: Test no. IBBR-1 utilized a concrete parapet measuring 24 in. tall with an additional handrail on top. Fender contact with the handrail caused the fender to protrude laterally, whereas other 24-in.-tall vertical parapets without top-mounted handrails have not produced similar lateral extensions. Therefore, this ZOI is not believed to be consistent with other 24-in.-tall vertical parapet shapes. Figure 96. Proposed lateral extents of ZOI envelopes for MASH TL-2 impact conditions.

Figure 97. MASH TL-3 ZOI envelope validation, 30-in. to 34-in.-tall barriers. Figure 98. MASH TL-3 ZOI envelope validation, 34-in. to 42-in.-tall barriers.

Single Slope Steel & Combination Simulation Figure 99. MASH TL-3 ZOI envelope validation, 42-in. to 54-in.-tall barriers. Figure 100. MASH TL-3 ZOI envelope validation, 54-in. or taller barriers.

29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 0 2 4 6 8 10 12 14 16 18 20 22 24 B ar rie r H ei gh t ( in .) Maximum Lateral Extension (in.) Lateral Extent Comparison: Simulations, MASH 2016 Crash Tests, Roadside Design Guide Crash Tests Simulation F-Shape Simulation Single-slope Simulation Vertical Barrier (Single-slope) 2270P Simulation (F-shape) NJPCB-2 (F-shape) 476460-1-4 (F-shape) 466462-1 (F-shape) 466462-2 (F-shape) MNPD-3 (Single-slope) OSSB-1 (Single-slope) 140MASH3C16-04 (Single-slope) 405160-13-1 (Single-slope) 420020-3 (Vertical) 490024-2-1 (Vertical) 475350-1 (Vertical) 420021-5 (Vertical) H34BR-2 (Vertical) KSFRP-1 (Other or Transitions) SFH-2 (Other or Transitions) 34AGT-2 (Other or Transitions) AGTB-2 (Other or Transitions) TCBT-1 (Other or Transitions) 34AGT-1 (Steel Rail) 420021-2 (Steel Rail) 490026-4-1 (Steel Rail) 490022-1 (Steel Rail) STBR-2 (Steel Rail) 130MASH3P13-01 (Steel Rail) 690900-GEC2 (Steel Rail) 690900-GEC3 (Steel Rail) 690900-GEC9 (Steel Rail) 6083311-01-2 (Steel Rail) 110MASH3P15-01 (Steel Rail) 110MASH4P18-01 (Steel Rail) 110MASH4P18-02 (Steel Rail) NCBR-2 (Steel Rail) MNCBR-2 (Steel Rail) 469468-1-2 (Steel Rail) 469469-2-1 (Steel Rail) 607841-2 (Other or Transitions) 469469-5 (Single-slope) 469689-2-2 (Steel Rail) NCBR-2-30 in. RDG Nebraska Open Concrete Rail 1 RDG Nebraska Open Concrete Rail 2 RDG New Jersey Safety Shape RDG Texas Type T411 Bridge Rail RDG 32-in. Vertical Wall RDG New Jersey Safety Shape RDG New Jersey Safety Shape RDG F-shape RDG Single-slope RDG Illinois Side-Mount Bridge Rail RDG Illinois 2399 Bridge Rail RDG NETC Bridge Rail RDG Wood Bridge Rail RDG- Minnesota Comb. Bridge Rail RDG Steel Rail for Transverse Decks RDG BR27C Bridge Rail on Deck Trendline Lateral Extent Trend Line Figure 101. Comparison of full-scale crash test data and computer simulation results for MASH TL-3 impact conditions.

