Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance (2022)

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113   After validation of the modified 1100C vehicle, it was necessary to rerun the MASH-2016 Test 3-10 simulations that were conducted under Chapter 2. All systems for the concrete post- and-beam, deck-mounted metal post-and-beam, and curb-mounted metal post-and-beam con- figurations were impacted with the 1100C vehicle model, which included wheel and suspension failure. The parapet-mounted metal post-and-beam systems were not rerun because the vehicle tire would not engage the bridge rail posts. Computer Simulation Results Test 3-10 Simulation Reruns For each simulation, the impact speed was 62 mph and the impact angle was 25 degrees. The impact location was 3.6 ft. upstream of the centerline of a post in the middle of the impact region. A total of 74 simulations were performed for the bridge rail systems. All simulations ran without error. No additional changes were made to the modified 1100C vehicle model during the simulations. Tables 5.1 and 5.2 present the FE computer simulation results for the concrete post-and-beam systems. Tables 5.3 and 5.4 present the FE computer simulation results for the deck-mounted metal post-and-beam systems. Tables 5.5 and 5.6 present the FE computer simulation results for the curb-mounted metal post-and-beam systems. Compilation of Simulation Results After rerunning the MASH-2016 Test 3-10 computer simulations for the bridge rail systems, the updated results for each bridge rail system were plotted on the snag potential and post setback figures. The results for the MASH-2016 Test 3-11 computer simulations performed in Chapter 2 are also shown in this section. Figures 5.1 and 5.2 show the results for the concrete post-and-beam bridge rail Test 3-10 sim- ulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. Several simulations resulted in occupant risk metrics below the preferred MASH-2016 limits. Figures 5.3 and 5.4 show the results for the concrete post-and-beam bridge rail Test 3-11 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. Several simulations resulted in occupant risk metrics below the preferred MASH-2016 limits. C H A P T E R 5 Final Evaluation of AASHTO Geometric Curves

Bridge Rail System Post Setback Distance (in.) Vertical Clear Opening (in.) Ratio of Contact Width to Height Height (in.) OIV (m/s) RDA (g’s) Pass OIV/RDA Max. Limits? Pass OIV/RDA Preferred Limits?x-dir y-dir x-dir y-dir CPB-SP-System01 1.25 13 0.6061 33 9.6 –9.2 –4.2 –9.1 Yes No CPB-SP-System02 2 13 0.5517 29 9.8 –7.7 –5.9 –8.6 Yes No CPB-SP-System03 3 13 0.5517 29 9.9 –8.1 –4.3 7.5 Yes No CPB-SP-System04 4.25 13 0.5517 29 8.0 –8.9 –2.6 6.1 Yes Yes CPB-SP-System05 4.75 14 0.5172 29 8.4 –9.1 –4.0 6.5 Yes No CPB-SP-System06 5.25 15 0.4828 29 7.0 –8.9 –2.4 5.5 Yes Yes CPB-SP-System07 6 15 0.4828 29 7.3 –8.7 –3.0 5.8 Yes Yes CPB-SP-System08 1.25 10.75 0.6293 29 8.4 –8.7 –5.6 5.4 Yes Yes CPB-SP-System09 2 11.25 0.6121 29 8.8 –8.4 –5.3 6.7 Yes Yes CPB-SP-System10 3 12 0.5862 29 8.5 –8.4 –2.6 8.0 Yes Yes CPB-SP-System11 4.25 12 0.5862 29 8.5 –9.3 3.5 7.5 Yes No CPB-SP-System12 4.75 12 0.5862 29 8.5 –9.3 2.0 7.0 Yes No CPB-SP-System13 5.25 12 0.5862 29 7.9 –8.3 –3.4 8.4 Yes Yes CPB-SP-System14 6 12 0.5862 29 7.3 –9.2 2.6 9.6 Yes No Table 5.1. Concrete post-and-beam results for snag potential cases (Test 3-10). Bridge Rail System Post Setback Distance (in.) Vertical Clear Opening (in.) Ratio of Contact Width to Height Height (in.) OIV (m/s) RDA (g’s) Pass OIV/RDA Max. Limits? Pass OIV/RDA Preferred Limits?x-dir y-dir x-dir y-dir CPB-PS-System01 1.25 13 0.6061 33 9.6 –9.2 –4.2 –9.1 Yes No CPB-PS-System02 2 13 0.5517 29 9.8 –7.7 –5.9 –8.6 Yes No CPB-PS-System03 2.5 13 0.5517 29 7.5 –8.6 –2.8 6.3 Yes Yes CPB-PS-System04 3 13 0.5517 29 8.0 –8.9 –2.6 6.1 Yes Yes CPB-PS-System05 3.5 13 0.5517 29 9.3 –7.7 –7.7 9.9 Yes No CPB-PS-System06 4 13 0.5517 29 8.8 –8.7 –1.7 4.7 Yes Yes CPB-PS-System07 2.5 6.5 0.8030 33 5.4 –9.6 –10.9 20.4 Yes No CPB-PS-System08 3 9 0.7273 33 5.8 –9.7 –5.4 18.0 Yes No CPB-PS-System09 3.5 11 0.6667 33 8.7 –9.1 –6.3 6.6 Yes No CPB-PS-System10 4 11.5 0.6034 29 8.5 –9.3 –3.1 6.9 Yes No CPB-PS-System11 4.5 13 0.5517 29 8.5 –8.7 –2.3 4.5 Yes Yes CPB-PS-System12 5 14.5 0.5000 29 8.6 –8.9 –3.8 8.0 Yes Yes Table 5.2. Concrete post-and-beam results for post setback cases (Test 3-10).

