BACKGROUND

Culvert and storm drain systems constitute critical nodes in U.S. transportation networks; however, many of these structures have met or exceeded their design service life. Replacing culverts under difficult constraints (i.e., high fills, high-volume roadways, difficult maintenance of traffic conditions) presents unique challenges causing transportation agencies to explore rehabilitation options. Much of the maintenance and restoration performed on buried structures is based on past practices and procedures in which state departments of transportation (DOTs) are familiar and experienced with implementing. 

Many times, standardized guidance for the rehabilitation design process is local. Meanwhile, new rehabilitation technologies continue to emerge without sufficient information on when and how they should be applied. The recent American Association of State Highway and Transportation Officials (AASHTO) Culvert and Storm Drain System Inspection Guide (CSDSIG) published in 2020 provides a roadmap for the inventory and inspection of culverts and storm drains. The next logical step is to determine a course of action for assets identified as deficient.  Research is needed to develop strategies for state DOTs on when to replace versus rehabilitate and the choice of a rehabilitation method.

OBJECTIVE

The objective of this project is to develop a guide for state DOTs for evaluating when to either replace or rehabilitate culverts and storm drains. The guide will also assist designers in the selection of the most appropriate rehabilitation method(s) along with the applicable loading conditions and design method to use when applying the chosen method. 

Accomplishment of the project objective will require at least the following tasks.

TASKS

Task descriptions are intended to provide a framework for conducting the research. The NCHRP is seeking the insights of proposers on how best to achieve the research objective. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and subaward time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objective.

Note: Proposers shall include the schedule for each phase in their research plans. The sequencing of tasks and deliverables (such as technical memorandums or summary reports) shall be structured for delivery in quarterly progress report submissions. An in-person interim meeting, to be held in Washington, DC, should follow the submission of the first interim report.

PHASE I—Planning

Task 1. Conduct a literature review of research, documents, and case studies on culvert rehabilitation methods relevant to this research. The review shall include published and unpublished documentation and research conducted by the NCHRP; Federal Highway Administration; other national, state, and local agencies; and international organizations.

Task 2. Synthesize the results of the literature review to identify knowledge gaps related to the research objective. These gaps should be addressed in the final product or the recommended future research, as budget permits.

Task 3. Propose the research plan to be executed in Phase II to achieve the research objective. At a minimum, the research plan shall include:

• Reviewing current culvert and storm drain rehabilitation strategies. Include discussion of their appropriate use and limitations as demonstrated by case studies.
• A plan for stakeholders’ engagement. Include interviews with industry and practitioners.
• Identifying critical factors to consider when determining whether to replace or rehabilitate culverts and storm drains, and how to choose a proper rehabilitation method to augment the AASHTO CSDSIG. Include all the necessary condition information to be collected as input into the decision on rehabilitation or replacement and as input to complete the rehabilitation designs.
• Developing recommendations for design parameters and limitations, based on the AASHTO LRFD methodology, for each rehabilitation method.
• Developing acceptance criteria for construction completion.
• Developing draft language for consideration by AASHTO to incorporate the research results in a future AASHTO guide (herein called the AASHTO Deliverable).
• Developing design examples to demonstrate the application of the design for each rehabilitation method. The design examples will be prepared in Phase II.

Task 4. Provide an annotated outline of the proposed AASHTO Deliverable including examples to demonstrate the application of the proposed deliverable.

Task 5. Prepare Interim Report No. 1 that documents Tasks 1 through 4 and provides an updated work plan for the remainder of the research. The updated plan must describe the process and rationale for the work proposed for Phases II and III.

Note: Following a 1-month review of Interim Report No. 1 by the NCHRP, the research team will meet with the project panel to discuss the interim report. Work on Phase II of the project will not begin until authorized by the NCHRP.

PHASE II—Execution

Task 6. Execute the research plan according to the approved Interim Report No. 1 and update the annotated outline of the AASHTO Deliverable after consideration of the panel’s review comments.

Task 7. Develop a complete sample section of the AASHTO Deliverable to be selected by the NCHRP. This section should be publication-ready with an appropriate level of detail. The format shall meet the current AASHTO formatting guidelines and it shall include commentary.

Task 8. Develop the remaining sections of the AASHTO Deliverable and the design examples.

Task 9. Prepare Interim Report No. 2 that documents Tasks 6 through 8 and provides an updated work plan for the remainder of the research. The updated work plan must describe the process and rationale for the work proposed for Phase III.

Note: Following a 1-month review of Interim Report No. 2 by the NCHRP, the research team will meet with the project panel to discuss the interim report. Work on Phase III of the project will not begin until authorized by the NCHRP.

PHASE III—Final Products

Task 10. Revise the AASHTO Deliverable and the design examples developed in Phase II after consideration of the panel’s review comments.

Task 11. Submit the final deliverables including (1) the AASHTO Deliverable, (2) a conduct of research report that documents the entire research effort and findings, (3) design examples, and (4) a stand-alone technical memorandum titled “Implementation of Research Findings and Products.” See Note IV for additional information.

Note: Following receipt of the draft final deliverables, the remaining 3 months shall be for NCHRP review and comment and for research agency preparation of the final deliverables. The budget for Phase III shall be $45,000.

SPECIAL NOTES

A. The research team should anticipate making two presentations to appropriate technical committees at AASHTO meetings.

< < < IMPORTANT > > >

I.     The brochure Information and Instructions for Preparing Proposals for the Transportation Research Board’s Cooperative Research Programs includes extensive guidance on the preparation of proposals for submission to CRP. Revisions to these instructions are highlighted in yellow within that document.

II.    Proposals will be rejected if any of the proposed research team members work for organizations represented on the project panel. The panel roster for this project can be found at https://www.mytrb.org/OnlineDirectory/Committee/Details/7258. Proposers may not contact panel members directly; this roster is provided solely for the purpose of avoiding potential conflicts of interest.

III.  The text of the final deliverable is expected to be publication ready when it is submitted. It is strongly recommended that the research team include the expertise of a technical editor as early in the project timeline as possible. See Appendix F of the Procedural Manual for Subawardees Conducting Research in the Transportation Research Board’s Cooperative Research Programs for technical editing standards expected in final deliverables.

IV.  The required technical memorandum (no more than 10 pages) titled “Implementation of Research Findings and Products” should address the following implementation frameworks: (1) Effective Products; (2) Implementation Stages; (3) Implementation Drivers; (4) Implementation Teams; and (5) Product Feedback. For more information on the frameworks, read the TR News article “Active Implementation at the National Cooperative Highway Research Program: Frameworks for Moving Research into Practice,” available at https://www.nationalacademies.org/osdocs/NCHRP20-44_ActiveImplementation-TRNews.pdf.

V.   The National Academies have an ethical and legal obligation to provide proper attribution whenever material from other sources is included in their reports, online postings, and other publications and products. TRB will review all Cooperative Research Programs draft final deliverables using the software iThenticate for potential plagiarism. If plagiarized text appears in the draft final deliverable, the research team will be required to make revisions and the opportunity to submit future proposals may be affected.