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

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9   Literature Review and Survey Background information on rigid barriers was collected from state DOT standard plans and specifications and MASH full-scale crash testing of Jersey, F-shape, single-slope, vertical, and low- profile barriers and steel bridge rails (AASHTO 2016). Information was not collected on W-beam guardrails, cable barriers, or other deformable, semi-rigid barrier systems. To supplement the literature review data, an agency survey was conducted to gather further information on minimum and maximum rigid barrier heights and concrete barrier shapes used at each MASH test level. Background information describing the development of the ZOI concept is shown below. A summary of the crash test database collected during the literature review, which supported the determination of minimum barrier heights, is shown in Appendix A. 2.1 ZOI Background and Development In 2010, MwRSF investigated the simulated ZOI of a 40-in.-tall, F-shape parapet under NCHRP Report 350 TL-2 and TL-3 criteria (Ross et al. 1993) as shown in Figure 5 (Hallquist 2007; Reid and Sicking 2010). Parameters believed to influence ZOI included tire-barrier friction, tire defla- tion, and suspension joint failure. Since these vary among crash tests, parametric studies were performed by varying each to bracket a conservative ZOI envelope. Investigated parameters included (1) no tire/suspension failure, (2) tire deflation permitted but not suspension dis- engagement, and (3) tire and suspension damage and disengagement permitted. Results of these parametric studies showed that these had little influence on ZOI. Overall kinematic behavior of the vehicle was affected, but the differences were observed primarily after maximum vehicle protrusion over the barrier occurred. The projected ZOI for a 40-in. F-shape concrete barrier impacted by a 4,410-lb pickup truck was between 1.8 in. and 2.5 in. for a 45-mph and 25-degree angle impact (TL-2) and 5 in. for a 62-mph and 25-degree angle impact (TL-3). In 2014, MwRSF analyzed the effect of barrier height on ZOI for 9.1-degree single-slope barriers for the Wisconsin Department of Transportation (WisDOT). Working widths were recorded during MASH test designation no. 3-11 simulations with heights of 36 in., 42 in., and 56 in. (Stolle, Reid, and Faller 2014). Note that working widths may be used as a surrogate for ZOI measure- ments. A Silverado truck model was used to compare simulated impact behavior to full-scale crash test results, as shown in Figure 6. Contact definitions, barrier material models, barrier mesh density, and time steps were optimized to improve the baseline simulation’s accuracy for the ZOI study. Critical ZOIs and working widths were evaluated, and each barrier was evaluated under multiple suspension failure conditions. Full-scale crash tests are the ideal tool to investigate impact scenarios and determine the ZOI for various rigid barriers. In 2008, MwRSF conducted an NCHRP Report 350 TL-3 pickup truck test on a concrete bridge pier protection system (Ross et al. 1993). The barrier consisted of C H A P T E R 2

10 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments ZOI Hood Barrier Figure 5. Forty-in.-tall F-shape barrier ZOI under NCHRP Report 350 criteria (Reid and Sicking 2010). Barrier Height (in.) Fender ZOI (in.) Hood ZOI (in.) Working Width (in.) 36 12.2 9.4 24.0 42 6.4 6.5 24.0 56 0 0 24.0 Figure 6. ZOI and working width for WisDOT 9.1-degree single-slope barrier simulation (Stolle, Reid, and Faller 2014). a 32-in.-tall vertical barrier with a bridge pier 16¾ in. behind the barrier’s front face (Rosenbaugh et al. 2008). e vehicle hood protruded 19.8 in. beyond the barrier’s front face and struck the bridge pier. e interaction between the hood and bridge pier did not negatively aect the crash test results. Although some vehicle hood deformation was observed, the vehicle redirected safely downstream, and thus occupant safety was not compromised during the test. Results of this full-scale crash test conrmed that vehicle extension into the ZOI may result in sti vehicle component contact with shielded features, but that the indication of contact did not necessarily contribute to unacceptable test outcome or excessive occupant risk. In 2008, MwRSF published a follow-up study to the barrier attachments research with a con- centrated eort on luminaires mounted within the ZOI (Wiebelhaus et al. 2008). ree NCHRP Report 350 (Ross et al. 1993) full-scale tests were conducted on a 32-in.-tall, 10.8-degree, single- slope barrier. A luminaire was mounted on top of the barrier, inside the ZOI envelope for a 32-in.-tall barrier. In the rst test, a 17,605-lb SUT impacted the barrier 55  upstream from the centerline of the luminaire. e vehicle struck the pole, which disengaged from the post base. e test was deemed successful as the luminaire impact did not cause signicant occupant risk. In the second test, a 4,430-lb pickup truck impacted the system 11  upstream from the center- line of the luminaire. e corner of the vehicle hood briey contacted the pole, and the vehicle redirected away from the system. e test was deemed successful. For the third test, a 17,637-lb SUT impacted the barrier 54  6 in. upstream from the centerline of the luminaire. e vehicle struck the pole, but the force was insucient to fracture and disengage the pole base, and the vehicle was safely redirected with acceptable occupant compartment deformation. In these tests, no deformations of or intrusion into the occupant compartment that could have caused serious injury occurred. e maximum ZOI of each test is shown in Figure 7. is testing conrmed that the previously developed ZOI envelopes were conservative.

Literature Review and Survey 11   In 2013, the Texas A&M Transportation Institute (TTI) evaluated signs placed on top of a Jersey barrier with MASH criteria (Abu-Odeh et al. 2013). A survey of the current state of the practice of mounting hardware on barriers was performed (Figure 8). Analysis, simulation, and crash testing were conducted to evaluate crashworthy hardware and develop placement guidelines. Four sign support congurations mounted to barriers were crash tested, and none interfered with the ability of the barrier to contain and redirect pickup trucks within MASH limits (AASHTO 2016). In 2019, TTI evaluated a 43--tall luminaire mounted on a 42-in.-tall, single-slope median barrier under MASH test designation no. 4-12, as shown in Figure 9 (Bligh et al. 2019). e barrier was anchored in a 1-in.-thick asphalt overlay for a total barrier height of 41 in. above the asphalt surface. During the impact event, the right-front corner of the cab began to wrap around the luminaire. e right-front corner of the cargo box contacted the luminaire, and the box roof and right sidewall disengaged from the vehicle. e test met all evaluation criteria for MASH test designation no. 4-12 (AASHTO 2016), although signicant damage occurred to the cargo box. Passenger vehicle tests were not conducted. Figure 7. NCHRP Report 350 (Ross et al. 1993) testing of luminaire on 10.8-degree single-slope barrier (Wiebelhaus et al. 2008). Figure 8. Sign mounted on concrete barrier (Abu-Odeh et al. 2013).