Bridge Rail System Post Setback Distance (in.) 1st Vertical Clear Opening (in.) 2nd Vertical Clear Opening (in.) Ratio of Contact Width to Height Height (in.) OIV (m/s) RDA (g’s) Pass OIV/RDA Max. Limits? Pass OIV/RDA Preferred Limits?x-dir y-dir x-dir y-dir MPBD-SP-System01 3 13 5 0.4000 30 8.3 –9.1 –12.9 9.3 Yes No MPBD-SP-System02 4 13 8 0.3226 31 7.4 –8.9 –7.3 10.1 Yes Yes MPBD-SP-System03 4.5 13.5 7.5 0.3000 30 7.5 –8.7 –5.1 9.0 Yes Yes MPBD-SP-System04 5 14.5 8.5 0.2813 32 6.6 –8.7 –11.9 8.8 Yes Yes MPBD-SP-System05 6 15 7 0.2667 30 6.9 –8.6 6.7 9.7 Yes Yes MPBD-SP-System06 7 15 8 0.2581 31 7.1 –8.7 –7.1 9.8 Yes Yes MPBD-SP-System07 3 12 6 0.4000 30 6.2 –9.4 9.2 15.3 Yes No MPBD-SP-System08 4 12 9 0.3226 31 6.7 –9.1 –3.7 13.4 Yes No MPBD-SP-System09 4.5 12 9 0.3000 30 7.3 –8.9 –4.4 9.9 Yes Yes MPBD-SP-System10 5 12 11 0.2813 32 6.9 –9.5 –3.3 12.6 Yes No MPBD-SP-System11 6 12 10 0.2667 30 7.3 –9.4 –2.6 11.2 Yes No MPBD-SP-System12 7 12 11 0.2581 31 6.8 –8.8 –6.1 11.1 Yes Yes Table 5.3. Deck-mounted metal post-and-beam results for snag potential cases (Test 3-10). Bridge Rail System Post Setback Distance (in.) 1st Vertical Clear Opening (in.) 2nd Vertical Clear Opening (in.) Ratio of Contact Width to Height Height (in.) OIV (m/s) RDA (g’s) Pass OIV/RDA Max. Limits? Pass OIV/RDA Preferred Limits?x-dir y-dir x-dir y-dir MPBD-PS-System01 3 13 5 0.4000 30 8.3 –9.1 –12.9 9.3 Yes No MPBD-PS-System02 4 13 8 0.3226 31 7.4 –8.9 –7.3 10.1 Yes Yes MPBD-PS-System03 4.5 13.5 7.5 0.3000 30 7.5 –8.7 –5.1 9.0 Yes Yes MPBD-PS-System04 5 14.5 8.5 0.2813 32 6.6 –8.7 –11.9 8.8 Yes Yes MPBD-PS-System05 6 15 7 0.2667 30 6.9 –8.6 6.7 9.7 Yes Yes MPBD-PS-System06 7 15 8 0.2581 31 7.1 –8.7 –7.1 9.8 Yes Yes MPBD-PS-System07 3 4 4 0.7333 30 5.5 –9.6 5.1 17.7 Yes No MPBD-PS-System08 4 6 6 0.6000 30 6.2 –9.1 7.4 19.3 Yes No MPBD-PS-System09 4.5 7 7 0.5484 31 5.5 –9.5 2.7 18.8 Yes No MPBD-PS-System10 5 8 7 0.5000 30 6.0 –9.5 2.8 15.5 Yes No MPBD-PS-System11 6 12 10 0.4667 30 6.1 –9.4 –3.7 17.4 Yes No MPBD-PS-System12 7 12 11 0.4333 30 5.9 –9.5 –7.7 15.4 Yes No Table 5.4. Deck-mounted metal post-and-beam results for post setback cases (Test 3-10).