29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 0 2 4 6 8 10 12 14 16 18 20 22 24 B ar rie rH ei gh t ( in .) Maximum Lateral Extension (in.) Proposed Lateral Extents of ZOI Envelopes for MASH TL-3 Impact Conditions Simulation F-Shape Simulation Single-slope Simulation Vertical Barrier (Single-slope) 2270P Simulation (F-shape) NJPCB-2 (F-shape) 476460-1-4 (F-shape) 466462-1 (F-shape) 466462-2 (F-shape) MNPD-3 (Single-slope) OSSB-1 (Single-slope) 140MASH3C16-04 (Single-slope) 405160-13-1 (Single-slope) 420020-3 (Vertical) 490024-2-1 (Vertical) 475350-1 (Vertical) 420021-5 (Vertical) H34BR-2 (Vertical) KSFRP-1 (Other or Transitions) SFH-2 (Other or Transitions) 34AGT-2 (Other or Transitions) AGTB-2 (Other or Transitions) TCBT-1 (Other or Transitions) 34AGT-1 (Steel Rail) 420021-2 (Steel Rail) 490026-4-1 (Steel Rail) 490022-1 (Steel Rail) STBR-2 (Steel Rail) 130MASH3P13-01 (Steel Rail) 690900-GEC2 (Steel Rail) 690900-GEC3 (Steel Rail) 690900-GEC9 (Steel Rail) 6083311-01-2 (Steel Rail) 110MASH3P15-01 (Steel Rail) 110MASH4P18-01 (Steel Rail) 110MASH4P18-02 (Steel Rail) NCBR-2 (Steel Rail) MNCBR-2 (Steel Rail) 469468-1-2 (Steel Rail) 469469-2-1 (Steel Rail) 607841-2 (Other or Transitions) 469469-5 (Single-slope) 469689-2-2 (Steel Rail) NCBR-2-30in. RDG Nebraska Open Concrete Rail 1 RDG Nebraska Open Concrete Rail 2 RDG New Jersey Safety Shape RDG Texas Type T411 Bridge Rail RDG 32-in. Vertical Wall RDG New Jersey Safety Shape RDG New Jersey Safety Shape RDG F-shape RDG Single-slope RDG Illinois Side-Mount Bridge Rail RDG Illinois 2399 Bridge Rail RDG NETC Bridge Rail RDG Wood Bridge Rail RDG- Minnesota Comb. Bridge Rail RDG Steel Rail for Transverse Decks RDG BR27C Bridge Rail on Deck Lateral Extent Trend Line Recommended Lateral ZOI Limits RDG for Other TL- 3 Barriers RDG for Other Sloped-Face & Steel Tube Barriers Figure 102. Proposed lateral extents of ZOI envelopes for MASH TL-3 impact conditions.

106 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 104. MASH TL-4 cab ZOI envelope validation, 42-in-tall barriers. Figure 103. MASH TL-4 cab ZOI envelope validation, 36-in.-tall barriers.

Simulated ZOI Envelopes 107   Figure 105. MASH TL-4 box ZOI envelope comparison, 36-in. to 42-in.-tall barriers.

108 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments ZOI data collection, including mirrors, fiberglass body panel components, and vertical exhaust members. Due to the potential for serious injury or death to occur if the structurally stiff parts of the cab impacted a structurally stiff element located behind the barrier system, a conservative cab zone was defined, as noted in Section 5.2.2. Thus, all comparisons of full-scale crash test and simulation data utilized rectangular representations of the vehicle cab. Computer simulations represented approximately the average of full-scale crash test data collected for the cab extension into the ZOI past the top, traffic-side edge of the barrier. Results indicate that despite significant effort expended to improve the accuracy of the SUT simulation model, more research and modeling development are needed to capture the accurate behavior of the cab during the initial time after impact. Lateral box extensions of the computer simulation models and full-scale tests are compared in Figures 105 and 106. Computer simulation reasonably predicted the maximum lateral extension of the box past the barrier. Vertical extents of the box varied widely in test data, and computer simula- tion captured more than half of the vertical ZOI extents recorded from full-scale crash test data. As noted in the discussion of the TL-4 simulation results, the simulation performed in accor- dance with MASH TL-4 impact conditions with the 54-in.-tall, F-shape barrier did not follow Figure 106. MASH TL-4 box ZOI envelope validation, 42-in. or taller barriers.