12 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments 2.2 Rigid Barrier Types Barriers are generally considered rigid if they do not deect when impacted. However, nearly all barriers examined had some dynamic deection occur during impact, and therefore a more specic denition was needed. For this study, a rigid barrier was dened as a barrier that would deect 10 in. or less during a MASH impact event. Rigid barriers were classied by shape and type, as shown in Figures 10 through 14. Low- prole barriers tested to NCHRP Report 230 (Michie 1981) or NCHRP Report 350 standards Figure 9. MASH testing of luminaire on 10.8-degree, single-slope barrier (Bligh et al. 2019). Figure 10. F-shape barrier (Bligh, Menges, and Kuhn 2018).

Literature Review and Survey 13   Figure 11. New Jersey shape barriers (Abu-Odeh et al. 2013; Polivka et al. 2006a; Buth and Menges 2012; Bhakta et al. 2018).

14 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 12. Single-slope barriers (Bligh, Menges, and Kuhn 2018; Rosenbaugh et al. 2021; Rosenbaugh et al. 2007; Sheikh, Bligh, and Menges 2011). Figure 13. Vertical barriers (Bligh, Menges, and Kuhn 2018; Williams, Bligh, et al. 2018).

Literature Review and Survey 15   (Ross et al. 1993) were also included; these barriers typically had a vertical face, were 18 to 20 in. tall, and met NCHRP Report 350 TL-1 or TL-2 criteria (Ross et al. 1993). e only MASH-tested barriers categorized as low-prole were at TL-1, which was not included in this study. Road- side and median congurations, temporary anchored barriers, and bridge rails were included in the review. Other systems, such as transitions and other uncategorized barrier shapes, were included if they deected less than 10 in. 2.3 Minimum Barrier Height Chapter 13 of the AASHTO LRFD [Load and Resistance Factor Design] Bridge Design Speci- cations (BDS) provided design forces and minimum rail heights for each test level (AASHTO 2017). Minimum rail heights for TL-2, TL-3, TL-4, and TL-5 were 27 in., 27 in., 32 in., and 42 in., respectively. However, these values had not been updated in many years and did not include MASH crash test results; recent research studies proposed new minimum barrier heights from those in the BDS (Shiekh, Bligh, and Menges 2011). Additionally, the BDS required a 54-in.-tall shielding barrier if a bridge pier were located within 10  of the barrier and a 42-in.-tall shielding barrier if a pier were more than 10  from the barrier due to concern for large trucks contacting and damaging piers. Full-scale crash test summaries performed according to MASH impact Figure 14. Steel and combination barriers (Williams and Bligh 2011; Williams, Bligh, and Menges 2012; Pena et al. 2020; Williams, Menges, and Kuhn 2015).

16 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments conditions (AASHTO 2016) were reviewed, as summarized below, and used to determine the minimum barrier heights shown in Section 2.7. 2.3.1 MASH TL-2 MwRSF conducted test no. IBBR-1 (Bielenberg et al. 2020) on a combination bridge rail to MASH test designation no. 2-11. e bridge rail was 48-in.-tall with a 24-in.-tall rail mounted on a 24-in.-tall concrete parapet, as shown in Figure 15. e 2270P pickup truck minimally contacted the upper rail, and the concrete parapet was believed to be the primary contributor to the containment and redirection of the vehicle. e maximum lateral ZOI measurement in test no. IBBR-1 occurred as the impact-side fender impacted a vertical post, buckled, and extended laterally behind the post. us, the lateral ZOI was believed to be higher during test no. IBBR-1 than would occur without the addition of the upper bicycle railing. 2.3.2 MASH TL-3 TTI conducted full-scale crash testing as part of NCHRP Project 20-07(Task 395) to com- pare pickup truck stability under NCHRP and MASH criteria (Silvestri Dobrovony et al. 2017). Results were inconclusive, and thus simulations were conducted with 27-, 28-, and 29-in.-tall vertical rigid barriers to establish a minimum barrier height for MASH TL-3. e 27-in. barrier simulation resulted in vehicle rollover. e 28-in. barrier simulation did not result in a rollover, Figure 15. MASH TL-2 combination bridge rail (Bielenberg et al. 2020). Numbers in brackets are mm equivalents.

Literature Review and Survey 17   but the vehicle was on the edge of instability. e 29-in. barrier simulation resulted in some roll motion, but the vehicle was fairly stable. erefore, the recommended minimum rail height for MASH TL-3 was 29-in. (Silvestri Dobrovony et al. 2017). No full-scale crash test was conducted to conrm this height. TTI conducted successful crash testing under MASH test designation no. 3-11 on the 26-in.- tall portable concrete barrier shown in Figure 16 (Silvestri Dobrovony et al. 2018). e barrier displaced up to 25-in. and thus was not included in this study. MwRSF conducted two successful full-scale crash tests under MASH test designation no. 3-11 on a timber noise wall with a rubrail with a top mounting height of 30 in., as shown in Figure 17 (Schmidt et al. 2019). e timber rubrail had a vertical face and was considered to behave similarly to a vertical, open concrete rail. e system deected up to 4.5 in. and was therefore considered rigid. In both crash tests, the pickup truck minimally interacted with the upper noise wall and was predominately redirected by the rubrail. Both tests displayed minimal vehicle roll. 2.3.3 MASH TL-4 Multiple 32-in.-tall concrete barriers were capable of redirecting SUTs under NCHRP Report 350 TL-4 criteria (Ross et al. 1993). However, an SUT rolled over 32-in.-tall Jersey bridge rails when tested to MASH TL-4 criteria (Polivka et al. 2006b; Bullard et al. 2010). us, the minimum barrier height for MASH TL-4 barriers was likely greater than 32 in. MwRSF conducted simulations to determine the barrier height necessary to prevent SUT rollover under MASH TL-4 criteria (Rosenbaugh et al. 2012). Simulations were conducted with and without suspension failure as it was unknown how suspension would perform in full-scale crash testing. A vertical-faced barrier with a 34½-in. height was adequate for redirecting an SUT and preventing rollover. No full-scale crash testing was conducted to conrm this behavior. In 2011, TTI conducted a simulation study and full-scale crash test according to MASH test designation no. 4-12 on a 36-in.-tall, single-slope concrete barrier with an 11-degree slope on the trac-side face, as shown in Figure 18 (Sheikh, Bligh, and Menges 2011). e test was successful, and 36 in. was considered the minimum MASH TL-4 height for all barrier proles. Figure 16. MASH TL-3 low-prole portable barrier (Silvestri Dobrovony et al. 2018).

