CHAPTER 2

Literature Review

This chapter summarizes the findings from the literature review on the techniques and strategies used by DOTs for complex bridge replacement scenarios. Relevant documents were searched using the Transportation Research Board’s TRID database and supplemented with internet searches. The literature review indicated that while there are DOT resources on bridge replacement guidelines and national or DOT documents on construction techniques, procurement, and project delivery that relate to bridge replacements in general, there is a lack of specific documentation on methods and strategies used for complex bridge scenarios and associated decision-making by the DOTs. The survey responses and case example interviews identified that DOTs tend to have custom processes for decision-making regarding complex bridge replacement scenarios, which focus on the unique complexities, challenges, and constraints of each project. While DOTs have guidance documents related to the selection, development, programming, and funding of bridge replacement projects; bridge design manuals that may include certain aspects of decision-making; and guidance documents on ACMs and PDM that are utilized as techniques to help with bridge replacement scenarios, there were not specific resources on the methods and strategies used by DOTs specifically for complex bridge replacement scenarios. However, when the DOTs were asked in the survey whether they have written policies, rubrics, guidelines, metrics, or tools for bridge replacement decision-making in complex scenarios, responder DOTs provided guidance documents on bridge design, construction, project development, APD (e.g., ABC), and ACM (e.g., D-B) or DOT bridge manuals as the guidance documents most relevant to the synthesis scope. These DOT guidance documents, along with related documents from FHWA, are presented in Table 2-1. Since DOT guidance documents are updated as needed, searching for the latest version of these documents is recommended for future reference.

FHWA has a definition for unusual structures, which can be classified as a subset of complex bridge replacement scenarios. (FHWA 1998). FHWA offers guidance on project oversight for unusual structures through a memorandum (FHWA 1998), which outlines the responsibilities of FHWA Headquarters and field offices regarding reviewing and approving preliminary plans for unusual bridges and structures. For this guidance, unusual bridges are defined as “those the Divisions determine have: (1) difficult or unique foundation problems, (2) new or complex designs with unique operational or design features, (3) bridges with exceptionally long spans, or (4) bridges being designed with procedures that depart from currently recognized acceptable practices. Other examples are noted as bridge types that deviate from AASHTO bridge design standards or AASHTO guide specifications for highway bridges; major bridges using load and resistance factor design specifications; bridges requiring abnormal dynamic analysis for seismic design; bridges using a three-dimensional computer analysis; bridges with spans exceeding 152 m (500 feet).” FHWA emphasizes the importance of timely submittals for approval or assistance, noting that early involvement is particularly beneficial in D-B contracts, as decisions on structure types and sizes significantly affect the contract bidding process.

Table 2-1. Resources relevant to the synthesis scope.

^* Provided by the DOT as a survey response

An example of an unusual bridge is Miami’s Fountain Signature Bridge, which is currently under construction with an estimated completion date of late 2027. The bridge is the centerpiece of the I-395/SR 836/I-95 D-B project, which consists of replacing existing bridges, adding new ones, and widening existing ones. This D-B project is a partnership between the Florida Department of Transportation (FDOT) and the Greater Miami Expressway Agency (GMX) (Florida DOT 2024). The signature bridge is one of the bridge replacements. With its complex design outside normal AASHTO design specifications, this bridge meets all four FHWA criteria for unusual bridges. The Fountain arches will be constructed using precast concrete segments. Once finished, the bridge will be the largest concrete segmental arch bridge in the United States and the second-largest concrete arch bridge overall (Archer Western-de Moya Joint Venture 2017). SR 836 (also called the Dolphin Expressway), I-95, and I-395 converge at an interchange that manages over 450,000 vehicle trips daily (Florida DOT 2024). This interchange provides access to communities within Miami and Miami Beach, as well as to ports and major tourist destinations (Florida DOT 2024). The Florida DOT and the City of Miami are collaborating to enhance the design of the community spaces beneath I-395 and specified design requirements for I-395 bridges to be constructed at higher elevations and with fewer support columns for the design of these community spaces (Florida DOT 2024). The project website includes construction updates and minutes of monthly stakeholder meetings, which aim to inform the community of all project milestones and to communicate the proposed improvements (Florida DOT 2024).