Bridge Rail System Post Setback Distance (in.) 1st Vertical Clear Opening (in.) 2nd Vertical Clear Opening (in.) Ratio of Contact Width to Height Height (in.) OIV (m/s) RDA (g’s) Pass OIV/RDA Max. Limits? Pass OIV/RDA Preferred Limits?x-dir y-dir x-dir y-dir MPBC-SP-System01 3 13 5 0.4000 30 10.0 –9.1 –7.7 –5.5 Yes No MPBC-SP-System02 4 13 8 0.3226 31 8.7 –8.2 –10.9 14.6 Yes Yes MPBC-SP-System03 5 14.5 8.5 0.3030 33 8.3 –8.6 –10.1 –5.6 Yes Yes MPBC-SP-System04 6 15 7 0.3125 32 8.8 –7.6 –12.5 13.9 Yes Yes MPBC-SP-System05 7 15 8 0.3030 33 8.6 –8.3 –8.1 12.1 Yes Yes MPBC-SP-System06 8 15 8 0.3030 33 8.2 –7.9 –7.3 15.4 Yes No MPBC-SP-System07 3 12 6 0.4000 30 9.8 –8.5 –8.9 –10.2 Yes No MPBC-SP-System08 4 12 9 0.3226 31 8.6 –8.6 –11.5 8.4 Yes Yes MPBC-SP-System09 5 12 11 0.3030 33 8.4 –8.9 –12.9 –8.4 Yes Yes MPBC-SP-System10 6 12 10 0.3125 32 7.6 –9.3 –10.3 10.0 Yes No MPBC-SP-System11 7 12 11 0.3030 33 7.9 –9.0 –10.3 8.0 Yes Yes MPBC-SP-System12 8 12 11 0.3030 33 8.0 –8.8 –7.7 8.7 Yes Yes Table 5.5. Curb-mounted metal post-and-beam results for snag potential cases (Test 3-10). Bridge Rail System Post Setback Distance (in.) 1st Vertical Clear Opening (in.) 2nd Vertical Clear Opening (in.) Ratio of Contact Width to Height Height (in.) OIV (m/s) RDA (g’s) Pass OIV/RDA Max. Limits? Pass OIV/RDA Preferred Limits? x-dir y-dir x-dir y-dir MPBC-PS-System01 3 13 5 0.4000 30 10.0 –9.1 –7.7 –5.5 Yes No MPBC-PS-System02 4 13 8 0.3226 31 8.7 –8.2 –10.9 14.6 Yes Yes MPBC-PS-System03 5 14.5 11.5 0.2778 36 9.4 –7.8 –13.5 6.0 Yes No MPBC-PS-System04 6 15 12 0.2703 37 10.2 –8.2 –9.7 7.1 Yes No MPBC-PS-System05 7 15 13 0.2632 38 9.8 –8.3 –8.2 6.2 Yes No MPBC-PS-System06 8 15 14 0.2564 39 8.4 –8.4 –11.1 5.5 Yes Yes MPBC-PS-System07 3 4 4 0.7333 30 5.9 –9.7 –6.6 16.4 Yes No MPBC-PS-System08 4 6 6 0.6000 30 6.0 –9.5 –5.5 16.2 Yes No MPBC-PS-System09 5 8 7 0.5000 30 6.5 –9.6 –6.8 13.6 Yes No MPBC-PS-System10 6 8 8 0.4667 30 6.9 –9.3 –4.3 14.8 Yes No MPBC-PS-System11 7 9 8 0.4333 30 7.1 –9.5 –3.9 13.4 Yes No MPBC-PS-System12 8 9 8 0.4333 30 6.8 –9.6 6.1 11.6 Yes No Table 5.6. Curb-mounted metal post-and-beam results for post setback cases (Test 3-10).