18 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 17. MASH TL-3 timber noise wall and rubrail system (Schmidt et al. 2019). Figure 18. MASH TL-4 single-slope barrier (Sheikh, Bligh, and Menges 2011).

Literature Review and Survey 19   Additional successful crash tests have been conducted on 36-in.-tall MASH TL-4 barriers. In 2018, MwRSF tested a 36-in.-tall, 3.2-degree single-slope barrier under MASH test designa- tion no. 4-12, as shown in Figure 19 (Rosenbaugh et al. 2021). In 2018, TTI tested a 36-in.-tall, vertical concrete barrier under MASH test designation no. 4-12, as shown in Figure 20 (Bligh, Menges, and Kuhn 2018). In 2019, MwRSF tested a 36-in.-tall steel tube bridge rail under MASH test designation nos. 4-10, 4-11, and 4-12, as shown in Figure 21 (Pena et al. 2020). Each of these tests was deemed successful, and thus, several 36-in.-tall barriers were considered Figure 19. MASH TL-4 single-slope barrier (Rosenbaugh et al. 2021). Numbers in parentheses are mm equivalents. Figure 20. MASH TL-4 vertical bridge rail (Bligh, Menges, and Kuhn 2018).

20 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments crashworthy under MASH TL-4 criteria. Additionally, during a study conducted by TTI for NCHRP Project 22-07(Task 395), a minimum barrier height of 36 in. was used for MASH TL-4 (Silvestri Dobrovony et al. 2018). 2.3.4 MASH TL-5 The TL-5 minimum barrier height as established in the BDS is 42 in. (AASHTO 2017), based on successful full-scale crash testing. MASH TL-5 criteria had only minor revisions from NCHRP Report 350 TL-5 (Ross et al. 1993), and therefore it was believed 42 in. was also the minimum barrier height necessary for MASH TL-5. During NCHRP Project 22-07(Task 395), TTI researchers also used a minimum barrier height of 42 in. for MASH TL-4 (Silvestri Dobrovony et al. 2018). Additional full-scale MASH crash tests were conducted on 41.3- and 42-in.-tall concrete barriers, as shown in Figures 22 through 24. Though one crash test was successful at a height below 42 in., it was the only successful test at this height, and it was uncertain if results were applicable to other barrier profiles besides the tested profile. Additionally, the top height was not significantly different from the recommended 42-in. minimum height. Figure 21. MASH TL-4 steel tube bridge rail (Pena et al. 2020). (Numbers in parentheses are millimeter equivalents.)

Literature Review and Survey 21   Figure 22. MASH TL-5 Jersey barrier (Buth and Menges 2011). (Dimensions are presented in mm.) 2.4 Existing Rigid Barrier Simulations Finite element analysis (FEA) is a valuable tool for estimating interactions between vehicles and barriers or other features at a lower expense than constructing barrier systems and conduct- ing full-scale crash tests. Simulation parameter studies vary widely and may not be consistent between agencies, barriers, or test articles. Researchers use full-scale crash test data to validate the combination of barrier, vehicle, friction, damage, and material parameters, replicating test results as near as possible. These validated parameters were used to develop new barriers, inves- tigate end effects, or estimate vehicle interaction with features in the ZOI. MwRSF researchers reviewed 25 simulation studies involving vehicle-barrier impacts from technical reports, journal papers, and public presentations, as summarized in Tables 4 and 5. Parameters investigated included wheel and suspension failure, vehicle-barrier and vehicle- ground friction coefficients, and barrier shapes. While the focus was primarily on rigid barriers, a few simulation studies from non-rigid barriers were collected as some vehicle-barrier impact parameters (e.g., friction) may be similar. The vehicles typically used included modified versions of full vehicle models produced by the National Crash Analysis Center or the Center for Crash Safety and Analysis, which are publicly available through the National Highway Traffic Safety Administration (NHTSA n.d.). Older vehicle models included a Geo Metro, a ¾-ton Chevrolet C2500, and a box truck consistent with NCHRP Report 350 820C, 2000P, and 8000S test vehicles,

22 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments Figure 23. MASH TL-5 Jersey barrier (Buth and Menges 2012). (Dimensions are presented in mm. 12M and 15M = the size of rebar; C/C = center to center.) Figure 24. MASH TL-5 open concrete bridge rail (Williams, Sheikh, et al. 2018).

