| TTI Research Supervisor: Nathan D. Schulz Assistant Research Scientist Texas A&M Transportation Institute Texas A&M University System TAMU 3135 College Station, Texas, 77843-3135 (979) 317-2694 [email protected] | Pooled Fund Technical Representative: Dean Kanitz, P.E. Statewide Freeway Signing Engineer Michigan Department of Transportation 425 W. Ottawa St. Lansing, MI 48909 (517) 335-2855 [email protected] |
The American Association of State Highway and Transportation Officials (AASHTO) recently published an updated 2016 edition of the Manual for Assessing Safety Hardware (MASH) document. Along with this, the Federal Highway Administration (FHWA) and AASHTO developed a revised joint implementation agreement which establishes dates for discontinuing the use of safety hardware that has met earlier crash testing criteria for new installations and full replacements on the National Highway System (NHS). Although some barrier testing was performed during the development of the updated criteria, many barrier systems and other roadside safety features have yet to be evaluated under the proposed guidelines.
Sign support systems were developed and investigated according to Test Level 3 criteria per previous NCHRP Report 350 standard requirements. These systems have not been evaluated and crash tested under the current MASH 2016 Test Level 3 standard criteria.
The purpose of this research is to evaluate a non-proprietary sign support system under MASH 2016 Test Level 3 testing and evaluation criteria. A critical configuration of the sign support system to be considered for full-scale crash testing will be selected through engineering analysis. Engineering opinion will be provided for less critical configurations of the sign support system.
The information compiled from this research will provide the FHWA and State Departments of Transportation with an acceptable sign support system under MASH 2016 Test Level 3 conditions. This system can be used to replace current NCHRP Report 350 systems installed on roadways.
The purpose of this research is to develop a non-proprietary sign support system for MASH 2016 TL-3. The system will be evaluated under MASH 2016 TL-3 crash testing and evaluation criteria.
There are numerous configurations of sign support systems that are used on national roadways to communicate information to the traveling public. It is not cost-effective to perform crash testing for every configuration. Thus, it is necessary to evaluate the critical or worst-case configuration. Engineering analysis will aid in the selection of the critical configuration. Engineering opinion will be provided for other less-critical configurations based upon the successful crash testing performed on the selected critical sign support configuration.
If the results of the full-scale crash tests are deemed successful per MASH 2016, this study will culminate with a request for an FHWA eligibility letter for the tested sign support configuration.
A successful transition design will provide a method for connecting PCBs to guardrails
The information compiled from this research will provide the Federal Highway Administration and State Departments of Transportation with an acceptable non-proprietary sign support system under MASH 2016 TL-3 conditions. A successful non-proprietary sign support system can be used across state roadways in situations where NCHRP Report 350 sign support systems are currently being utilized. The device will be based on previously developed devices for NCHRP Report 350, which will allow installation and maintenance crews to maintain familiarity with the use of these devices.
The TTI research team will provide composite video and photographic documentation of the crash tests and a final report documenting the research and testing performed. If applicable, the TTI research team will provide documentation needed to request FHWA’s acceptance of the non-proprietary sign support system for use on the NHS.
The TTI research team will further provide drawings of the sign support system and each of the components of the system in the format required for inclusion in hardware standards documents of the AASHTO-ATRBA-AGC Task Force 13.
The TTI research team will perform a literature review of sign support systems that have been considered and tested in the past. The TTI research team will give particular relevance to u-channel and perforated square steel tube (PSST) systems. In addition, the TTI research team will conduct a survey of the Roadside Safety Pooled Fund states to gather information on sign standard practices and usage of u-channel and PSST systems. Depending on state responses, the TTI research team will select the higher prioritized system for evaluation and testing under this study.
There are many possible configurations of a sign support system. This includes variations in sign area, post weight, and mounting height. As such, it is not feasible to evaluate every possible configuration of a sign support system with full-scale crash testing. The TTI research team will perform engineering analysis to select the critical sign support for full-scale crash testing. First, the TTI research team will utilize previous testing and evaluation efforts on sign support systems to determine a critical sign support configuration. For example, a previous study by Silvestri et al. showed that sign support systems with smaller sign areas can lead to severe deformation of the vehicle windshield and roof in full-scale crash tests (4). Second, the TTI research team will evaluate the selected critical sign support configuration for structural adequacy under wind, snow, and other sign loading requirements.
The TTI research team will perform six full-scale crash tests on the sign support system according to MASH 2016 TL-3. Two full-scale tests will involve a 2,420-lb passenger car impacting the sign support system at 19 mph nominal speed with the face of the sign oriented at 0° and 90° relative to the vehicle impact path. Two full-scale tests will involve a 2,420-lb passenger car impacting the sign support system at 62 mph nominal speed with the face of the sign oriented at 0° and 90° relative to the vehicle impact path. Two full-scale tests will involve a 5,000-lb passenger car impacting the sign support system at 62 mph nominal speed with the face of the sign oriented at 0° and 90° relative to the vehicle impact path.
The TTI research team will assess the crash tests according to the evaluation criteria set in MASH 2016 standards.
The TTI research team will generate a final report of the findings from the research and testing study. Results will be reported in terms of sign support system performance, vehicle stability, and occupant risk factors and will be compared with respect to MASH 2016 crashworthiness criteria. The TTI research team will further provide drawings of the sign support system and of each of its components in the format required for inclusion in hardware standards documents of the AASHTO-ATRBA-AGC Task Force 13.
If the results of the full-scale crash tests are deemed successful per MASH 2016 evaluation criteria, this study will culminate with a request for an FHWA eligibility letter for the critical sign support system.
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2022-03-03