The FHWA guidance documents on construction techniques, procurement, and project delivery provide critical resources for DOTs. The FHWA guidance document on bridge bundling (D’Angelo et al. 2019) outlines a program to manage and improve the nation’s bridge infrastructure efficiently. Bridge bundling involves grouping multiple projects into a single contract for preservation, preventive maintenance, rehabilitation, or replacement. This approach leverages various funding options and partnerships to streamline project delivery and reduce costs. The document highlights that bridge bundling is already practiced by several DOTs, resulting in significant cost savings and expedited project timelines. It emphasizes the benefits of bundling for all types of bridge projects, from those in good condition needing preventive maintenance to those in poor condition requiring major rehabilitation or replacement.

The guidebook is a manual for DOTs, local public agencies, and other bridge owners that provides detailed instructions on implementing bridge bundling programs. It covers the entire process, from selecting bridges and determining goals to identifying funding sources and choosing the best PDMs. Additionally, it addresses critical considerations such as environmental reviews, right-of-way issues, and risk management. The document includes case studies, best practices, and links to additional resources to support practical bridge bundling. By following this guidance, agencies can save time and cost while improving the bridge infrastructure’s overall condition and reliability.

The Fast 14 Project is an example of a complex bridge replacement scenario in which bundling was utilized as one of the strategies (FHWA 2012), along with ABC. Led by MassDOT, the project used ABC to replace 14 aging bridges on I-93 in Medford, MA. This project, completed in just 10 weekends, aimed to minimize traffic disruption while ensuring the safety and quality of the new structures. The project utilized prefabricated modular bridge units to expedite construction. Work was confined to 55-hour windows over weekends to avoid weekday traffic disruption. For traffic management, MassDOT implemented a movable barrier system to maintain two-lane traffic in both directions during construction and developed detailed traffic management plans for each weekend to ensure smooth flow and minimize congestion. For project collaboration, a multidisciplinary team from MassDOT, FHWA, and local agencies held regular team meetings to ensure coordinated efforts and timely resolution of design and construction issues. Extensive communication efforts included stakeholder meetings, an interactive project website, email

alerts, and real-time traffic information through portable signs. The Fast 14 Project successfully replaced 14 bridges without significant incidents, maintaining regional traffic flow and minimizing inconvenience. This innovative approach demonstrated the feasibility of accelerated construction, with initial findings suggesting costs comparable to those of conventional methods while significantly reducing project duration and public impact (FHWA 2012).

The guidance documents from other DOTs shared by survey respondents are the most relevant to the synthesis scope and are potentially the most useful for DOTs. The six DOTs that provided case examples also shared guidance documents. The relevant content for techniques and strategies that they use for complex bridge replacement scenarios are cited in the case examples. Twelve DOTs provided guidance documents in response to their existing guidelines or policies regarding complex bridge replacements (Table 2-1). These documents can be categorized in three categories:

• Guidance documents on bridge design and project development (Colorado, Iowa, Louisiana, New York State, Texas, and Washington State)
• Guidance documents on ABC (California, Minnesota, Utah, Wisconsin, and Iowa)
• Guidance documents specifically on D-B PDM (South Carolina, Massachusetts, and Washington State).

Some DOTs shared documents in two of the categories. These shared documents indicate that the responder DOTs may utilize ABC and D-B strategies for complex bridge replacement scenarios. Also, DOTs do not necessarily have a unique process or strategy for complex bridge replacements but rather follow DOT guidelines for each project, typically found in bridge, bridge design, and project development documents. These observations align with the survey findings and the case examples.

Preliminary design chapters of DOT bridge design manuals detail information on the existing process or guidance for early decision-making for bridge replacement projects. For Iowa DOT, the Preliminary Bridge Design Unit is responsible for developing concepts and preliminary layouts for highway structures within the Bridges and Structures Bureau, including bridges, walls, culverts, and miscellaneous structures (Iowa DOT 2024). The Iowa DOT’s structure replacement process for all structures begins with a concept statement developed by the Preliminary Road Design Unit and supported by the Preliminary Bridge Design Unit [Chapter 3 – Preliminary Design of Bridges, (Iowa DOT 2024)]. The statement details the structure type, size, and estimated costs. Consultants may assist with road and bridge design, necessitating close coordination with Iowa DOT. The process is initiated with a “Bridge Proposal for Concept Statement” memo, which includes essential project information such as site details, traffic estimates, and bridge width. Key meetings include a pre-contract project scoping meeting to define the project scope and fee and a “kick-off” meeting to discuss project requirements such as geometric needs, hydrology, structure options, traffic management, and schedule. Hydrology and hydraulic analysis are critical, and the annual exceedance probability discharge (AEPD) spreadsheet and possibly statewide light detection and ranging (LiDAR) data are used for preliminary hydraulic modeling. Review of maintenance and inspection reports, along with coordination with the bridge bureau rating engineer, ensures comprehensive planning. Cost estimates are parametric and based on square footage or concrete volume. Deliverables include meeting summaries, structure selection statements, three-dimensional computer-aided digital design (3D CADD) models, hydrology and hydraulic design calculations, and cost estimates. A concept team review meeting finalizes the preferred replacement structure and documents project costs and decisions.

