|TTI Research Supervisor:|
Nauman Sheikh, P.E.
Assistant Research Engineer
Texas Transportation Institute
Texas A&M University System
College Station, Texas 77843-3135
|Pooled Fund Technical Representative:|
Traffic and Safety Division
Utah Depart. of Transportation
4501 South 2700 West
PO Box 143200
Salt Lake City UT 84114-3200
Many states install portable concrete barriers (PCB) in permanent applications that require the last three barrier segments to be anchored before installing a W-beam guardrail transition. Site conditions at such installations often have narrow shoulders and drop offs behind the barrier, making it difficult to flare the barrier systems, as recommended in some available design options for attaching guardrail transitions to anchored barrier segments.
Due to the presence of narrower shoulders and drop offs, there is a need to attach the guardrail transition to tangent anchored barrier segments, without flaring the PCB system. At this time there are no transitions between W-beam or thrie-beam guardrail to anchored PCBs that are compliant with American Association of State Highway and Transportation Official’s (AASHTO) Manual for Assessing Safety Hardware (MASH).
The purpose of this research is to design and test a transition between W-beam guardrail and tangent anchored PCBs with F-shape profile, meeting the safety performance criteria of Test Level 3 (TL-3) of MASH.
A successful transition design will provide a method for connecting PCBs to guardrails in a safe and MASH compliant manner. Transitioning concrete barriers to W-beam guardrail allows installing a MASH compliant end terminal at the end of the system. This protects the motoring public from hitting the blunt end of an unprotected concrete barrier.
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.
Caltrans will be able to develop state standard provide design details of the anchored PCB and its various applications.
The TTI research team proposes the following work plan tasks to meet the project objectives.
The TTI research team will develop various concepts of the transition from W-beam guardrail to anchored F-shape PCB. The TTI research team will present the concepts to the Technical Representative for selection of one concept for further development through simulation and full-scale testing.
The TTI research team will develop full scale model of the transition concept and will perform impact simulations with MASH TL-3 conditions to determine the performance of the design. The TTI research team will perform simulations for impact conditions of MASH Test 3-20 (small car) and Test 3-21 (pickup truck). The TTI research team will use the results of the simulation to make relatively small modifications to the design to improve its performance. The TTI research team will also use simulation analyses to determine the critical impact points (CIP) for crash testing.
The TTI research team will construct a full-scale test installation of the anchored F-shape barrier and the guardrail transition.
The TTThe TTI research team will perform MASH Test 3-21 and Test 3-20 at the downstream end of the transition. It is assumed that the upstream end of the transition can be kept the same as one of the existing guardrail transitions that have previously passed MASH. Doing this will not require testing at the upstream end of the transition. However, if this cannot be achieved, additional testing may be required at the upstream end, which will require allocating more resources to the project, or by completing the upstream testing in a second phase. The TTI research team will prepare a final project report after completion of the crash testing.