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Page 65
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
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Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
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Page 67
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
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Page 68
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
Page 68
Page 69
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
Page 69
Page 70
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
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Page 71
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
Page 71
Page 72
Suggested Citation:"Appendix A - Survey of States." National Academies of Sciences, Engineering, and Medicine. 2022. Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers. Washington, DC: The National Academies Press. doi: 10.17226/26679.
×
Page 72

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A-1   A P P E N D I X A Survey of States This research includes the conduct of two surveys. A survey of the AASHTO Highway Subcommittee on Design (SCOD) Technical Committee on Roadside Safety (TCRS) members and the 50 states was conducted to identify current policies or practices for the selection and placement of median barriers. A second survey was distributed to the TCRS to receive input on the study protocol. The SCOD survey results are summarized here. The TCRS survey results were used to develop the research protocol and guide this research effort. CONTENTS Chapter 1 Introduction Chapter 2 SCOD Survey Question 1: Changes Since 2006 Question 2: Typical Median Cross Section Question 3: Median Barrier Criteria Question 4a and b: Median Barrier Need Question 5a, b, and c: Median Barrier Type and Placement Question 6: Median Barrier Type and Placement Question 7: Ditch Width, Slopes, and Depth Question 8: ISPEs Chapter 3 Summary

A-2 Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers CHAPTER 1 INTRODUCTION This research included the conduct of two surveys. A survey of the AASHTO Highway Subcommittee on Design (SCOD) Technical Committee on Roadside Safety (TCRS) members and the 50 states was conducted to identify current policies or practices for the selection and placement of median barriers. A second survey was distributed to the TCRS for input on study protocol. The SCOD survey results are summarized here. The TCRS survey results were used to develop the research protocol and guide this research effort.

Survey of States A-3   CHAPTER 2 SCOD SURVEY The purpose of this survey was to gather information on the current practices, policies, and procedures used throughout the United States for median design and median barrier use. This survey served as an update to a previous survey conducted in 2006 as documented by Graham et al. in NCHRP Report 794. (Graham 2014) The survey was distributed to the AASHTO SCOD on March 29, 2016. The results, summarized herein, were current as of April 29, 2016. Question 1: Changes Since 2006 At the onset of this survey, the survey participants were notified that this survey was an update of the survey conducted in 2006, and they were asked if there were any changes to their state’s policies since that time. If the respondent indicated that the 2006 responses were still current, the respondent was directed to the end of the survey and thanked for their time. Otherwise, the respondent was taken through the survey questions. Twenty-six individuals viewed this question. Two skipped the question, while 24 responded. The exact wording of the question, answer options, and response counts are shown in Table A-1. Seventeen respondents (more than two-thirds) indicated that they either did not participate in the previous survey or did participate but their policies have changed in the interim. Table A-1 Question One Summary This survey was previously conducted in 2006. If your policies concerning median cross section and median barrier use have NOT changed since 2006, simply indicate "No Change" below. Response Percent Response Count A ns w er O pt io ns No change. The 2006 responses are still current. 29.2% 7 Policies or practices have changed since 2006. 29.2% 7 Did not respond to the 2006 survey. 41.7% 10 Answered question 24 Skipped question 2

A-4 Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers Question 2: Typical Median Cross Section The survey participants were asked to indicate their agency’s typical cross section for medians on divided highways. Thirteen respondents provided feedback on this question while 13 respondents skipped it. The responses for median width varied considerably among the respondents who answered Question 2. Rural freeways were reported to have a typical width ranging from 36 to100 feet and urban freeways have a typical width ranging between 10 to 50 feet. Other roadways were reported to have a typical width between 4 to 80 feet depending on the design speed. Conversely, the reported median slopes were rather consistent with typical values equal to 6H:1V with 4H:1V permitted. One respondent indicated the 10H:1V is typical and two indicated that 8H:1V is typical. Respondents specifically noted that when median barriers are in use, typical median widths are narrower. Some respondents also noted it is difficult to characterize medians by typical values. The cross-section values from this survey are consistent with values reported in 2014 by Graham et al. in NCHRP Report 794: Median Cross-Section Design for Rural Divided Highways. Question 3: Median Barrier Criteria The survey participants were asked if their agency references the 2002 AASHTO Roadside Design Guide (RDG) Figure 6-1 criterion to evaluate the need for median barriers or if something else is referenced (e.g., 2006 RDG). Fourteen respondents answered this question while 12 respondents skipped it. Seven responses indicated that the 2002 AASHTO RDG is referenced. One indicated the 2006 RDG is referenced. Three indicated the 2011 RDG is referenced. The three other states reported having state-specific policies in place. The responses are shown graphically in Figure A-1. The findings reported by Graham et al. in NCHRP Report 794 in 2014 were from a survey conducted in 2006. Not surprisingly, none of the respondents to the Graham et al. survey used the 2006 AASHTO RDG in 2006. As indicated by the responses to this survey, in 2016, many States continued to use the 2002 AASHTO RDG figures to evaluate the need for median barriers. Figure A-1 Responses for median barrier guidance source material. 0 1 2 3 4 5 6 7 8 2002 RDG 2006 RDG 2011 RDG State-Specific Policies