The Iowa DOT may utilize ABC techniques for complex bridge replacement scenarios and has a decision-making and design guidance policy for approaching a new bridge or bridge replacement with an ABC technique, such as lateral bridge slide or prefabricated bridge elements and

systems (Iowa DOT 2024, Chapter 8). The Iowa DOT evaluates projects for potential ABC using a multi-phased approach, except in emergencies (Figure 2-1). A concept team, comprising DOT staff from various bureaus, assesses the suitability of ABC bridge projects based on an ABC rating score.

1. Initial Assessment: The concept team uses the ABC rating score to rank bridge replacement candidates. This stage filters projects based on their suitability for ABC.
2. Optional Second Stage: A more rigorous evaluation using the ABC Analytic Hierarchy Process (AHP) decision-making software may be conducted for borderline or large projects to determine if ABC is appropriate.

The Project Delivery Division director and Bridges and Structures Bureau (BSB) advisory team, consisting of key bridge engineering personnel, must approve any ABC candidates. This team prioritizes candidates and assesses resources, considering funding and staffing. Approved projects will have both traditional and ABC options fully concepted as alternatives leading to a selection of a preferred alternative. The concept team evaluates contracting methods, structural placement techniques, and the use of prefabricated elements to ensure timely construction. The final concept letter, including the recommended ABC approach, is reviewed by various bureaus and the district. If concurred, the project-specific ABC approach is further developed in a Type, Size & Location (TS&L) Plan by the Preliminary Bridge Design Unit.

The preliminary design process at the Louisiana Department of Transportation and Development (LA DOTD) involves a Stage 0 study to determine the practical feasibility of potential projects, encompassing technical, environmental, and financial aspects (LA DOTD 2013). The project’s complexity dictates the necessary level of detail in the process. The process begins with developing a preliminary purpose and needs statement, which outlines the reason for proposing the project and the issues it aims to address. This includes collecting data such as descriptions of existing facilities, background information, air quality context, justification of need, multimodal considerations, roadway deficiency data, demographic data, transportation demand forecasts, and adjacent project identification.

Next in the LA DOTD process, a range of project alternatives is identified and described to address the purpose and need. These descriptions include essential design criteria, major design features, and any design exceptions. Technical analyses on safety, capacity, air quality, and other relevant factors are conducted to a level of detail compatible with Stage 1 requirements. The alternatives are reviewed for potential environmental impacts through an initial assessment of the natural and human environment. This process involves defining the context of the area and conducting preliminary checks for environmental impacts. The preliminary scope and cost estimate for each alternative is developed, including estimates for right-of-way, utility relocations, construction, environmental studies, mitigation, and design engineering. Lastly, anticipated funding sources are identified, and a value planning/value engineering assessment and constructability review are performed for major projects. The overall objective is to ensure a seamless transition from planning to the environmental process, reducing time and costs while delivering transportation improvements efficiently. The steps and aspects summarized from the LA DOTD preliminary design process exemplify the many aspects of decision-making for transportation projects like bridge replacements and illustrate the complexity that leads to a case-by-case assessment of these infrastructure projects.