Final Evaluation of AASHTO Geometric Curves 117   0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA High Snag Potential Low Snag Potential Figure 5.1. Test 3-10 snag potential simulation results for concrete post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.2. Test 3-10 post setback simulation results for concrete post-and-beam bridge rails.

118 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Low Snag Potential High Snag Potential Figure 5.3. Test 3-11 snag potential simulation results for concrete post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Figure 5.4. Test 3-11 post setback simulation results for concrete post-and-beam bridge rails. The current AASHTO geometric curves were overlaid on the figures as a reference to under- stand the trend given the MASH data points developed in this project. Figures 5.5 and 5.6 show the results for the deck-mounted metal post-and-beam bridge rail Test 3-10 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. Several simulations resulted in occupant risk metrics below the preferred MASH-2016 limits. Figures 5.7 and 5.8 show the results for the deck-mounted metal post-and-beam bridge rail Test 3-11 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. Several simulations resulted in occupant risk metrics below the preferred MASH-2016 limits.

Final Evaluation of AASHTO Geometric Curves 119   0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Low Snag Potential High Snag Potential Figure 5.5. Test 3-10 snag potential simulation results for deck- mounted metal post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.6. Test 3-10 post setback simulation results for deck- mounted metal post-and-beam bridge rails.

120 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Preferred OIV/RDA Low Snag Potential High Snag Potential Figure 5.7. Test 3-11 snag potential simulation results for deck- mounted metal post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.8. Test 3-11 post setback simulation results for deck- mounted metal post-and-beam bridge rails.

Final Evaluation of AASHTO Geometric Curves 121   0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Low Snag Potential High Snag Potential Figure 5.9. Test 3-10 snag potential simulation results for curb- mounted metal post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.10. Test 3-10 post setback simulation results for curb- mounted metal post-and-beam bridge rails. Figures 5.9 and 5.10 show the results for the curb-mounted metal post-and-beam bridge rail Test 3-10 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. Several simulations resulted in occupant risk metrics below the preferred MASH-2016 limits. Figures 5.11 and 5.12 show the results for the curb-mounted metal post-and-beam bridge rail Test 3-11 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. Several simulations resulted in occupant risk metrics below the preferred MASH-2016 limits.

122 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Low Snag Potential High Snag Potential Figure 5.11. Test 3-11 snag potential simulation results for curb- mounted metal post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.12. Test 3-11 post setback simulation results for curb- mounted metal post-and-beam bridge rails.

Final Evaluation of AASHTO Geometric Curves 123   Figures 5.13 and 5.14 show the results for the parapet-mounted metal post-and-beam bridge rail Test 3-10 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. One simulation resulted in occupant risk metrics below the preferred MASH-2016 limits. Figures 5.15 and 5.16 show the results for the parapet-mounted metal post-and-beam bridge rail Test 3-11 simulations. None of the simulations resulted in occupant risk metrics exceeding the MASH-2016 limits. One simulation resulted in occupant risk metrics below the preferred MASH-2016 limits. 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Max OIV/RDA Low Snag Potential High Snag Potential Figure 5.13. Test 3-10 snag potential simulation results for parapet-mounted metal post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.14. Test 3-10 post setback simulation results for parapet- mounted metal post-and-beam bridge rails.

124 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Pass Preferred OIV/RDA Low Snag Potential High Snag Potential Figure 5.15. Test 3-11 snag potential simulation results for parapet-mounted metal post-and-beam bridge rails. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Pass Max OIV/RDA Pass Preferred OIV/RDA Preferred Not Recommended Figure 5.16. Test 3-11 post setback simulation results for parapet- mounted metal post-and-beam bridge rails.

