Precast reinforced concrete box sections are proving to be a versatile means for the development of infrastructure. The use of segmental box sections is now covered in an ASTM standard, ASTM C1786, Specification for Segmental Precast Reinforced Concrete Box Sections for Culverts, Storm Drains and Sewers Designed According to AASHTO LRFD.

The American Association of State Highway and Transportation Officials document referenced in the title of ASTM C1786 employs load and resistance factor design methodology using factors developed from current statistical knowledge of loads and structural design.

Made up of separate segments that are assembled in the field to make the final structure, segmental box sections are being used in the building of culverts for the underground conveyance of storm water, industrial wastes and sewage. In addition, culverts can also function as pedestrian tunnels as well as wildlife passage areas under heavily travelled highways.

ASTM C1786 is the first ASTM standard specifically covering precast segmental box culverts. Prior to the development of C1786, producers and engineers would have to refer to ASTM standards for similar structures that did not address specifics regarding the design and manufacture of segmental culverts.

ASTM member Josh Beakley notes that, while the AASHTO LRFD Bridge Design Specifications provide design guidance, small communities and agencies are not always as familiar with the AASHTO requirements as are the state departments of transportation that use them on a more regular basis.

“C1786 incorporates design guidance as referenced in the AASHTO LRFD Bridge Design Specifications, with the production and quality control measures synonymous with an ASTM precast standard, so that practicing engineers can get a good start when considering the use of this product,” says Beakley.

C1786 was developed by Subcommittee C13.07 on Acceptance Specifications and Precast Concrete Box Sections, which is under the jurisdiction of Committee C13 on Concrete Pipe.

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