The Minnesota DOT (MnDOT) may also utilize ABC for complex bridge replacement scenarios. MnDOT uses a three-stage ABC process to improve the efficiency of bridge construction projects (MnDOT 2013). Stage 1 uses a data-driven decision-making process to evaluate all state-owned bridges, excluding culverts. Bridges are scored, results are recorded in the structure inventory sheet and BRIM (Bridge Replacement and Improvement Tool), with bridges scoring

above 60 (top 37%) advancing to the next stage. Stage 2 involves subjective assessments led by the district project manager, with assistance from the traffic engineer, resident engineer, and regional bridge construction engineer. This team reviews specific questions to determine if ABC is appropriate and identifies draft alternatives. Stage 3 focuses on selecting the best ABC technique or methodology. This stage, conducted by the district in collaboration with the bridge pre-design team and the regional bridge construction engineer, involves developing and comparing contracting and ABC alternatives, analyzing advantages and disadvantages, and preparing cost estimates. The Oregon DOT AHP software (Doolen, Saeedi, and Emami 2011) may be used to aid in decision-making. The final selection of an alternative considers whether the benefits outweigh the costs and examines the possibility of using ACMs. This structured approach aims to make data-informed and strategically evaluated decisions to implement ABC methods. It should be noted that the Oregon DOT AHP is a product of a pooled-fund project led by the Oregon DOT with the California, Iowa, Minnesota, Montana, Texas, Utah, and Washington State DOTs as collaborators. The ABC Rating Procedure Spreadsheet and Decision Flow Chart shared by the Utah DOT is a custom version of the Oregon DOT AHP (Utah DOT 2014).

The New York State Department of Transportation (NYSDOT) employs an initial bridge project scoping process detailed in the NYSDOT Bridge Manual (NYSDOT 2021) for all bridge replacement projects, which is to be used in conjunction with the NYSDOT Project Development Manual (NYSDOT 2004a). This essential step in project development begins with “scoping,” based on teamwork, stakeholder involvement, informed decision-making, consensus-building, and thorough documentation. Key activities include forming an interdisciplinary team, engaging with the public and stakeholders early, and using informed decision-making to identify viable project alternatives and preliminary cost estimates. The culmination of this process is the scoping and design approval document (DAD), which serves as an engineering record documenting project needs, objectives, feasible alternatives, and environmental commitments. This document is critical for moving forward with the final contract documents. It must be approved early in the development process to ensure all considerations are addressed efficiently and effectively, reducing overall design time and improving project delivery. The project development process is summarized in a flowchart and provided on the NYSDOT website (NYSDOT 2004b).

South Carolina DOT Design-Build Procurement Manual, created in cooperation with the South Carolina Department of Transportation (SCDOT) and FHWA, offers guidelines for identifying, selecting, procuring, and awarding D-B projects (SCDOT 2017). It details the critical processes in the D-B procurement and delivery system, ensuring structured and standardized approaches for managing these projects efficiently and effectively.

The project development process for D-B projects at the SCDOT generally mirrors the initial stages of the traditional D-B-B process, which includes planning, concept development, and environmental considerations, as outlined in the project development process. However, for D-B projects, preliminary engineering typically concludes at the preliminary design phase, though the extent of design completed can vary depending on the specific project.

In SCDOT D-B projects, sufficient preliminary engineering is crucial to accurately determining preliminary roadway alignments, bridge layouts, and geotechnical or subsurface conditions. This foundational work is essential for developing the project scope, identifying right-of-way (ROW) limits, assessing potential environmental impacts, and understanding permitting requirements. These preliminary details are vital for defining the request for proposals (RFP) project requirements.

The preliminary engineering is conducted in enough detail to ensure the project can be executed within the set boundaries, schedule, and budget. However, advancing the preliminary engineering too far may restrict the innovative potential of design-build teams and introduce

additional risks to SCDOT. To manage these risks, the project manager collaborates with relevant SCDOT offices to identify risks, develop mitigation strategies, and finalize the RFP, thereby guiding the overall development of the D-B project.

The literature review has highlighted the varied processes adopted by different DOTs, noted available national guidance on certain strategies relevant to complex bridge replacement scenarios, and underscored a common need for tailored solutions to address unique project demands and constraints. There remains a gap in guidance on standardized processes adaptable across diverse scenarios. Each DOT incorporates distinct approaches, informed by existing frameworks and innovative practices like bridge bundling, ABC, ACMs, or alternative PDM, which underscore the benefits of streamlining project delivery and enhancing cost efficiency. Furthermore, the integration of public and stakeholder input, as well as the alignment of environmental, social, and economic considerations from the preliminary stages, are emphasized. These practices aim to ensure that the selected strategies are technically feasible, cost-effective, and socially and environmentally responsible. Therefore, there is value in fostering collaborative efforts across DOTs to share insights, develop adaptable tools, and create a more cohesive framework that accommodates the complexity of bridge replacement projects while promoting innovation and sustainability in infrastructure development.