Final Evaluation of AASHTO Geometric Curves 125   Based on the simulation results, the AASHTO LRFD Section 13 geometric curves can be considered acceptable in their current format for MASH-2016 evaluation criteria. Rerunning the Test 3-10 simulations with the modified 1100C vehicle model resulted in no simulations with occupant risk values exceeding the MASH limit. However, some noteworthy trends were identi- fied for both geometric figures after reviewing all the 3-10 and 3-11 computer simulation results. First, there were many bridge rail configurations with large vertical clear openings that resulted in occupant risk metrics below the MASH-2016 preferred limits. This was true for both the small car and pickup truck computer simulations. Previous testing under NCHRP Report 230 and NCHRP Report 350 had shown these large clear openings to allow significant snagging and result in high occupant risk values. Additionally, there were several bridge rail configurations with small clear openings that resulted in occupant risk values just below the MASH-2016 max- imum limits. Second, there were many bridge rail configurations with small ratios of rail contact width to height that resulted in occupant risk values below the MASH preferred limits. Also, there were several bridge rail configurations with large ratios of rail contact width to height that resulted in MASH-2016 occupant risk metrics just below the MASH maximum limits. This trend appears to be the opposite of the current AASHTO LRFD Section 13 post setback figure, which identifies bridge rail systems with large ratios of rail contact width to height as preferred. To further investigate these trends and information, a review of full-scale crash testing of MASH-2016 bridge rail systems was conducted. MASH Crash-Test Data A review of full-scale crash tests performed on various bridge rail systems was conducted. A total of 28 bridge rail systems were reviewed and compiled based on bridge rail geometrics and MASH-2016 occupant risk results. The bridge rail systems were plotted on the AASHTO LRFD Section 13 snag potential and post setback figures and categorized based on passing the MASH-2016 preferred limits or MASH-2016 maximum limits. Figures 5.17 and 5.18 show the MASH-2016 Test 3-10 full-scale crash tests. There was only one system that resulted in occupant risk values below the MASH-2016 preferred values. As such, this offered little insight into potential trends in these figures. Figures 5.19 and 5.20 show the same bridge rail systems but with different occupant risk categories. One category of data points shows all bridge rail systems with an OIV less than 34 ft./s and an RDA less than 17 g’s. The other category shows the bridge rail systems above the previous threshold and less than 40 ft./s and 20 g’s. Figures 5.21 and 5.22 show the bridge rail systems with MASH Test 3-11 full-scale crash tests. Based on the data in Figures 5.19 through 5.22, bridge rail systems with smaller ratios of rail contact width to height and larger vertical clear openings tend to have lower occupant risk values than bridge rail systems with larger ratios of rail contact width to height and smaller vertical clear openings. There are some bridge rail systems that do not follow this trend. The general trends identified in the computer simulations and the full-scale crash tests show bridge rail systems with smaller ratios of rail contact width to height and larger vertical clear open- ings led to lower MASH-2016 occupant risk values. The current AASHTO LRFD Section 13 post setback figure “preferred” and “not recommended” regions may be misleading to this trend as it may be thought that a bridge rail system with preferred geometrics would result in lower occupant

126 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Preferred Max Figure 5.17. MASH-2016 Test 3-10 snag potential full-scale crash test data. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.00 2.00 4.00 6.00 8.00 10.00 12.00 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Preferred Max Figure 5.18. MASH-2016 Test 3-10 post setback full-scale crash test data. risk values. The computer simulations and full-scale crash tests have shown this not to be the case. The same is generally true for the current AASHTO LRFD Section 13 snag potential figure. As such, it may be beneficial to modify the curves and provide one singular line for each figure. This line would recommend bridge rail geometrics that result in passing MASH-2016 occupant risk criteria and not recommend bridge rail geometrics that result in failing MASH-2016 occu- pant risk criteria. The next section will explore modifying the geometric figures and identifying a single curve.

Final Evaluation of AASHTO Geometric Curves 127   0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) OIV < 34 ft/s and ORA < 17 g's Max Figure 5.19. MASH-2016 Test 3-10 snag potential full-scale crash test data—modified limits. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) OIV < 34 ft/s and ORA < 17 g's Max Figure 5.20. MASH-2016 Test 3-10 post setback full-scale crash test data— modified limits.

128 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Preferred Max Figure 5.21. MASH-2016 Test 3-11 snag potential full-scale crash test data. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Preferred Max Figure 5.22. MASH-2016 Test 3-11 post setback full-scale crash test data.

