Design-build bridging documents for complex projects (part one)

December 7, 2015

Robert Connors, PE, CCS
Design-build (D-B) is increasingly used as a construction delivery method for complex projects to accelerate completion, contain liability for cost overruns, and shift operational risks. The work is finished earlier because construction advances as design is completed. Budget and scope creep are contained because bids are established earlier, prior to final design. Operational risks are shifted to the design-builder because design and construction advance collaboratively under a single contract. Potential D-B disadvantages for owners include less control, increased need for earlier and timely owner decisions, and resistance from those unfamiliar with the delivery method.

Properly prepared bridging documents advance owner goals to:

Bridging documents convey design and construction requirements to D-B teams bidding the project. Requirements are conveyed through a summary of work, technical requirements, plans, project constraints, reference materials, and contractual requirements. As this three-part series of articles will show, empirical evidence suggests key aspects to consider when preparing bridging documents include project definition, risk allocation, defining the procurement process, and following best practices.

Project definition
To ensure they get what they bought, public agencies typically require more project definition than private owners in bridging documents. Private owners have greater influence when refining the project definition in the final design, because future work will likely be awarded on past performance and personal relationships. Public agencies, on the other hand, have less leverage with D-B contractors due to public bidding laws. Public agencies also have internal customers such as construction, engineering, and maintenance departments that often prefer a higher level of definition and control.

The project definition:

Conveying required elements
Defining scope and technical requirements, the project agreement is the sole document defining contractual requirements. Design elements ‘required’ by the owner must be identified as such.

The bridging documents often include a technical design concept that presents the project scheme and layout. The technical design concept articulates ‘one way’ of designing the project, but not ‘the only way.’ It provides proof of feasibility within the project constraints. The technical design concept represents a five to 30 percent effort level, but varies by discipline and project. It can be used to estimate construction costs. The technical design concept is issued by bidders as a ‘no-reliance’ document, but it should not contain errors or be misleading.

The technical design concept, or portions of which are defined as ‘required’ in the project agreement, is used to define scope requirements and measure compliance.

Performance criteria
To maximize innovation opportunities, bridging documents employ performance criteria, which are measurable performance attributes of products defining their suitability for installation on a specific project. The more the project description is expressed in performance criteria, the more flexibility the design-builder has in creating an efficient final design.

As an example of performance criteria, the Ottawa Light-rail Transit (OLRT) is a complete new system including tunnels, railway, stations, maintenance facilities, vehicles, and a 30-year maintenance term. The bridging documents for this Canadian project established light-rail system performance criteria of 24,000 people her hour (pph). This allowed the proposing D-B teams to find the most efficient combination of vehicle capacity, headway, and station capacity to meet the performance criteria.

Innovation in design-build projects is encouraged when performance criteria is used. Collaboration between the designer and builder also results in innovation. As long as the bridging documents clearly define the project requirements and performance criteria and tests, the owner gains value.

A look at Longfellow Bridge, which crosses the Charles River to connect Boston's Beacon Hill neighborhood with the Kendall Square area of Cambridge, Massachusetts. Photo Ⓒ[2]
A look at Longfellow Bridge, which crosses the Charles River to connect Boston’s Beacon Hill neighborhood with the Kendall Square area of Cambridge, Massachusetts. Photo Ⓒ

Project cost is the critical owner and proposer concern. Bridging documents are used by the owner to develop a construction cost estimate. An accurate bridging cost estimate is essential for the owner’s budgeting, risk analysis, value analysis, and financial models. Bridging documents are used by proposers to develop their cost/bids. The overall level of design in bridging documents, and the level of design in specific project elements, is driven by what information is necessary to get an accurate bid and cost estimate.

Bridging documents provide proof of feasibility within the project constraints. On longer, more complex projects, and those with long lead items and schedule constraints, it is important to develop an accurate schedule with the bridging documents. The design-build approach results in accelerated project completion—the bridging documents must capture this value for the owner through setting accelerated—but still feasible—milestone and completion dates for the project in the bridging documents.

The bridging documents should disclose all relevant information to teams bidding on the project. Design-build transfers a lot of the risk from the owner to the D-B team, but it does not eliminate claims. Providing all relevant information reduces claims and results in better bids.

Quality control in the D-B project
Quality control (QC) is the sole responsibility of the design-build team. The owner may perform quality assurance (QA) testing or hire an independent QA consultant for acceptance. The bridging documents identify the overall quality planning, controlling, reporting, and auditing requirements. The D-B team is required to prepare a quality plan consistent with these requirements, often prior to selection.

The quality plan must include both construction and design QC components aligned with the owner’s standard requirements. The owner should trust the design-build team’s quality control system, but needs to be smart by requiring independent verification and auditing.

Along with project D-B quality requirements, bridging documents should identify applicable quality requirements of funding agencies, such as:

In the next installment of this three-part series on D-B bridging documents, this author explores issues related to risk allocation and the procurement process. The final article examines a range of best practices.

Robert Connors, PE, CCS, has more than 25 years of experience in engineering and management. He has a varied project portfolio that includes buildings, bridges, rail, wind turbines, and maintenance facilities. Connors specializes in procurement documents, project management, construction cost estimating, cost accounting, scheduling, claims analysis, finance, and contract administration. A certified construction specifier, he is also past treasurer of the Design-Build Institute of America’s (DBIA’s) New England Region. He can be reached at[6].

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  3. IT-90-5001-02.1:
  4. 23 CFR 637:
  5. Northeast Transportation Training and Certification Program:

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