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NCHRP 12-98 [Pending]

Recommended Guidelines for Prefabricated Bridge Elements and Systems Tolerances and Dynamic Effects of Bridge Moves

  Project Data
Funds: $300,000
Contract Time: 27 months
Staff Responsibility: Waseem Dekelbab

BACKGROUND
Many state DOTs and the Federal Highway Administration (FHWA) are actively promoting accelerated bridge construction (ABC) to reduce traffic impacts, onsite construction time, environmental impacts, and life-cycle costs and to improve work-zone safety, site constructability, material quality, and product durability while replacing the nation’s transportation infrastructure. The use of prefabricated bridge elements and systems (PBES) for ABC is growing fast. However, different challenges have been encountered during bridge construction related to proper fit-up of adjacent PBES and construction erection tolerances. Also, moving an entire superstructure or a bridge using slide-in operations or self-propelled modular transporters (SPMTs) for ABC imposes other challenges that depend on a bridge location and staging area for offsite construction of the bridge. Bridge moves impose dynamic forces on the bridge and supporting framing. These dynamic forces and their effects on bridge systems are not addressed in current design and construction guides. To help bridge owners, fabricators, and contractors to successfully use PBES and bridge moves for ABC, these challenges need to be addressed immediately.

OBJECTIVES
The objectives of this research are to develop (1) AASHTO bridge guidelines for (a) fabrication and erection tolerances for PBES and (b) tolerance acceptance criteria during bridge design, fabrication, and erection; and (2) AASHTO bridge guidelines to identify the dynamic forces resulting from bridge moves using slide-in operations and SPMTs and assess the effects of these forces on bridge systems.
Accomplishment of the project objectives will require at least the following tasks.

PHASE I—Planning
(1). Conduct a literature review of relevant domestic and international guidelines and manuals. The review should include research conducted through the NCHRP; Strategic Highway Research Program 2 (SHRP2); FHWA; and other national, state, and pooled-fund sponsored research. The review should cover research findings and owner and industry experiences. (2). Synthesize the literature review to identify the critical factors that need to be evaluated. Identify insufficiencies in existing guidelines and manuals for PBES and propose approaches to address them. (3). Propose a methodology, to be developed in Phase II, to develop tolerances and tolerance acceptance criteria guidelines. As a minimum, the guidelines shall address the following: vertical, horizontal, and plumb; substructure and superstructure; individual element and cumulative tolerances; connections; and deck grade. (4). Propose a methodology, to be developed in Phase II, to identify the dynamic forces resulting from bridge moves using slide-in operations and SPMTs and assess the effects of these forces on bridge systems. (5). Prepare detailed outlines of both recommended guidelines to be developed in Phase III. (6). Prepare Interim Report No. 1 that documents Tasks 1 through 5 and provides an updated work plan for the remainder of the project no later than 5 months after contract award. The updated plan must describe the process and rationale for the work proposed for Phases II through IV.
 
PHASE II—Methodology Development
(7). Based on the approved work plan, develop the proposed methodology for tolerances and tolerance acceptance criteria. Update the outline for the recommended PBES tolerances guidelines and provide a fully developed section of the guidelines to be selected by NCHRP. This section should be publication ready (i.e., AASHTO-style specification format) with appropriate level of detail. (8). Based on the approved work plan, develop the proposed methodology for dynamic forces and effects of bridge moves on bridge systems. Update the outline for the recommended guidelines for dynamic forces and effects of bridge moves on bridge systems and provide a fully developed section of the guidelines to be selected by NCHRP. This section should be publication ready (i.e., AASHTO-style specification format) with appropriate level of detail. (9). Prepare Interim Report No. 2 that documents Tasks 7 and 8 and also includes an updated work plan on Phases III and IV no later than 12 months after Phase I approval.

PHASE III—Guidelines Development
(10). Based on the approved work plan, develop both guidelines in AASHTO format including commentary. (11). Submit Interim Report No. 3 that documents Task 10 no later than 3 months after Phase II approval.

PHASE IV—Deliverables
(12). Revise the guidelines and commentary after consideration of the panel’s review comments. (13). Prepare final deliverables including (1) a final report that documents the entire research effort, (2) both guidelines as standalone documents, and (3) a recommended implementation plan for both guidelines.
 

STATUS: A research contractor has been selected for this project. The contracting process is underway.

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