A major knowledge gap in the world of Accelerated Bridge Construction (ABC) is prefabricated barriers. The knowledge gap is a combination of limited pre-existing prefabricated barriers and the new AASHTO Manual for Assessing Safety Hardware (MASH) crash testing requirements.
Precast concrete barriers were previously crash tested to NCHRP Report 350 requirements. Some of these barriers were evaluated for Test Level 3. States are moving to higher level designs. Test Level 4 is common. Some agencies are moving to Test Level 5. The MASH provides current crash-testing requirements.
The goal of this research is not to develop a “new barrier shape.” The concept is to identify and MASH crash-test prefabricated versions of existing NCHRP Report 350 approved barriers. During the preliminary phases of the project, a questionnaire can be sent to owner agencies to determine which barriers are commonly used and what test levels are being specified. From that knowledge, the project panel can select the three most appropriate barriers and test levels for the crash testing portion of the project.
Due to durability concerns with exposed concrete surfaces, the researchers and panel may consider the use of non-corrosive reinforcing bars in one of the specimens. The major challenges to address in this research include: (1) accommodating various geometric configurations such as vertical curves, horizontal curves, and variable cross slopes; (2) accommodating tolerances; (3) developing durable (waterproof) connections; and (4) accommodating accelerated construction schedules (operational in under 12 hours).
The objective of this research is to identify and MASH crash-test three non-proprietary prefabricated concrete barriers that can be used on ABC projects. The barriers need to be crash worthy, easy to install, practical, durable, and be able to accommodate variations in geometry.
Virtually every state DOT is using ABC at this time and has a need for MASH-tested prefabricated concrete barriers. This work will potentially be a value to all DOTs. Current ABC designs have had to resort to prefabricating barriers integral with prefabricated decks. There are currently no MASH-tested prefabricated concrete barriers on the market. Having several barrier designs that are crash tested and versatile will help fill a major gap in the ABC world.