Literature Review and Survey 23   Simulation Ref. No. Authors Title Report No. / Paper No. Publishing Agency Publishing Location Publishing Year 1 Bligh, R.P., Abu-Odeh, A.Y., Hamilton, M.E., and Seckinger, N.R. Evaluation of Roadside Safety Devices Using Finite Element Analysis FHWA/TX-04/0- 1816-1 TTI College Station, Texas 2004 2 Bligh, R.P., Sheikh, N.M., Menges, W.L., and Haug, R.R. Development of Low- Deflection Precast Concrete Barrier FHWA/TX-05/0- 4162-3 TTI College Station, Texas 2005 3 Beason, W.L., Sheikh, N.M., Bligh, R.P., and Menges, W.L. Development of a Low-Profile to F-Shape Transition Barrier Segment Report 0-5527-1 TTI College Station, Texas 2007 4 Sheikh, N.M., Bligh, R.P., and Menges, W.L. Analysis, Design, and Dynamic Evaluation of a TL-2 Rough Stone Masonry Guardwall 405160-3-1&2a TTI College Station, Texas 2008 5 Sheikh, N.M., Bligh, R.P., and Menges, W.L. Zone of Intrusion Study Report 405160-13-1 TTI College Station, Texas 2009 6 Johnson, E.A., Faller, R.K., Reid, J.D., Sicking, D.L., Bielenberg, R.W., Lechtenberg, K.A., and Rosenbaugh, S.K. Determination of Minimum Height and Lateral Design Load for MASH Test Level 4 Bridge Rails TRP-03-217-09 MwRSF Lincoln, Nebraska 2009 7 Reid, J.D., and Sicking, D.L. Design Guidelines for Test Level 3 (TL-3) Through Test Level 5 (TL-5) Roadside Barrier Systems Placed on Mechanically Stabilized Earth (MSE) Retaining Wall TRP-03-242-10 MwRSF Lincoln, Nebraska 2010 8 Sheik, N.M., Bligh, R.P., and Menges, W.L. Phase I Development of an Aesthetic, Precast Concrete Bridge Rail Test Report 9- 1002-5 TTI College Station, Texas 2011 9 Barrios, D.O.S. Signs on Concrete Median Barriers TAMU College Station, Texas 2012 10 Rosenbaugh, S.K., Faller, R.K., Bielenberg, R.W., Sicking, D.L., and Reid, J.D. Modified NETC 4-Bar Bridge Rail for Steel Through-Truss Bridges TRP-03-239-12 MwRSF Lincoln, Nebraska 2012 11 Abu-Odeh, A., Williams, W., Ferdous, R., Spencer, M., Bligh, R., and Menges, W. Crash Test & Simulation Comparisons of a Pickup Truck & a Small Car Oblique Impacts Into a Concrete Barrier Report 0-6646-1 TTI College Station, Texas 2013 12 Plaxico, C.A., and Ray, M.H. Zone of Intrusion for Permanent 9.1-Degree Single- Slope Concrete Barriers Unk Roadsafe LLC Canton, Maine 2013 13 Marzougui, D., Kan, C.D., and Opiela, K.S. Impact performance evaluation of MASH TL4 bridge Barrier N/A TTI College Station, Texas 2014 14 Stolle, C.J., Reid, J.D., and Faller, R.K. Development of a Retrofit, Low-Deflection, Temporary Concrete Barrier System TRP-03-292-13 MwRSF Lincoln, Nebraska 2014 15 Parka, K.-S., Noha,M.-H., and Leeb, J. Design and Evaluation of an Energy-Absorbing, Reusable Roadside/Median Barrier International Journal of Crashworthiness TTI College Station, Texas 2014 16 Bielenberg, R.W., Quinn, T.E., Faller, R.K., Sicking, D.L., and Reid, J.D. MASH TL5 Evaluation of the Proposed Three-Rail Barrier TRP-03-295-14 MwRSF Lincoln, Nebraska 2014 17 Schmidt, J.D., Rosenbaugh, S.K., Faller, R.K., Bielenberg, R.W., Reid, J.D., Lechtenberg, K.A., Report 350 TL4 Evaluation of the Proposed Three-Rail Barrier TRP-03-317-15 MwRSF Lincoln, Nebraska 2015 Holloway, J.C., and Kohtz, J. E. Table 4. Rigid barrier impact simulations studies. (continued on next page)

24 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments 18 Plaxico, C.A., and Ray, M.H. MASH TL5 Evaluation of the Proposed Three-Rail Barrier Unknown Roadsafe LLC Canton, Maine 2016 19 Plaxico, C.A., and Johnson, T.O. Report 350 TL4 Evaluation of the Proposed Three-Rail Barrier Unknown Roadsafe LLC Canton, Maine 2016 20 Schmidt, T.L., Faller, R.K., Schmidt, J.D., Reid, J.D., Bielenberg, R.W., and Rosenbaugh, S.K. Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Buttress TRP-03-336-16 MwRSF Lincoln, Nebraska 2016 21 Pajouh, M.A., Schmidt, J.D., Bielenberg, R.W., and Faller, R.K. Development of a Transition Between Free-Standing and Reduced-Deflection Portable Concrete Barriers – Phase I TRP-03-366-17 MwRSF Lincoln, Nebraska 2017 22 Plaxico, C.A., and Johnson, T.O. Evaluation and Design of a TL3 Bridge Guardrail System Mounted to Steel Fascia Beams Unknown Roadsafe LLC Canton, Maine 2017 23 Bhakta, S.K., Lechtenberg, K.A., Fang, C., Faller, R.K., Reid, J.D., Bielenberg, R.W., and Urbank, E.L. Performance Evaluation of New Jersey’s Portable Concrete Barrier with a Box-Beam Stiffened Configuration and Grouted Toes – Test No. NJPCB-5 TRP-03-372-18 MwRSF Lincoln, Nebraska 2018 24 Marzougui, D., Kan, C.D., Mahadevaiah, U., Tahan, F., Story, C., Dolci, S., Moreno, A., Opiela, K.S., and Powers, R. Evaluating the Performance of Longitudinal Barriers on Curved, Superelevated Roadway Sections NCHRP Research Report 894 Center for Collision Safety and Analysis (CCSA) Washington, DC 2018 25 Williams, W.F., Sheikh, N.M., Menges, W.L., Khun, D.L., and Bligh, R.P. Crash Test and Evaluation of Restrained Safety-Shape Concrete Barriers on Concrete Bridge Deck Report 9-1002-15-3 TTI College Station, Texas 2018 Authors Title Report No. /Paper No. Publishing Agency Publishing Location Publishing Year Simulation Ref. No. Table 4. (Continued). Table 5. Rigid barrier impact simulations. Test No. VehicleModel Barrier Barrier Height (in.) Impact Conditions Friction ValuesSpeed (mph) Angle (deg.) 1 Unknown C2500 T6 bridge rail 31 62 25 Unknown C2500 Grid-slot portable concrete 32 62 25 2 441623-1 C2500 TxDOT type 2 PCTB(1)-90 with joint type A 32 62 25 3 455276-1-2 Silverado Low-profile to F-shape transition 20 to 32 43 20 Barrier-ground: 0.4 455276-1-3 Metro Low-profile to F-shape transition 21 to 32 43 20 Barrier-ground: 1.4 4 405160-3-1, 405160-3-2a C2500 WisDOT pinned 32 62.2 25 5 405160-13-1 Modified C2500 Single slope 32 62 25 6a RSMG-1 C2500 Stone guardwall 22 43.5 20 Tire-barrier: 0.4; vehicle-barrier: 0.05 RSMG-2 C2500 Stone guardwall 20 43.5 25 Tire-barrier: 0.4; vehicle-barrier: 0.05 7a 2000P F-shape 40 45, 62 25 Tire-barrier: 0.05 - 0.6 8 10000S SUT TL-4 bridge rail 36 to 39, 42 56 15 Simula- tion Ref. No.

