The National Academies

NCHRP 12-89 [Final]

Recommended AASHTO LRFD Tunnel Design and Construction Specifications

  Project Data
Funds: $700,000
Research Agency: PB Americas, Inc.
Principal Investigator: John Wisniewski
Effective Date: 6/21/2011
Completion Date: 7/31/2016

The AASHTO LRFD Bridge Design Specifications, Section 12—Buried Structures and Tunnel Liners provides little information on the design and construction of highway tunnels. Although AASHTO adopted the FHWA Technical Manual for Design and Construction of Road Tunnels–Civil Elements, design and construction specifications for tunnels are needed considering existing manuals and specifications, especially those developed by FHWA and the National Fire Prevention Association (NFPA).  
The objective of this research was to develop stand-alone recommended design and construction specifications for highway tunnel systems. In developing these specifications, consideration were given to safety and operations, maintenance, and inspection of tunnel systems. The research produced design and construction specifications with commentary in the format of the AASHTO LRFD Bridge Design Specifications.
The agency’s final report documents and presents the methodology used to develop recommended Load and Resistance Factor (LRFD) based tunnel design specifications. A literature search was performed to review existing design codes and standards, project specific design criteria, reports, and technical publications. Limited calibration of the load factors was performed based on results from the analysis of a circular bored tunnel. A summary of the calibration procedure is presented in thereport. Future research to expand the specifications is provided. The design specifications are not included in the report.
STATUS:  AASHTO Subcommittee on Bridges and Structures has adopted the proposed LRFD Tunnel Design and Construction Specifications on June 29, 2016. The specifications published by AASHTO: https://bookstore.transportation.org/item_details.aspx?ID=3742.

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