Development of a Low-profile to F-shape Transition Barrier Segment


Book Description

The purpose of the research reported herein was to develop a transition barrier segment that can be used to connect the low-profile barrier (LPCB(1)-92) to the standard height, F-shape portable concrete barrier (CSB-04). The design of the new transition barrier segment is such that no new hardware is required to connect the transition barrier segment to the low-profile barrier and the F-shape barrier. Researchers used computer simulations to evaluate the proposed design and to examine the location of critical impact points that were used in specifying impact conditions for a full-scale evaluation of the new design. Results of two full-scale tests coupled with results from the computer simulations show that the new transition barrier segment is ready for immediate implementation.







Development of MASH TL-3 Transitions for Cast in Place Concrete Barriers


Book Description

The objective of this project was to develop transition designs for three cast in place concrete barrier combinations. These included transitions for connecting (a) TxDOT's 36-inch tall Single Slope Traffic Rail (SSTR) to 42-inch tall Single Slope Concrete Barrier (SSCB), (b) 32-inch tall F-shape concrete barrier to SSCB, and (c)TxDOT's 32-inch tall T221 vertical concrete wall to SSCB. The designs were required to meet AASHTO [Manual for Assessing Safety Hardware] MASH Test Level 3 (TL-3) criteria, and their compliance was to be evaluated using a combination of past testing results, impact simulation analyses, and limited full scale testing. Researchers developed designs and reinforcement details for all three transitions. The transition from SSTR to SSCB was comprised of a single slope barrier profile on the traffic side. This design did not require simulation or testing due to the known MASH compliance of the single slope barrier profile. Researchers developed designs of the other two transitions by performing dynamic vehicular impact simulations using MASH TL-3 impact conditions. Using results of these simulations, researchers selected the most critical cases for performance of full scale crash tests. The design selected for full scale testing was the transition between T221 and SSCB. MASH requires performing Test 3-20 (small car) and Test 3-21 (pickup) to evaluate transition designs. Both tests were performed on the transition between T221 and SSCB. The direction of vehicle impact in both tests was from the side of the SSCB to T221, which was selected based on simulation results. The transition performed acceptably in both tests for MASH TL-3 criteria. Based on the results of the simulations for F-shape to SSCB transition, and the fact that the more critical design of T221 to SSCB transition passed MASH testing, the F-shape to SSCB transition was also considered a MASH compliant design. This report provides details of the transition designs, simulation analyses,













Development of a Non-pinned Low-profile End Treatment


Book Description

In the early 1990s, the Low-Profile Portable Concrete Barrier (PCB) system, including both the sloped Low-Profile PCB segment and Low-Profile PCB end treatment, were developed. The original Low-Profile PCB end treatment was designed with steel pins inserted along the barrier centerline, through precast holes, and anchored to the pavement or subgrade. The purpose of these pins was to reduce lateral deflection of the end treatment during an impact. For various reasons, users of the Low-Profile PCB system have stated that the system would be more easily deployed if the vertical pins were not used in situations where lateral deflections can be permitted. The primary objective of the research presented herein was to determine the feasibility of removing the vertical, steel pins from the Low-Profile PCB end treatment in certain applications and if necessary make modifications. The secondary objective of the research presented herein was to demonstrate the applicability of the finite element analysis (FEA) to unpinned barrier systems. The research objectives were achieved through the use of sound engineering judgment, FEA, and a full-scale crash test. Based on sound engineering judgment and approximate strength analyses of the original Low-Profile PCB design, the author determined the system would most likely function acceptably but would have large lateral deflections. In order to increase connection rigidity and thus control lateral displacement, a plate washer was added to the barrier connection. The modified non-pinned Low-Profile PCB system was tested for strength in a full-scale crash test under Manual for Assessing Safety Hardware (MASH) test 2-35. Additionally, the recommended system was analyzed under similar test conditions with LS-DYNA, a finite element code. The recommended system passed the MASH test 2-35, in both a full-scale crash test and FEA. While this does not replace the original barrier, it does provide another option for use of the Low-Profile PCB in situations where sufficient room for deflection outside of the length of need exists. If this room does not exist, the barrier must remain pinned. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151825




Roadside Design Guide


Book Description







Transforming the Workforce for Children Birth Through Age 8


Book Description

Children are already learning at birth, and they develop and learn at a rapid pace in their early years. This provides a critical foundation for lifelong progress, and the adults who provide for the care and the education of young children bear a great responsibility for their health, development, and learning. Despite the fact that they share the same objective - to nurture young children and secure their future success - the various practitioners who contribute to the care and the education of children from birth through age 8 are not acknowledged as a workforce unified by the common knowledge and competencies needed to do their jobs well. Transforming the Workforce for Children Birth Through Age 8 explores the science of child development, particularly looking at implications for the professionals who work with children. This report examines the current capacities and practices of the workforce, the settings in which they work, the policies and infrastructure that set qualifications and provide professional learning, and the government agencies and other funders who support and oversee these systems. This book then makes recommendations to improve the quality of professional practice and the practice environment for care and education professionals. These detailed recommendations create a blueprint for action that builds on a unifying foundation of child development and early learning, shared knowledge and competencies for care and education professionals, and principles for effective professional learning. Young children thrive and learn best when they have secure, positive relationships with adults who are knowledgeable about how to support their development and learning and are responsive to their individual progress. Transforming the Workforce for Children Birth Through Age 8 offers guidance on system changes to improve the quality of professional practice, specific actions to improve professional learning systems and workforce development, and research to continue to build the knowledge base in ways that will directly advance and inform future actions. The recommendations of this book provide an opportunity to improve the quality of the care and the education that children receive, and ultimately improve outcomes for children.