Survey of States A-5   Question 4a and b: Median Barrier Need The survey participants were asked which criteria are considered and the corresponding quantitative values to assess the need for median barriers for divided highways. Ten respondents answered this question while sixteen respondents skipped it. The responses listed a variety of median widths ranging from 36 feet to 64 feet, for which a barrier is provided (i.e., median width is a criterion for installation of a median barrier). Additionally, barriers are commonly provided by the respondents on divided highways with traversable narrow medians where the traffic volume was equal to or greater than 20,000 vehicles per day. Other factors considered by the respondents included: • Crash history; • Speed; • Highway curvature; • Clear zone issues including slopes; • Highway type (e.g., median barrier required on all freeways); • Agency experience; and/or • New construction versus retrofit. Question 5a, b, and c: Median Barrier Type and Placement Ten respondents provided feedback on the median barrier types that are currently approved for use on divided highways, the minimum median width (ft) required for the approved barrier, the most common placement location, the maximum median side slope for installation, and the percent usage of each of the approved barrier types. Comments were not received for weak-post w-beam median barrier or modified thrie- beam median barrier. One respondent offered that box-beam median barrier is used in medians with a width of 36 feet and 10:1 slope. The box-beam barrier is located three feet from the shoulder. This state’s inventory is approximately 40% box-beam. Three-strand weak-post cable median barrier is typically installed in medians having a width ranging from 30 to 46 feet with a slope of 6:1 or flatter. The three-strand weak-post cable is installed either at the center of the median or four feet from the center. High-tension cable was found to be installed in medians with widths of 15 to 40 feet. One state ensures the median is wide enough to accommodate the barrier deflection plus 50%. The high-tension cable is in medians with slopes of 10:1, 6:1, or 4:1 at the center of the median or offset eight feet from the centerline of the median ditch. States reported having a high-tension cable median barrier inventory of 5%, 10%, 16%, or 25%. Blocked-out strong-post w-beam median barrier was found to be installed in medians with widths of 6 to 46 feet. One state reported using it exclusively for median clear zone issues. The strong-post w-beam is installed in medians with slopes of 10:1, 8:1, or 6:1 at a variety of locations, including: • 6 feet from the edge of the travel lane; • 2 feet from the outside shoulder; • 12 feet from the edge of the travel lane; • Center of median or at shoulder edge on curves; • • 4 feet from edge of pavement; or At slope break, beyond the edge of the paved shoulder.

A-6 Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers The states responding with use of strong-post w-beam median barrier indicated the inventory was either 20% or 70% to 80%. A few states reported using blocked-out thrie-beam median barriers in medians 6 to 30 feet wide with a slope of 6:1. The barrier is located at the center of the median and represents 10% of the inventory in states that use it. F-shaped, single-slope, and New Jersey-shaped concrete median barriers were reported to be used in medians wide enough to accommodate the barrier and shoulder widths. These concrete median barriers are consistently located at the center of the median. The estimated usage for each barrier was reported to have the following range: • F-shaped concrete barrier: 5% to 43% • Single-slope concrete barrier: 13% to 50% • New Jersey-shaped concrete barrier: 5% to 25% Question 6: Median Barrier Type and Placement The survey participants were asked if their state maintains a barrier asset inventory and if the inventory could be made available for the research effort. Six survey respondents answered in the affirmative by providing email contact information for their state’s inventory point of contact. The States of Arkansas, Tennessee, Ohio, Maine, Wyoming, and Arizona provided contact information to obtain the asset inventory for use in this effort. Question 7: Ditch Width, Slopes, and Depth Participants in the survey were asked to provide the typical values used in their state for ditch width, slope, and depth. Twelve respondents answered this question in part or whole while fourteen respondents skipped it. Understandably, the answers to this question received some varied responses; summaries are provided below: • Ditch widths reported included: 20, 30, 34, 40, 46, 50, 60, and 84 feet. • The typical ditch slope values reported were 4:1, 6:1, and 8:1. • Most respondents reported ditch depths of one to five feet. One respondent commented that the ditch depth can become much greater in some cases. Question 8: ISPEs The survey participants were asked if their agency had made in-service performance evaluations (ISPEs) to study the safety performance of various median designs or medium barriers. Three ISPEs were made available.

Survey of States A-7   CHAPTER 3 SUMMARY The purpose of this survey was twofold: (1) to track changes in policy over time and (2) to compile existing practices concerning the selection and placement of median barriers. One- third of the states that responded have not changed their practices since 2006, which reflects the adoption rate of the last update to the RDG. Respondents to this survey were clear that median designs vary considerably within a state and vary more between states. This survey compiled information on the current practices concerning median design and median barrier use. It was found that median widths vary from 30 to 100 feet and median slopes vary between 4:1, 6:1, 8:1, and 10:1. Over time, the existing practice for the assessment of median barrier needs has come to consider the following: • Crash history, • Speed, • Highway curvature, • Clear zone issues including slopes, • Highway type, • Agency experience, and/or • New construction versus retrofit.

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The variety of median widths and terrains combined with evolving testing specifications and lack of conclusive data on median crossover crashes have been obstacles to developing median barrier guidance.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 996: Selection and Placement Guidelines for Test Level 2 Through Test Level 5 Median Barriers develops, in a format suitable for consideration and possible adoption by AASHTO, proposed guidelines for the selection and placement of Manual for Assessing Safety Hardware (MASH) Test Levels 2 through 5 (TL2-TL5) median barriers.

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