ATTACHMENT TO BTS LETTER - Transportation



AASHTO STANDING COMMITTEE ON RESEARCH

AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS

NCHRP Problem Statement

I. PROBLEM NUMBER

To be assigned by NCHRP staff.

II. PROBLEM TITLE

Development of Guidelines for the Selection and Placement of Test Levels 2 through 5 Median Barriers

III. RESEARCH PROBLEM STATEMENT

The crash test procedures for median barriers has seen much progress in the last four years as evident by the publication of NCHRP 230, NCHRP 350 and most recently the 2009 AASHTO Manual for Assessing Safety Hardware (MASH). Objective guidance for the implementation of crash tested median barriers, however, have been lacking. In 2009, the TRB published NCHRP Report 638 which provided guidance for the selection of roadside longitudinal barriers. NCHRP Project 22-12(03) is nearing completion and will provide guidelines for the selection of Test Level 2 through Test Level 5 Bridge Railings. Guidance on the selection and placement of median barriers is lacking.

Currently the AASHTO Roadside Design Guide (RDG) is the only National guideline available for states that choose not to prepare their own guidelines for roadside design. The RDG offers subjective guidance for the selection of median barriers, citing a higher percentage of heavy trucks in the traffic flow, adverse geometries, and higher accident rates as conditions that may warrant barriers with a performance level higher than Test Level 3, however thresholds for these values are not provided. Objective guidance on the selection and placement of median barriers would complement recently develop objective guidance for barriers and bridges and would help define these subjective thresholds while helping to balance public funds with improved safety.

IV. LITERATURE SEARCH SUMMARY

A truck-tractor semitrailer was traveling south on Interstate 65 when it departed the left lane and crossed a 60-foot-wide depressed median on March 26, 2010, near Munfordville, Kentucky, The truck struck and overrode the high-tension median cable barrier then entered northbound I-65 and was struck by a 15-passenger van, containing 12 people. Eleven people were fatally injured, two children had minor injuries. As a result of this crash, the National Transportation Safety Board (NTSB) has issued several recommendations about selecting the appropriate test level median barriers for the traffic mix and developing objective warrants for the placement of median barriers. A complete summary of the NTSB investigation is available at this link: . The following recommendations were a result of this investigation:

To the Federal Highway Administration:

Work with the American Association of State Highway and Transportation Officials to establish warrants and implementation criteria for the selection and installation of Test Level Four and Test Level Five median barriers on the National Highway System. (H-11-21)

Work with the American Association of State Highway and Transportation Officials to identify cross-median crash rates that call for special consideration when selecting median barriers. (H-11-22)

Work with the American Association of State Highway and Transportation Officials to define the criteria for median barrier selection, including heavy vehicle traffic volume. (H-11-23)

To the American Association of State Highway and Transportation Officials:

Work with the Federal Highway Administration to establish warrants and implementation criteria for the selection and installation of Test Level Four and Test Level Five median barriers on the National Highway System, and publish those warrants and criteria in the Roadside Design Guide. (H-11-31)

Work with the Federal Highway Administration to identify cross-median crash rates that call for special consideration when selecting median barriers, and publish the rates in the Roadside Design Guide. (H-11-32)

Work with the Federal Highway Administration to define the criteria for median barrier selection, including heavy vehicle traffic volume, and publish the criteria in the Roadside Design Guide. (H-11-33)

A literature search conducted using TRIS Online found only few articles that have been published in the last 10 years that have been related to "median barrier warrants,” however, none of these articles were related to objective guidance for the placement and/or selection of median barriers. There is other recent research on median cross-section design, cable median barriers specifically, and barrier performance in general which will provide needed background for the development of the objective selection tables. A sample of this recently completed and ongoing research is shown here:

• NCHRP 22-12(03), Recommended Guidelines for the Selection of Test Level 2 through 5 Bridge Railings nearing completion. This research effort reviewed the capacity of various rigid barriers and collected crash data to determine the probability of penetrating and rolling over the barrier.

• NCHRP 22-27, Update to the Roadside Safety Analysis Program, completely recoded RSAP and added new methods to specifically analyze the probability of crossing a median both when barrier is and is not present.

• NCHRP Project 22-21, Median Cross-section Design for Rural Divided Highways, which intends to develop median cross-section design guidelines for rural divided highways using both crash-based and vehicle dynamics simulations studies.