Literature Review and Survey 25   Table 5. (Continued). Test No. VehicleModel Barrier Barrier Height (in.) Impact Conditions Friction ValuesSpeed (mph) Angle (deg.) 9 10000S SUT Jersey 36, 39, 56 15 10000S SUT Tall vertical wall Unknown 56 15 Tractor- trailer Jersey 42, 48, 54 50 15 Tractor- trailer Tall vertical wall 42 50 15 10 10000S SUT Precast concrete bridge rail 34.5, 36.5 50 15 11 476460-1-4 Silverado Jersey safety shape 32 62.6 25.2 Silverado Jersey safety shape with sign support on top 32 62.2 25 12 4600LP NETC 4-bar bridge rail 42 50 15 13 Silverado Jersey 32 62.6 25 Yaris Jersey 32 62.6 25 14 420020-3 Silverado TxDOT 10.8-degree single slope 62 25 Tire-barrier: 0.15 - 0.45; vehicle-barrier: 0.05 - 0.4 Silverado 9.1-degree single slope 36, 42, 56 62 25 15 Unknown Kia Rio MASH TL-4 bridge rail 53 62 25 Unknown RAM MASH TL-4 bridge rail 53 62 25 Unknown International 4700 MASH TL-4 bridge rail 53 53 15 16 TB-2 Silverado F-shape temporary 32 62 25 17 MAN-1 Tractor-trailer Single slope 42 51.7 15.2 Tractor- trailer Modified bridge rail 45 51.7 15 18 404201-7 Metro Oregon three-tube bridge rail 62.6 19.7 404201-8 C2500 Oregon BR208 bridge rail 62.6 25.4 404201-9 8000S Oregon three-tube bridge rail Unknown Unknown Unknown Unknown 50.45 15 19 SFH-1 Silverado RESTORE 38.6 63.4 25 Tire-barrier: 0.1; vehicle-barrier: 0.1 SFH-3 F800 RESTORE 38.6 56.5 15 Tire-barrier: 0.1; vehicle-barrier: 0.1 SFH-2 Yaris RESTORE 38.6 64.3 25 Vehicle-barrier: 0.1 SFH-2 Neon RESTORE 38.6 64.3 25 Tire-barrier: 0.3; vehicle-barrier: 0.1 Neon RESTORE 32 62 25 Tire-barrier: 0.1 - 0.3; vehicle-barrier: 0.1 Silverado RESTORE 32 62 25 Tire-barrier: 0.1 - 0.3; vehicle-barrier: 0.1 10000S SUT RESTORE 32 57.2 15 Tire-barrier: 0.1 - 0.3; vehicle-barrier: 0.1 20 TCBT-1 Silverado F-shape portable 42 63.6 24.9 Vehicle-barrier: 0.4 TCBT-2 Silverado F-shape portable 42 64.8 25.4 Vehicle-barrier: 0.24 21 7069-35 Yaris Modified Illinois bridge rail 32 62 25 7069-36 Silverado Modified Illinois bridge rail 32 62 25 7060-37 F800 Modified Illinois bridge rail 32 51.4 15 22 NJPCB-3 Silverado Jersey PCB 32 62.1 25 Vehicle-barrier: 0.1; barrier-ground: 0.2 NJPCB-5 Silverado Jersey PCB 32 62.1 25 Vehicle-barrier: 0.1; barrier-ground: 0.2 23 2214NJ-1, 476460-1-4 Silverado Jersey 32 62.6 25 Tire-ground: 0.9 2214NJ-1, 476460-1-5 Yaris Jersey 34 62.6 25 Tire-ground: 0.9 24 490027-2-1 10000S SUT PCB 42 56 15 a Simulation included joint suspension failure. NOTE: Shading was used to indicate that model calibration with full-scale testing was not discussed. Simula- tion Ref. No. 42

26 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments respectively (Ross et al. 1993). Newer vehicle models included a Toyota Yaris, a ½-ton Chevrolet Silverado quad cab, a modified box truck consistent with MASH 1100C, 2270P, and 10000S test vehicles, respectively (AASHTO 2016); the Silverado was most commonly used. Note that rows shaded in Table 5 indicated that it was not reported that the simulations utilized test data to calibrate impact models. Most simulations were consistent with MASH TL-3 impact conditions (AASHTO 2016). Rigid barrier shapes used for comparison included vertical RESTORE barriers, Jersey and F-shape temporary and permanent barriers, single-slope barriers, and vertical steel bridge rail systems. Most systems used for model validation ranged between 32 and 42 in. tall. Little information was available regarding values used or recommended for vehicle- or tire-barrier friction values. Friction values obtained from simulation reports ranged from 0.05 to 0.4 for vehicle-barrier, 0.1 to 0.45 for tire-barrier, 0.2 to 1.4 for barrier-ground, and 0.9 for tire-ground. Few reports compared ZOI results between simulation and full-scale testing as part of model validation or recorded ZOI protrusion of any stiff element components. Previously, MwRSF used simulations to investigate the ZOI of F-shape and single-slope parapets according to MASH TL-3 impact conditions (Reid and Sicking 2010; Stolle, Reid, and Faller 2014) and found tire friction, tire deflation, suspension component failure, and combinations thereof typically occurred early in the event and had little influence on ZOI. The ZOI for a 40-in. F-shape concrete barrier impacted by a 4,410-lb pickup truck at 45 mph and a 25-degree angle (NCHRP Report 350 TL-2) was estimated to be between 1.8 in. and 2.5 in., and at 62 mph and a 25-degree angle (NCHRP Report 350 TL-3) was estimated to be 5 in. (Ross et al. 1993). The ZOI for a single-slope concrete barrier impacted by a 5,000-lb pickup truck at 62 mph and a 25-degree angle (MASH TL-3) was estimated to be 12.2 in., 6.5 in., and 0.0 in. for 36-, 42-, and 56-in.-tall barriers, respectively. In 2018, guidelines were developed for shielding bridge piers using crash test results supplemented with simulation data to estimate the maximum lateral vehicle extent behind the front barrier face for varying heights, as shown in Figure 25 (Ray, Carrigan, and Plaxico 2018). In tractor-trailer simulations, the vehicle-barrier, tire-barrier, and tire-ground friction coefficients were 0.2, 0.45, and 0.7, respectively. Researchers recommended at least 39 in. from the top traffic-side face of the 0 5 10 15 20 25 42 44 46 48 50 52 54 M ax . l at er al e xt en t o f c ar go b ox (i n. ) Barrier height (in.) Front of box Rear of box SUT 16317-40 Maximum cargo box lateral extent, MASH TL-4 and TL-5 Figure 25. NCHRP Research Report 892 (TL-4 and TL-5 simulation, maximum lateral vehicle extent behind barrier) (Ray, Carrigan, and Plaxico 2018).