Final Evaluation of AASHTO Geometric Curves 129   0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Proposed Curve Simulation Cases Figure 5.23. Snag potential bridge rail simulation cases to evaluate new curve. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Proposed Curve MASH Simulations Figure 5.24. Post setback bridge rail simulation cases to evaluate new curve. Evaluation of New Geometric Curves A group of new bridge rail configurations were identified to develop a new curve on the current geometric figures. These curves would separate regions on these figures based on satis- factory or unsatisfactory MASH-2016 occupant risk results. Figures 5.23 and 5.24 show the bridge rail geometric curves with the new configurations. For each bridge rail configuration, Test 3-10 and 3-11 impacts were simulated. The current geometric curves were left on the

130 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance figures as a reference point. These bridge rail configurations included concrete post-and-beam, deck-mounted metal post-and-beam, and curb-mounted metal post-and-beam systems. Each bridge rail simulation was post-processed to determine MASH-2016 occupant risk values. Figure 5.25 shows the results for the simulation cases with the snag potential curve. There were three bridge rail systems that resulted in occupant risk values exceeding the MASH-2016 limits. Thus, additional bridge rail systems were configured with small vertical clear openings and eval- uated for MASH-2016 compliance. Figure 5.26 shows the results for the simulation cases with the post setback curve. All simu- lations resulted in occupant risk values below the limit. Additional bridge rail configurations 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Proposed Curve Pass MASH Fail MASH Figure 5.25. Snag potential simulation results for new curve evaluation. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Proposed Curve Pass MASH Figure 5.26. Post setback simulation results for new curve evaluation.

Final Evaluation of AASHTO Geometric Curves 131   below the proposed curve were not considered. The geometrics for these systems would not be representative of a practical bridge rail system. Also, several of the simulations along the pro- posed curve resulted in occupant risk values near the MASH-2016 limit, so the proposed curve appears to be capturing the regions well. After completing the simulations, the curves were modified to adjust for the failed systems. Figures 5.27 and 5.28 show the final proposed curves for bridge rail geometrics. 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Recommended Not Recommended Figure 5.27. Final proposed snag potential curve. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 2 4 6 8 10 12 Ra tio o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Recommended Not Recommended Figure 5.28. Final proposed post setback curve.

132 Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance Assessment of NCHRP Project 20-07 Marginal Bridge Rail Systems In Silvestri-Dobrovolny et al. (7), six bridge rail systems received a marginal rating based on their geometrics. The marginal rating was based on insufficient data on bridge rail systems that plotted in the region between the two curves on the AASHTO geometric figures. One system also received a not satisfactory rating for geometrics. Figures 5.29 and 5.30 show the bridge rail Wyoming Two-Tube 36d Bridge Rail Nebraska Open Concrete Bridge Rail Mass. S3-TL4 Bridge Rail Maine Four-Bar Bridge Rail George Washington Memorial Parkway Bridge Rail New Mexico Side- Mounted Bridge Rail Wyoming Two-Tube 36c Bridge Rail 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 2 4 6 8 10 12 R at io o f R ai l C on ta ct W id th to H ei gh t Post Setback Distance (in.) Recommended Not Recommended Figure 5.30. Silvestri-Dobrovolny et al. bridge rails post setback evaluation. Wyoming Two-Tube 36d Bridge Rail Nebraska Open Concrete Bridge Rail Mass. S3-TL4 Bridge Rail Maine Four-Bar Bridge RailGeorge Washington Memorial Parkway Bridge Rail New Mexico Side- Mounted Bridge Rail Wyoming Two-Tube 36c Bridge Rail 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 V er tic al C le ar O pe ni ng (i n. ) Post Setback Distance (in.) Not Recommended Recommended Figure 5.29. Silvestri-Dobrovolny et al. bridge rails snag potential evaluation.

Final Evaluation of AASHTO Geometric Curves 133   systems plotted on the new geometric curves. Using the new recommended geometric curves, the following bridge rail systems should receive a satisfactory rating based on their geometrics: • Two-tube railing 36d (Wyoming) • Two Tube TL-3 SBB36c (Wyoming) • Open concrete rail with 2-ft.-10-in. height (Nebraska) • S3-TL4 (Massachusetts) • Four-bar steel traffic/bicycle railing (on curb; Maine) • George Washington Memorial Parkway (Federal Lands) • Side-mounted metal bridge railing (New Mexico) According to the method presented in Silvestri-Dobrovolny et al., these bridge rail systems would now receive an overall satisfactory rating, so they should now be considered acceptable under the evaluation criteria of MASH-2016. Appendix H presents profile views for each bridge rail system. It should be noted that the Kansas Corral bridge rail system also had a marginal geometric rating but was considered not satisfactory for the strength assessment in Silvestri-Dobrovolny et al. Detailed computer simulations were conducted to further evaluate the structural adequacy of that system. The results of the analysis are provided in Appendix C. Based on the simulation results, this bridge rail system is recommended to be evaluated through full-scale crash testing to adequately evaluate its strength.