• NCHRP 22-22 Placement of Traffic Barriers on Roadside Slopes, which is to produce comprehensive recommendations for placement of barriers on roadside and median slopes using a combination of simulations and crash testing procedures. This research will not, however, address the test level of the barriers.

• Ray et al. reviewed the states’ experiences with cable median barrier, the performance of the barrier, and design policies in “Experience With Cable Median Barriers in United States: Design Standards, Policies and Performance,” Journal of Transportation, American Society of Civil Engineers, October 2009. This paper focused solely on cable median barriers and found that while cable does reduce cross median crash rates, it is still penetrated and not idle for every situation.

• Chen et al. synthesized existing literature on the “Use of Barriers in Rural Open Road Conditions--A Synthesis Study.” (2012).

V. RESEARCH OBJECTIVE

Median barriers can be divided into test levels, as defined by MASH, which represented the type of vehicle the barrier it designed to redirect. Each test level has three general categories, namely flexible, semi-rigid and rigid. The less rigid a barrier is the less energy is required to be dissipated by the vehicle; hence accelerations imparted to the occupants inside the vehicle during an impact are lower with respect to such barriers when compared to rigid barriers. On the other hand, flexible barriers have been shown to have large deflections making these barriers ineffective choices for narrow medians.

The guidelines will be based on traffic volumes, roadway geometry, median slopes, median placement, and barrier type (i.e., shape, material, rigidity, etc.).

It is anticipated that this research would develop charts with associated site specific adjustment factors for the selection of the appropriate test level median barrier. Different charts will likely be developed for the selection of median barrier type and placement in the median. It is anticipated the results will be integrated into the AASHTO Roadside Design Guide.

The accomplishment of these objectives will likely include the following tasks:

a. Perform a criteria review of the published literature.

b. Conduct a survey of the states to collect existing policies.

c. Based on the results of the literature review and survey, suggest a series of alternative median barrier test levels and material types to be evaluated using the third version of the Roadside Safety Analysis Program’s risk analysis protocol developed and documented under NCHRP 22-12(03).

d. Identify crash data which can be used to develop Effective Fatal Crash Cost Ratios for use in the risk-analysis of each alternative under consideration.

e. Submit a Phase I interim report and meet with the panel to review the findings of the report, and the suggested alternatives for consideration.

f. .Execute Phase II to develop guidelines for the selection and placement of median barriers.

g. Solicit feedback from the TCRS and other agencies suggested by the panel. The concerns of the reviewers would be captured and, in conjunction with the panel, decisions made about modification to the guidelines.

h. Prepare the final report

VI. ESTIMATE OF PROBLEM FUNDING AND RESEARCH PERIOD

Recommended Funding: $300,000

Research Period: 36 months

VII. URGENCY, PAYOFF POTENTIAL, AND IMPLEMENTATION

This research will lead to the updating of the median barrier chapter of the Roadside Design Guide, assisting designers in selecting median barriers for installation on existing or planned divided highways. The TRB Committees on Roadside Design, Geometric Design and Operational Effects of Geometrics jointly sponsor this research needs statement.

VIII. PERSON(S) DEVELOPING THE PROBLEM

Joseph G. Jones, P.E.

Missouri Department of Transportation

102 West Capitol Avenue

Jefferson City, MO 65102

E-mail: joseph.jones@modot.

Phone: (573) 751-3813

Christine Carrigan, Ph.D., P.E.

Road Safe, LLC

Box 312, 12 Main St.

Canton, ME 04221

E-mail: Christine@

Phone: (207)513-6057

IX. PROBLEM MONITOR

Joseph G. Jones, P.E.

Missouri Department of Transportation

102 West Capitol Avenue

Jefferson City, MO 65102

E-mail: joseph.jones@modot.

Phone: (573) 751-3813

Keith A. Cota, P.E.

Chairman, Technical Committee on Roadside Safety

New Hampshire DOT

7 Hazen Drive, PO Box 483

Concord, NH 03302-0483

Phone: 603-736-8811

Email: kcota@dot.state.nh.us.

X. DATE AND SUBMITTED BY

August 16, 2013

Keith A. Cota, P.E.

Chairman, Technical Committee on Roadside Safety

New Hampshire DOT

7 Hazen Drive, PO Box 483

Concord, NH 03302-0483

Phone: 603-736-8811

Email: kcota@dot.state.nh.us.

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