Simulated ZOI Envelopes 109   the expected trend. The computer simulation model inputs and results were reviewed, and errors that would adversely influence vehicle behavior were not observed. Nonetheless, in recognition that computer simulation models were limited and real-world extensions of the vehicle over the top of the barrier may be larger than the models predicted, the research team selected a trend line for F-shape barriers that incorporated the larger offset at 54 in. Further research may be necessary to determine an empirical ZOI intrusion value for F-shape barriers at a 54-in.-barrier-top height if the proposed value is deemed too conservative. Results of all full-scale crash tests and simulations were compared by plotting the barrier-top height against the maximum lateral extension of the vehicle. Results of the cab overplot are shown in Figure 107, and results of the box overplot are shown in Figure 108. It was observed that for cab and box ZOI extensions, simulations of F-shape barriers had the highest ZOI values and better captured the limits of full-scale test data. Because no simulations indicated any positive ZOI for the cab zone for barriers with a height of 48 in. or above, the results from the 42-in.-tall full-scale crash tests and 48-in.-tall simulations were linearly interpolated to estimate the effect of barrier height on the cab zone. The interpolated trend line and full-scale crash data were used to generate recommended ZOI envelope sizes, as shown in Figure 109. Although few F-shape barrier tests were available for TL-4 simulations, researchers utilized the F-shape barrier simulation results to define the recommended ZOI envelope data for the box zones, as shown in Figure 110. The resulting recommended ZOI envelopes for TL-4 shapes are summarized in Chapter 6. 5.4.5 MASH TL-5 MASH TL-5 ZOIs from simulations and full-scale crash tests are compared in Figures 111 through 113. As noted previously, because the cab zone is associated with a significantly increased Figure 107. Comparison of cab ZOI intrusion results for MASH TL-4 impact conditions: full-scale crash test data and computer simulations. 34 36 38 40 42 44 46 48 0 5 10 15 20 25 30 35 40 Ba rr ie r he ig ht (i n. ) Maximum extent (in.) MASH TL-4 Cab ZOI Intrusions (F-shape) Simulation (Single-slope) Simulation (Single-slope) 420020-9b (Single-slope) 469680-2-1 (Single-slope) 469680-2-2 (Single-slope) 469680-2-3 (Single-slope) 4CBR-1 (Single-slope) 510602-EWP1 (Single-slope) 469467-3-1 (Single-slope) 469468-6-1 (Single-slope) 490027-2-1 (Vertical) Simulation (Vertical) 469467-1-1 (Steel rail) 110MASH4S19-04 (Steel rail) 110MASH4S19-02 (Steel rail) 60831-1-1 (Steel rail) MNCBR-1 (Steel rail) STBR-4 (Steel rail) 110MASH4S16-03 (Steel rail) 496468-1-3 (Steel rail) 490026-4-3 RDG - CSC2 RDG - CSC1 RDG - TC2 Lateral Extent Trend Line

110 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Ba rr ie rh ei gh t ( in .) Maximum extent (in.) Proposed MASH TL-4 Box ZOI Envelope Ranges (F-shape) Simulation (Single-slope) Simulation (Single-slope) 420020-9b (Single-slope) 469680-2-1 (Single-slope) 469680-2-3 (Single-slope) 4CBR-1 (Single-slope) 510602-EWP1 (Single-slope) 469467-3-1 (Single-slope) 469468-6-1 (Single-slope) 490027-2-1 (Vertical) Simulation (Vertical) 469467-1-1 (Steel rail) 110MASH4S19-04 (Steel rail) 110MASH4S19-02 (Steel rail) 60831-1-1 (Steel rail) MNCBR-1 (Steel rail) STBR-4 (Steel rail) 110MASH4S16-03 (Steel rail) 490026-4-3 RDG- T4 RDG - CSC1 RDG - TC2 Lateral Extent Trend Line Figure 108. Comparison of box ZOI intrusion results for MASH TL-4 impact conditions: full-scale crash test data and computer simulations. 34 36 38 40 42 44 46 48 0 5 10 15 20 25 30 35 40 Ba rr ie r he ig ht (i n. ) Maximum extent (in.) Proposed MASH TL-4 Cab ZOI Envelope Ranges (F-shape) Simulation (Single-slope) Simulation (Single-slope) 420020-9b (Single-slope) 469680-2-1 (Single-slope) 469680-2-2 (Single-slope) 469680-2-3 (Single-slope) 4CBR-1 (Single-slope) 510602-EWP1 (Single-slope) 469467-3-1 (Single-slope) 469468-6-1 (Single-slope) 490027-2-1 (Vertical) Simulation (Vertical) 469467-1-1 (Steel rail) 110MASH4S19-04 (Steel rail) 110MASH4S19-02 (Steel rail) 60831-1-1 (Steel rail) MNCBR-1 (Steel rail) STBR-4 (Steel rail) 110MASH4S16-03 (Steel rail) 496468-1-3 (Steel rail) 490026-4-3 RDG - CSC2 RDG - CSC1 RDG - TC2 Lateral Extent Trend Line RDG Trailer Envelope Recommended Lateral ZOI Limits Figure 109. Proposed cab zone lateral extents of ZOI envelopes for MASH TL-4 impact conditions.