Literature Review and Survey 27   shielding barrier to an adjacent bridge pier to prevent pier contact. Results indicated that the SUT cab was unlikely to extend over the top of barriers greater than or equal to 48 in. tall and that the rear of the box was typically the largest lateral extent recorded in a TL-4 test. Suspension failure was included to predict wheel damage and displacement, but only one study described the technique used for suspension failure modeling: a timed release of joint definitions of the impacting front wheel of a pickup truck. In general, suspension failure was not considered critical to simulated system performance. 2.5 In-Service Performance Data Crashes that engage features located within the ZOI of rigid barriers pose additional risk to occupants of impacting vehicles, but relatively little published information identified if these features caused severe or fatal injuries. Researchers conducted a limited in-service per- formance evaluation (ISPE) to identify fixed objects within the ZOI of rigid barriers struck by impacting vehicles and the associated adverse crash outcomes (fatality or serious injury, rollover, or vehicle vaulting or penetration). Information was collected from research reports, crash records, and anecdotal accounts. Due to time and funding constraints, this chapter represents an anecdotal perspective and should not be interpreted as a comprehensive ISPE. Note that a comprehensive ISPE may include the determination of exposure (i.e., how many objects are located within the ZOI and could be struck), frequency of impacts with objects located in the ZOI, identification of injury severities in those crashes, and analysis of critical outcomes and contributing factors observed during crashes in which vehicles engaged with objects located in the ZOI. 2.5.1 Research Reports Very few rigid barrier ISPEs focused on supplementary impacts or ZOI protrusion, instead primarily focusing on benefit-to-cost ratios for barrier types or shapes, construction optimiza- tion, crash modification factors, and overall risk of adverse crash outcomes. Due to low rel- evancy to this research effort, few of these studies were considered in detail. A 1990 review of Texas DOT crash data and simulated impacts with Jersey barriers analyzed impact angle and vehicle orientation at the impact point (Mak and Sicking 1990). Barrier “glare screens” were treated as extensions of the barrier, although the glare screens caused additional scrubbing and snagging during simulation. Due to simulation difficulties and the limited number of real-world crashes with glare screens on barriers, conclusions regarding glare screens or other fixed objects within the ZOI were limited. Albuquerque and Sicking described the propensity for concrete barrier shapes to produce rollovers using Iowa crash data (Albuquerque and Sicking 2013, Albuquerque and Sicking 2011). Safety-shape barriers were twice as likely as vertical rails to produce a rollover during crash events and were associated with more severe injuries, although injury correlation was not statistically significant. Fixed objects located within the ZOI may have an adverse effect on motorcyclists during impact. Berg described the risks of motorcyclists impacting various 800-mm-tall barrier types through full-scale crash testing with upright dummies impacting steel and concrete barriers at 60 km/h and a 12-degree angle, resulting in the dummy ejecting from the motorcycle and launching behind the barrier (Berg et al. 2005). Conversely, Daniello and Gabler (2011) found concrete barrier impacts were associated with reduced motorcyclist injury risk compared to post-and-beam systems and cable barriers, although findings were not statistically significant.

28 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments A 2012 review of large-truck impacts with roadside barriers noted a decreased propensity for barrier penetration, vaulting, and override as the rated barrier performance increased using NCHRP Report 350 testing and barrier height differentiators (Gabauer 2012). However, impacts with fixed objects or features within barrier ZOIs were not a focus of the research. The 2018 bridge pier guidelines study discussed in Section 2.4 found that the majority of impact force and subsequent damage when a pier was struck by a large truck came from the cab (Ray, Carrigan, and Plaxico 2018). The truck box contacting the pier was only a concern if the box was carrying a rigid load at a high speed. Twenty-four prior crash tests were identified, including 10 using 80,000-lb tractor-trailers, two using 50,000-lb tractor-trailers, and 12 using SUTs between 18,000 and 22,000 lb; most were performed using nominal 50-mph impact speeds and 15-degree impact angles. In some unsuccessful full-scale crash tests the tractor-trailer rolled over the top of the barrier, and the trailer extended up to 16 ft laterally. Much less lateral extension over the rail occurred in successful full-scale crash tests performed to MASH (AASHTO 2016) or NCHRP Report 350 criteria (Ross et al. 1993). A minimum of 39 in. was recommended from the top traffic-side face of the shielding barrier to an adjacent bridge pier to prevent pier contact. In 2016, Purdue University conducted an ISPE of concrete walls, W-beam guardrails, and high-tension cable barriers installed on divided roadways in Indiana (Zou and Tarko 2016). The main conclusions were that more crashes occurred with barriers present, and cable barriers performed better than concrete walls or W-beam guardrails. However, no specific data on crashes with fixed objects adjacent to concrete walls were presented. 2.5.2 Case Studies News reports, online videos, and narrow case studies involving impacts with a feature in the ZOI were considered relevant to this study to provide examples of potential real-world hazards. Because they were not collected algorithmically as part of a database and depended on search engine queries, crashes in this section were considered anecdotal, and there was no associated analysis to determine the frequency or likelihood of similar collisions. 2.5.2.1 Van Overrode Bridge Rail In Dania Beach, Florida, in October 2016, a van impacted a concrete barrier and came to rest partly extended over the top of the rail, as shown in Figure 26 (Stone 2016). Although no secondary impact occurred, there was clear evidence of protrusion and risk in the ZOI. Figure 26. Van overrode bridge rail (Stone 2016).

