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Aerial photo provides a view of the original Interstate 5 Willamette River Bridge and temporary detour bridge in Eugene-Springfield, Ore.

A construction project’s success can be measured by how its delivery method controls scope, costs, schedule, and quality. The Oregon Department of Transportation (ODOT) is using alternative contracting methods to accelerate delivery while controlling costs on the Oregon Transportation Investment Act III State Bridge Delivery Program, a $1.3 billion program to repair and replace hundreds of bridges throughout the state. The agency chose construction manager/general contractor (CM/GC) to deliver the largest bridge replacement project in the program, the Interstate 5 Willamette River Bridge project.

ODOT constructed the original bridge nearly 50 years ago. During an inspection in 2002, engineers identified shear cracks severe enough to require the agency to place weight limits on the bridge, and heavy-haul trucks had to be routed on a 200-mile detour. The agency erected a temporary detour bridge over the Willamette River to keep freight and other vehicles moving while it began the $204 million replacement project.

The bridge project is one of the most complex in the program: It is located between two cities with highly engaged citizens; it crosses a set of railroad tracks, a four-lane boulevard, and a river; and it is flanked by two parks with significant environmental constraints. Once completed, the bridge will be approximately 1,759 feet long.

Because of the project’s size and complexity, ODOT set its sights on a new, versatile delivery method. Instead of using traditional contracting methods – design-bid-build or design-build – ODOT, for the first time, chose CM/GC (similar to construction manager at-risk). While this contracting approach is well established in vertical construction, it is still relatively uncommon in highway and bridge construction.

Procurement through CM/GC
Selecting the strongest possible team is even more important with CM/GC because the design firm and contractor work together with ODOT for the length of the project. Whereas in design-bid-build the contract is awarded to the lowest price bidder, other values influence the selection of the prime contractor. When ODOT evaluated candidates for this project, the primary scoring categories considered were the expertise of the organization and its key personnel; demonstrated understanding of roles, responsibilities, and goals in CM/GC project delivery; and approach. ODOT also included as a scored category the proposed fee percentage as compared with that of other candidates.

Expertise of the owner, architecture and engineering (A/E) firm, and contractor is important in the CM/GC partnership, but also crucial to project success is their ability to collaborate. If any single party isn’t a good partner, the process suffers. ODOT’s prime contractor, Hamilton Construction Co., and its A/E firm, OBEC Consulting Engineers, have proven to be outstanding partners.

In CM/GC project delivery, the prime contractor is involved throughout the entire process, collaborating with the A/E firm and the owner as the project evolves. Throughout the design phase, Hamilton provided expertise on constructability and cost estimating. The design played to Hamilton’s strengths as a construction firm, making the bridge easier to build and ultimately giving the agency greater value for its investment.

ODOT celebrated the halfway point of the project in August 2011, and the CM/GC contracting method has already proven its value in several ways.

Collaboration leads to successful outcomes
While designing the type, size, and location of the new bridge, ODOT had a dynamic public involvement process. For local residents, it was important that the new bridge enhance the area’s natural beauty. Working with citizens, community stakeholders, public agencies, artists, and architects, the agency integrated the community’s input into the design. Having the owner, A/E, and contractor on the decision-making team enabled the project to adapt quickly and efficiently to public input.

Crews prepare to jack the arch ribs apart during construction of the new Interstate 5 Willamette River Bridge.

The CM/GC method allowed OBEC to respond to design input from the community with conceptual designs, which Hamilton could quickly and accurately evaluate for cost, schedule, and feasibility while ODOT provided the authority to approve agreed-upon changes.

The collaborative effort led to the project’s defining feature: its graceful deck-arch design. These structures – side-by-side northbound and southbound spans 16 feet apart – are a landmark for the community and complement the scenic setting of the bridges.

As design progressed, CM/GC also helped ODOT manage risk, resulting in controlled costs. In design-build delivery, the owner mitigates, accepts, or passes risk on to the contractor. If the owner decides to pass the risk on, the contractor has to price it into the bid. For this project, the team eliminated a lot of Hamilton risk from the Hamilton price; the agency held the price of risk as a contingency, which lowered the cost. If the risk materializes, ODOT will expend the funds; if not, the agency will keep them.

CM/GC methodology also reduces the number of change orders, in large part because the contractor is involved in the project design. The conditions associated with construction work are clear to the contractor, risk has been identified and appropriately assigned, and the design is tailored to the contractor’s capabilities.

When constructing the arches on the southbound structure, Hamilton ran into an enormous change and took it in stride. True arches theoretically experience only compression, no bending forces. The arches on this project are not true arches – their profile is too flat. To minimize bending forces and induce compression into the arches, the design calls for the arch halves to be jacked apart at the peak. The jacking forces and distance were calculated; however, when executed on the southbound bridge arch spans, the distance was different from what the team anticipated. It caused changes to the spandrel columns that support the deck. Normally, with design-bid-build, the contractor would consider that a change and expect compensation. Anticipating the possibility, Hamilton was able to adapt without needing to request a change in compensation or time, which allowed the project to stay on time and on budget.

In addition to learning from its successes, ODOT has already taken stock of factors that will make its next CM/GC project even more effective. Lessons learned for future projects include the following:

Switching drivers mid-project is difficult and counterproductive. Success depends on the owner’s active participation and leadership. The project team is best served by a highly skilled owner’s manager involved from the beginning of procurement until the completion of construction.

Select for a strong team orientation. For optimal success, each of the three contractual entities – owner, A/E firm, and contractor – must possess a strong team orientation and an attitude that places project success ahead of individual company advantage. The owner needs to make teamwork a prominent part of the selection scoring and interview the potential partners carefully.

Resolve project challenges. Finally, CM/GC is well suited for projects where owner and contractor input is essential to design development as well as to managing risks along the way. Its flexibility allows owners to cost-effectively resolve project challenges.

At ODOT, we are pleased with the flexibility, innovation, and oversight that CM/GC allowed us on a large, complex, and highly public project.

The southbound structure opened to traffic ahead of schedule in August 2011.

Tim Dodson has 23 years of project management experience with the Oregon Department of Transportation. Currently, he oversees the work of consultants for the delivery of full-service outsourced projects.