30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Ba rr ie rh ei gh t ( in .) Maximum extent (in.) (F-shape) Simulation (Single-slope) Simulation (Single-slope) 420020-9b (Single-slope) 469680-2-1 (Single-slope) 469680-2-3 (Single-slope) 4CBR-1 (Single-slope) 510602-EWP1 (Single-slope) 469467-3-1 (Single-slope) 469468-6-1 (Single-slope) 490027-2-1 (Vertical) Simulation (Vertical) 469467-1-1 (Steel rail) 110MASH4S19-04 (Steel rail) 110MASH4S19-02 (Steel rail) 60831-1-1 (Steel rail) MNCBR-1 (Steel rail) STBR-4 (Steel rail) 110MASH4S16-03 (Steel rail) 490026-4-3 RDG- T4 RDG - CSC1 RDG - TC2 Proposed MASH TL-4 Box ZOI Envelope Ranges Lateral Extent Trend Line Recommended Lateral ZOI Limits RDG Trailer Recommendations Figure 110. Proposed lateral box zone extents of ZOI envelopes for MASH TL-4 impact conditions. Figure 111. MASH TL-5 cab ZOI envelope validation, 42-in.-tall barriers.

Figure 113. MASH TL-5 cab ZOI envelope validation, 54-in.-tall barriers. Figure 112. MASH TL-5 cab ZOI envelope validation, 48-in.-tall barriers.

Simulated ZOI Envelopes 113   risk for severe injury or fatality if a stiff component of the cab contacts a stiff feature located above or behind the barrier, a conservative rectangular cab zone was used to evaluate all test and simulation data. Cab zones were vanishingly small for 54-in.-tall barriers. Comparisons of simulated trailer zones and results from full-scale crash tests are shown in Figures 114 through 116. Results of MASH TL-5 trailer zones varied significantly, and no clear trends were observed related to barrier profile. Because test vehicles, weights, and impact con- ditions for tests conducted according to MASH TL-5 test designation no. 5-11 were consistent with NCHRP Report 350 test designation no. 5-11 (Ross et al. 1993), results from both MASH and NCHRP Report 350 were included. In general, single-slope simulations were associated with larger trailer zone ZOIs than verti- cal or F-shape barriers. The single-slope simulations also were similar to or slightly exceeded the recorded full-scale crash test data. With the exception of the 42-in.-barrier-top height, few barrier heights had significant full-scale crash test data, and no barrier geometry had significant data with which to compare the computer simulation results. Therefore, researchers recom- mended conservative ZOI envelopes for both the cab and trailer zones, which encapsulated full- scale crash test and simulation data. Distinctions were not made by barrier shape at this time. Figure 114. MASH TL-5 trailer ZOI envelope validation, 42-in.-tall barriers.

Figure 116. MASH TL-5 trailer ZOI envelope validation, 54-in.-tall barriers. Figure 115. MASH TL-5 trailer ZOI envelope validation, 48-in.-tall barriers.

Simulated ZOI Envelopes 115   Results of all full-scale crash tests and simulations were compared by plotting the barrier-top height against the maximum lateral extension of the vehicle for both the cab and trailer zones. Results of the cab overplot are shown in Figure 117, and results of the trailer overplot are shown in Figure 118. Lateral extensions of the cab decreased as barrier heights increased, and all test and simulation data were bounded by the proposed trend line except for historical data used for the RDG (AASHTO 2011). It is unclear if differences in RDG data were the result of changes in the tractor geometry, style, construction, suspensions, tires, or different interactions with the barrier, but no modern vehicles exhibited similar large cab extensions past the barrier face for barriers with heights of 42 in. or higher. It was noted that a distinctive reduction in lateral intrusion past the barrier face occurred for simulations of F-shape and vertical barrier geometries with a barrier-top height of 48 in. The 48-in.-tall barrier simulations resulted in lateral extensions less than those predicted for similar barrier geometries and barrier-top heights of 90 in. Many difficulties were encountered during simulation of the tractor-trailer impacts, and simulation results may underrepresent the extents observed in full-scale crash testing. However, full-scale crash testing is also highly variable, and results varied with similar system geometries and test vehicles. Because the single-slope barrier simulations were (1) associated with the largest lateral extents and (2) results of the single-slope simulations compared the best with the largest lateral offsets observed in full-scale crash testing, the recommended trailer zone ZOI envelopes for all barrier shapes were based on full-scale crash test and single-slope barrier simulations. No simulations or full-scale crash test data were available at the time of publication for bar- rier heights between 54 in. and 90 in. Researchers, therefore, extrapolated the trend lines for lower and higher points to estimate the maximum lateral protrusion of the cab and trailer zones Figure 117. Comparison of cab ZOI intrusion results for MASH TL-5 impact conditions: full-scale crash test data and computer simulations. 42 44 46 48 50 52 54 56 58 60 62 0 5 10 15 20 25 30 35 40 45 50 Ba rr ie r h ei gh t ( in .) Maximum extent (in.) MASH TL-5 Cab ZOI Intrusion Comparison (F-shape) Simulation (F-shape) 478130-1 (F-shape) 510605-RYU-1 (Single-slope) Simulation (Single-slope) 469489-1-3 (Single-slope) TL5CMB-2 (Single-slope) MAN-1 (Vertical) Simulation (Vertical) 405511-2 (Vertical) 469468-2-1 (Vertical) 490025-2-1 RDG - CS5 RDG - CV5 Lateral Extent Trend Line

