In project delivery, balancing the three critical factors of time, money and quality is often a challenge. But two alternative methods of contracting helped speed construction, kept costs down and led to innovation on the bridge program.
Most of the roughly 80 bundles were contracted according to the standard design-bid-build method, in which ODOT or an engineering firm designs a bridge, and once design is complete, a contractor bids for and builds the project. But 11 of the bundles used a newer delivery method, design-build, in which an engineering firm and a construction company partner from the outset to bid on a project on which they collaborate continuously.
An advantage of design-build is that construction can begin before the design is finished, so work moves ahead more quickly. Traditionally, design-build has been used on projects with budgets greater than $100 million, but on the bridge program ODOT used this procurement method successfully for 11 projects in the $20 million to $60 million range, to encourage smaller Oregon businesses to bid. Another benefit of design-build contracts is that they offer a "best value" selection process: ODOT evaluates proposals for quality before cost estimates are discussed. This process encourages proposers to exceed the minimum requirements while still keeping costs as low as possible.
For the first time, ODOT used the construction manager/general contractor method to deliver the Interstate 5 Willamette River Bridge project in Eugene-Springfield, the largest in the bridge program in both size and investment. As in design-build, once ODOT selected the designer and builder, the two companies partnered to design and build the bridge - but in constant collaboration with the agency, as the owner. The primary advantages to ODOT of CM/GC are the accelerated schedule, which is enabled by design packages completed by the designer and contractor, increased feedback from all partners, and the ability to weigh cost versus risk real time as work proceeds. By judiciously assuming more of the risk, the agency saves taxpayers money as various aspects of construction are negotiated as work progresses.