Work Zone Mobility and Safety Program

Applying the Principles of the Work Zone Rule to Design-Build Projects, Two Case Studies: Comparison of Project Delivery Methods

2. Comparison of Project Delivery Methods

For the past century, design-bid-build was the project delivery method of choice for the majority of transportation projects. Recently, other types of project delivery methods have come into use by departments of transportation and other facility owners around the country. Though not a new idea, design-build is gaining popularity among the public sector, as many see it as a means to a faster and cheaper project delivery method. This section highlights the design-bid-build and design-build project delivery methods, as well as a few others that are used more infrequently. The Work Zone Safety and Mobility Rule was primarily developed with design-bid-build projects in mind. The last part of this section explains how the differences between the design-bid-build and design-build methods may affect the application of the Rule.


Design-bid-build is the traditional method for delivering transportation projects. The owner (or a consultant for the owner) prepares the design and a PS&E package that includes both construction and transportation management plans. Contractors engage in a competitive low-bid process to follow the specifics of the owner supplied plans and specifications. The lowest responsive, and in most cases prequalified bidder, is rewarded the project once the owner has determined that sufficient funding exists. Under the design-bid-build delivery process, the owner assumes the risk, guaranteeing to the Contractor that the PS&Es are error-free.


With design-build contracting, prospective proposers receive an RFP which includes the preliminary design (technical requirements for designing and constructing the project), and explains the scoring process and selection criteria. Both the engineering and construction services are included in the RFP and will be performed by the winning team under one contract. Generally the bid process is based on best value (price, schedule, and proposal score), but some agencies use a version of low-bid design-build. In contrast to design-bid-build, design-build relies on a single point of responsibility contract and is used to minimize risks for the project owner and to reduce the delivery schedule by overlapping the design phase and construction phase of a project. One of the benefits of a design-build project is that it allows the design-builder to be innovative in their method of designing and constructing a facility because the project is not fixed to an already-developed PS&E package, and this innovation can lead to project efficiencies. Because the design-builder has a significant amount of flexibility, the owner faces a different type of risk. There is reduced control over what the final product will look like and how it will be built because what is not specified in the RFP has variability.

Other Approaches

In addition to design-bid-build and design-build, there are several other delivery methods that are used for transportation projects. These include:

  • Construction Management/ General Contractor (CM/GC) - What sets this type of project delivery method apart is that instead of the Contractor taking on all the risk, each member of the team - the public agency, the designer, and the general contractor - has defined contractual obligations. This delivery method uses a qualification-based RFP process.
  • Public Private Partnership (PPP) - Overall, a PPP is a project in which there is an agreement formed between a public agency and a private firm that allows the private sector to assume more risk and responsibility in the financing and delivery of a transportation project. With this type of project, the public agency gets a new or upgraded facility that it might otherwise not have the funding to build at present. The private firm is an investing partner and in exchange for its investment in building a new or upgraded facility it gains a business opportunity and long-term revenue sources.
  • Build/Operate/Transfer - This is a type of PPP where construction and the initial operation of a facility are privately done for the term of the contract, prior to turning ownership over to the public agency at a set time in the future (e.g., 50 years).

These other delivery methods were not part of this case study.

How Differences between Design-Bid-Build and Design-Build May Affect Rule Application

Two of the major differences between the design-bid-build and design-build project delivery methods are who assumes the risk during the project and how the roles and responsibilities are handled. Because of these factors, the key aspects of the Rule may need to be applied to a design-bid-build project differently than they do a design-build project. Table 2-1 illustrates the different roles and responsibilities for the Owner/Agency and the Contractor in both project delivery methods. For a design-bid-build project, the Contractor is the construction firm building the facility and any subcontractors assisting, such as traffic control providers. For a design-build, the Contractor is the entire design-build team (designers, construction firms, subcontractors, consultants).

Another major difference between the design-bid-build and design-build project delivery methods is how the owner's requirements are presented to the Contractor or design builder. In a design-bid-build project, the construction documents (i.e., PS&Es) specifically identify what the Contractor is supposed to build, where they should build it, what they should build it with, and what phasing, staging, and traffic control are to be used while constructing the project. In a design-build project, the owner identifies the project requirements and specifications in the RFP, and allows the design-builder to choose the methods to create the construction plans and build the project. This allows the Contractor much greater flexibility to use its own innovations and efficiencies in building the job. For design-build projects, owners must make sure that they produce an RFP that is very strong on non-negotiable items, milestones, and safety, quality, and mobility elements, but leaves enough room for the proposer to create a solid proposal with value added elements and innovative ideas.

Table 2-1. Comparison of Roles and Responsibilities in Project Delivery Methods
Design-Bid-Build Method Design-Build Method
  • Develop plans and specifications
  • Identify and estimate work zone impacts
  • Identify appropriate transportation management strategies:
    • Temporary traffic control
    • Traffic operations
    • Public information
  • Identify coordination issues (e.g., utilities, enforcement, emergency response, community) and conduct upfront coordination
  • Develop TMP, including Traffic Control Plan (TCP)
  • Include in the PS&E those TMP items that will be implemented by the Contractor
  • Develop and implement public information/response plan
  • Implement TMP, except those components included in the contract
  • Perform quality assurance, control, and verification, including for maintenance of traffic
  • Monitor and manage work zone impacts during construction - has greater ownership than does the Contractor

  • Construct the project in accordance with the Owner/Agency plans and specifications
  • Implement the components of the TMP that were included in the contract
  • Coordinate with utilities on field work
  • Provide a safe worksite
  • Monitor and manage work zone impacts during construction, if included in the contract
  • Define requirements for work zone impacts assessment and allowable impacts during construction
  • Define requirements for transportation management strategies:
    • Temporary traffic control
    • Traffic operations
    • Public information
  • Identify coordination issues (e.g., utilities, enforcement, emergency response, community)
  • Develop RFP that outlines project requirements
  • Assist with public outreach and interagency coordination
  • Perform quality verification, including for maintenance of traffic
  • Provide oversight over monitoring and management of work zone impacts during construction

  • Design plans
  • Assess work zone impacts per contract requirements
  • Develop the TMP (including the TCP)
  • Construct the project based on the Contractor completed design and TMP
  • Implement TMP
  • Develop and implement public information plan - may share responsibility for public outreach with the Owner/Agency
  • Coordinate with utilities both upfront and during field work
  • Provide a safe worksite
  • Monitor and manage work zone impacts during construction
  • Perform quality control and quality assurance, including for maintenance of traffic

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