116 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments 40 45 50 55 60 65 70 75 80 85 90 0 10 20 30 40 50 60 70 80 90 Ba rr ie r h ei gh t ( in .) Maximum extent (in.) MASH TL-5 Trailer ZOI Intrusion Comparison (F-shape) Simulation (F-shape) 478130-1 (F-shape) 510605-RYU-1 (Single-slope) Simulation (Single-slope) 469489-1-3 (Single-slope) TL5CMB-2 (Single-slope) MAN-1 (Vertical) Simulation (Vertical) 405511-2 (Vertical) 469468-2-1 (Vertical) 490025-2-1 RDG - CS5 RDG - CV5 Lateral Extent Trend Line Figure 118. Comparison of trailer ZOI intrusion results for MASH TL-5 impact conditions: full-scale crash test data and computer simulations. between 54- and 90-in.-barrier-top heights. Depending on the geometry of tall barriers, a por- tion of the cab may protrude past the front face of the barrier for heights up to 90 in., but these protrusions are believed to be limited and dependent on the cab shape. Because a full review and analysis of the cab geometries for different makes and models of trucks was beyond the scope of this study, researchers recommend that agencies consider a 2-in.-minimum lateral extension for the cab zone regardless of barrier height. The conservative extrapolations from the trend line are shown in Figures 119 and 120, and recommended ZOI envelopes for TL-5 shapes are summarized in Chapter 6.

Simulated ZOI Envelopes 117   Figure 119. Proposed cab zone lateral extents of ZOI envelopes for MASH TL-5 impact conditions. 42 44 46 48 50 52 54 56 58 60 62 0 5 10 15 20 25 30 35 40 45 50 Ba rr ie rh ei gh t ( in .) Maximum extent (in.) Proposed MASH TL-5 Cab ZOI Envelope Ranges (F-shape) Simulation (F-shape) 478130-1 (F-shape) 510605-RYU-1 (Single-slope) Simulation (Single-slope) 469489-1-3 (Single-slope) TL5CMB-2 (Single-slope) MAN-1 (Vertical) Simulation (Vertical) 405511-2 (Vertical) 469468-2-1 (Vertical) 490025-2-1 RDG - CS5 RDG - CV5 Lateral Extent Trend Line Recommended Lateral ZOI Limits 40 45 50 55 60 65 70 75 80 85 90 0 10 20 30 40 50 60 70 80 90 Ba rr ie rh ei gh t ( in .) Maximum extent (in.) Proposed MASH TL-5 Trailer ZOI Envelope Ranges (F-shape) Simulation (F-shape) 478130-1 (F-shape) 510605-RYU-1 (Single-slope) Simulation (Single-slope) 469489-1-3 (Single-slope) TL5CMB-2 (Single-slope) MAN-1 (Vertical) Simulation (Vertical) 405511-2 (Vertical) 469468-2-1 (Vertical) 490025-2-1 RDG - CS5 RDG - CV5 Lateral Extent Trend Line Recommended Lateral ZOI Limits Figure 120. Proposed lateral trailer zone extents of ZOI envelopes for MASH TL-5 impact conditions.