Literature Review and Survey 29   2.5.2.2 Pickup Truck Overrode Bridge Rail A pickup truck impacted a single-slope median barrier in Milwaukee in May 2018, partly vaulting and riding on top of the barrier and striking multiple luminaires, as shown in Figure 27 (Jones 2018). The luminaires broke away during impact and fell onto the travel lanes, resulting in lane closures, delays, and cleanup. No vehicles were struck by the falling luminaires. 2.5.2.3 Tank Trailer Impacted Bridge Pier On January 3, 2019, a large truck with a tank trailer collided with a roadside concrete barrier near Hagerstown, Maryland, resulting in a portion of the cab protruding over the top surface of the barrier into the ZOI and striking a bridge pier, as shown in Figure 28 (Dearth 2019). The crash ignited a vehicle fire and resulted in a driver fatality. The roadside barrier was not noted in news reports; visual inspection suggested it was a safety-shape barrier. 2.5.2.4 Pickup Truck Overrode F-Shape Barrier In June 2018 near Baton Rouge, Louisiana, a pickup truck overrode a concrete barrier following an impact with a tractor-trailer, as shown in Figure 29 (Segura 2018). The truck came to rest straddling the concrete rail and against the side of the truck trailer. No serious injuries were reported. 2.5.2.5 SUT Impacted Bridge Pier In Mansfield, Rhode Island, in November 2018, two serious injuries were reported after an SUT collided with an F-shape roadside barrier, causing the cab to extend over the top of the Figure 27. Pickup truck overrode single-slope median barrier (Jones 2018). Figure 28. Tank trailer impacted bridge pier (Dearth 2019).

30 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments barrier and collide with a bridge pier, as shown in Figure 30 (Linton 2018). The impact resulted in the SUT rolling onto its right side. The bridge pier experienced concrete cracking and spalling, resulting in exposed rebar. 2.5.2.6 Tank Truck Impacted Bridge Pier A large truck towing a gasoline tank trailer departed the roadway in Franklin, Tennessee, in August 2014, crashing into a roadside barrier and extending into the ZOI, as shown in Figure 31 (Tamburin 2014). The crash resulted in a driver fatality and a fire that required more than an hour to extinguish. The bridge piers were damaged during the crash and subsequent fire. The roadside barrier was not noted in news reports; visual inspection suggested it was a safety-shape barrier. Figure 29. Pickup truck overrode F-shape barrier (Segura 2018). Figure 30. SUT Impacted bridge pier (Linton 2018).

Literature Review and Survey 31   2.5.3 Summary Prior ISPEs and anecdotal crashes were reviewed to observe the severity and characteristics of crashes with fixed objects adjacent to barriers. A detailed ISPE using this process was impos- sible as it was difficult to determine (1) if a fixed object was adjacent to a barrier, (2) barrier height and shape, (3) where the fixed object was located laterally and longitudinally in relation to the barrier, (4) if the fixed object contributed to injuries, and (5) impact conditions including speed, impact angle, and vehicle orientation at the point of impact. Fatal or severe crashes are more likely to receive news coverage and therefore will be disproportionately represented in any study that relies on search engine queries. It was likely the frequency of crashes with fixed objects behind a barrier was relatively low, although no specific data confirmed this hypothesis. It was believed there may be fewer crashes and severe crashes with fixed objects adjacent to barriers as many transportation agencies follow ZOI guidance from the RDG (AASHTO 2011). 2.6 Review of State DOT Standard Plans State DOT standard plans, design details, and specifications for rigid barrier systems were col- lected from state websites. Additional installation guidelines and general information on the follow- ing barrier systems were collected: • Jersey barriers (32 to 54 in. tall). • F-shape concrete barriers (32 to 51 in. tall). • Single-slope barriers (32 to 112.5 in. tall). • Vertical barriers (32 to 54 in. tall). • Open concrete barriers (27 to 42 in. tall). • Steel barriers (30 to 50 in. tall). Note the 112.5-in.-tall single-slope barrier was used in only one state to separate roadways of varying grades. Several websites lacked barrier design and construction data, while others had addi- tional information such as usage and test barrier equivalency. However, few standard plans explicitly denoted whether equivalency applied for NCHRP Report 350 (Ross et al. 1993) or MASH criteria (AASHTO 2016), and thus it was difficult to make conclusions about rigid barrier usage specific to MASH criteria. State DOT plans were used to supplement survey responses on barrier usage. Figure 31. Tank truck impacted bridge pier (Tamburin 2014).

32 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments 2.7 Agency Survey 2.7.1 Overview An agency survey was conducted to obtain information on rigid barrier shapes and heights used by state DOTs at each test level, available in-service performance data related to rigid barriers and attachments near barriers, and any updates in rigid barrier standards and specifications from what is available online. The complete survey is provided in Appendix B. DOTs from AK, AL, AZ, CA, FL, GA, HI, IA, IL, IN, KS, LA, MD, MI, MN, MT, NC, NE, NJ, NM, NV, NY, OH, PA, SC, TN, TX, UT, VT, VA, WI, and WY responded; one reported very little rigid barrier usage and did not complete the survey, and thus 31 state DOTs completed the survey questions. 2.7.2 Discussion Some states reported they did not use a particular test level for minimum and maximum barrier heights, and some states did not respond. It may be inferred that states that did not respond either do not use rigid barriers at a particular test level or have no current plan in place. For the states that did not respond with a minimum or a maximum barrier height at a particular test level, it was assumed minimum and maximum heights were the same. Several states listed “MASH minimum” in response to one or more questions about their minimum height for certain test levels. In other research, minimum heights for MASH TL-3, TL-4, and TL-5 were established at 29 in., 36 in., and 42 in., respectively. For MASH TL-3, this was determined based on simulation and not full-scale crash testing. For MASH TL-2, a minimum height had not been determined. Based on prior testing described in the literature review, the preliminary minimum height for MASH TL-2 was thought to be 24 in. Thus, 24 in., 29 in., 36 in., and 42 in. were entered for “MASH minimum” survey responses at MASH TL-2, TL-3, TL-4, and TL-5, respectively, and applied to a vertical barrier and other barrier shapes at that height. The minimum may be higher for certain barrier shapes, such as those with sloped front faces. Preliminary minimum and maximum barrier height thresholds at each test level are discussed in Section 2.8. Many state DOTs used ZOI criteria if there was a need to place a fixed object adjacent to a barrier. State DOTs used various barrier shapes, but single-slope barriers were the most common across all test levels. State DOTs used different barrier heights at each test level, and many exceeded minimum height requirements. Thus, it was recommended to develop ZOI envelopes to accom- modate a wide range of barrier heights and shapes. Most state DOTs had not conducted ISPEs on attachments to rigid barriers or rigid barriers themselves. Conducting an ISPE using crash data was outside the scope of this project, and it would be difficult to isolate crashes involving a fixed object located adjacent to a rigid barrier or to determine whether the fixed object affected vehicle behavior. Some state DOTs noted that objects—such as luminaires, overhead sign structures, noise walls, and mechanically stabilized earth (MSE) walls mounted on top of or adjacent to barriers and likely within the ZOI of the barriers—have been contacted by vehicles. As discussed and shown in Figure B-13 in Appendix B, the severity of crashes involving overhead sign structures shielded by a rigid barrier ranged significantly. Sound barriers were often placed within the ZOI of rigid barriers in urban areas for residential noise mitigation. According to Chapter 15 of the BDS, sound barriers should be crash tested or use components designed with Extreme Event II forces (AASHTO 2017). During some sound barrier crash tests, contact marks and damage occurred, but the tests were successful (Schmidt et al. 2019; Bullard et al. 2001; Polivka et al. 2005). Thus, sound barriers successfully tested in

Literature Review and Survey 33   combination with a barrier can be used without consideration of ZOI envelopes. However, sound barriers that have not been crash tested may cause vehicle components to snag on barrier components if located within the ZOI, although the potential extent of snag for each system is unknown. Careful planning, review, and investigation of crashworthy options may be required for safe and effective sound wall installation. Many of the additional comments are addressed throughout this report. One comment sug- gested ZOI envelopes be reported for each crash test as conducted. Although ZOI documenta- tion is not currently required for test documentation, it is recommended that all full-scale testing report ZOI values using a similar method to those in Chapter 6. 2.8 Barrier Height Thresholds Preliminary MASH barrier height thresholds were determined based on the literature review and agency survey and are summarized in Table 6. The maximum barrier height at each test level often differed for steel and concrete barriers due to availability (e.g., there was no 90-in.-tall steel barrier) and differences in state DOT steel standards (e.g., different barriers or accounting for overlays). Barriers taller than the minimum were used to reduce the likelihood of vehicle extension beyond the front barrier face or as glare screens. Some of these barrier heights were not common but are reported here for completeness. 2.8.1 MASH TL-2 Few full-scale crash tests or simulations were conducted at MASH TL-2, and thus the mini- mum barrier height was unknown. MwRSF conducted a MASH TL-2 crash test on a 48-in.-tall combination bridge rail with a 24-in.-tall steel structure mounted on a 24-in.-tall concrete parapet (Bielenberg et al. 2020). Since the concrete parapet was the primary contributor to the containment and redirection of the pickup truck, a 24-in.-tall vertical concrete barrier was believed to be the minimum barrier height for MASH TL-2. It was unknown if the minimum barrier height would be different for other barrier shapes. The maximum MASH TL-2 barrier height used by state DOTs was 54 in. 2.8.2 MASH TL-3 During a simulation study conducted by TTI for NCHRP Project 22-07(Task 395), the rec- ommended minimum rail height for MASH TL-3 was 29 in. (Silvestri Dobrovony et al. 2017); however, no full-scale crash tests confirmed this. MwRSF conducted two full-scale crash tests to MASH test designation no. 3-11 criteria on a rigid timber noise wall with a rubrail with a top MASH TL Barrier Height (in.) Min.a Max. Concrete Max. Steel 2 24 54 54 3 29 57 56 4 36 90 56 5 42 90 54 a Some state agencies used lower heights than shown. Values are based on the literature review in Section 2.3, and lower barrier heights are not recommended without full-scale testing. Table 6. Range of typical barrier heights.

34 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments mounting height of 30 in., which had minimal roll and stable redirection (Schmidt et al. 2019). Based on these results, it was anticipated a shorter rail could also redirect a MASH TL-3 pickup truck. TTI conducted successful MASH TL-3 crash testing on a 26-in.-tall portable concrete barrier, which deflected significantly, but it was unknown if shorter MASH TL-3 rigid barriers would be successful (Silvestri Dobrovony et al. 2018). Based on these studies, it was assumed that 29 in. was the preliminary minimum barrier height for a MASH TL-3 vertical barrier. It was unknown if the minimum barrier height would be different for other barrier shapes. The maximum MASH TL-3 barrier height used by state DOTs was 57 in. 2.8.3 MASH TL-4 After unsuccessful crash tests with 32-in.-tall barriers (Polivka et al. 2006a; Bullard et al. 2010), several successful crash tests were conducted with 36-in. barrier heights (Sheikh, Bligh, and Menges 2011; Williams, Sheikh, et al. 2018; Williams and Bligh 2011). Simulation indicated a 34½-in.-tall vertical barrier could result in a successful MASH TL-4 SUT test, but no full-scale crash testing verified this height (Rosenbaugh et al. 2012). Thus, the minimum MASH TL-4 barrier height was recommended to be 36 in., which has been successful for single-slope barriers, vertical barriers, and steel bridge rails. It was unknown if the minimum TL-4 barrier height varied for Jersey and F-shape barriers. The maximum MASH TL-4 steel and concrete barrier heights used by state DOTs were 56 in. and 90 in., respectively. 2.8.4 MASH TL-5 The TL-5 minimum barrier height established in the BDS was 42 in. based on successful full- scale crash testing. Since there were minimal changes between NCHRP Report 350 (Ross et al. 1993) and MASH TL-5 testing criteria, and successful crash tests were conducted on 41.3- and 42-in.-tall concrete barriers with MASH (Buth and Menges 2012; Williams, Bligh, et al. 2018; Buth and Menges 2011), 42 in. was suggested as the minimum barrier height for MASH TL-5, which has been successful for many barrier shapes. The maximum MASH TL-5 steel and concrete barrier heights used by state DOTs were 54 in. and 90 in., respectively.