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Oregon Demonstration Project: Alternate Project Delivery And Accelerated Bridge Construction On OR 38, Drain To Elkton
OR 38 is a mountainous two-lane route with large elevation changes that passes across Oregon's coastal range. Oregon's HfL project consisted of removing and replacing five bridges on an 11mi stretch of OR 38 between the towns of Drain and Elkton. All five bridges (Figure 1) were built in the late 1920s and early 1930s and were approaching the end of their useful life. Although all of the bridges identified for replacement had challenging site conditions, two (crossings 3 and 4) stood out for their exceptionally difficult topographic and environmental conditions. Crossings 3 and 4, located at mileposts (MP) 39.64 and 39.97, respectively, are situated at each end of the Elk Creek Tunnel in Elk Creek Tunnel State Park.
Figure 1. OR 38 bridge replacement project locations.
At the east end of the tunnel, only 30 ft separated the tunnel portal and the bridge abutment of crossing 4. At the tunnel's west end, that separation was only 70 ft for crossing 3. For staged construction, the transitions from the tunnel to a temporary roadway during construction would have been nearly impossible. To add to the site complexity, the tunnel width is only 25 ft, thereby restricting traffic lane shifts to accommodate wide loads. OR 38 is routinely and heavily used by logging trucks and commercial vehicles. Also, these two bridges fell within the northern spotted owl nesting and roosting habitat. As a result, replacement of these bridges required the use of construction activities that did not violate established noise standards between March 1 and July 7 of each year.
The project's overall construction zone extends about 11.5 mi along OR 38 from MP 36.39 (the first crossing of Elk Creek next to Elkton) to MP 48.00 (Hardscrabble Creek). This stretch of OR 38 is posted with speed limits between 35 and 55 miles per hour (mi/h), depending on location. In 2004 average daily traffic (ADT) for the route ranged from 3,200 to 4,400 vehicles, with a projected ADT increase of 20 percent by 2020. The current percentage of truck traffic is estimated at 23 percent of ADT.
ODOT included many innovative, proven technologies and techniques to accelerate replacement of the five bridges, address the many environmental issues associated with the project, and minimize inconvenience to neighboring residents, businesses, and freight carriers. For the most part, ODOT's goals were to maintain two lanes of free-flowing traffic throughout the construction zone, minimize traffic interruptions and queue lengths, and, most important, improve safety and quality and achieve user satisfaction. The innovative features and accelerated elements of the ODOT HfL project included the following:
Each of these innovative elements is described in the following subsections.
Innovative Public Outreach Program
A critical element of ODOT's project was to promote and maintain a cordial partnership with local communities and transportation stakeholders that went beyond conventional public meetings. Long before any heavy equipment or construction crews arrived on the jobsite, ODOT and its public involvement team communicated how the project would affect the local community. Generally speaking, ODOT's communication with the community and stakeholders included the following:
An innovative component of the public information and outreach program was a schools-based outreach program. Under this program students were provided with an opportunity to develop designs for the pylons surrounding one of the bridges. They did this after consulting with community members on what symbols they thought best reflect Elkton. Heading this effort was the project coordinator, Lois Cohen, who said, "We decided from the outset that we wanted to have an exceptional public involvement program.
The primary communities affected by the bridge work were the towns of Drain, Elkton, and Reedsport. For each community, Cohen arranged an outreach program through the local schools. At Reedsport's middle school, students built habitats for bats that will be placed under two of the bridges (Figure 2).
Figure 2. Habitat for bats by Reedsport students.
Figure 3. Gumdrop bridge.
In Drain, elementary school children collaborated on building bridges with gumdrops, saltines, and toothpicks (Figure 3). In Elkton, high school students got the opportunity to design decorative pylons to be placed at all four corners of the Elkton Bridge (crossing 1) with different carved symbols at the top of each pylon reflecting Oregon wildlife. These included the osprey, elk, salmon, and monarch butterfly (Figure 4).
Figure 4. Symbols on the pylons designed by students.
Design-Build Method of Project Delivery
One of the major factors in expediting the OR 38 project was to combine the replacement of all five bridges into a single contract using the D-B method of project delivery. D-B contracting is an alternative to the traditional design-bid-build (D-B-B) system, which in recent years has gained a lot of momentum at the national level. Many states either use D-B on selected contracts or implement this method of awarding contracts as a standard practice. The D-B procurement process combines the design and construction phases of a project into a single contract and allows for overlapping of some design and construction. In essence, construction can begin on parts of the project before design for the total project has been completed. The goals are to reduce project costs, shorten the overall project schedule, and construct a quality project.
ODOT's D-B contract required the successful contractor to use accelerated construction techniques to minimize the duration of construction, reduce vehicle delays, provide a safer environment for the traveling public and workers, and keep the community abreast of all major activities.
Figure 5 is a schematic comparing D-B and D-B-B.
Figure 5. Design-build versus design-bid-build. (Source: Dr. Keith Molenaar)
One of the main factors responsible for accelerating the ODOT's OR 38 project was the construction of the superstructures for two bridges (crossings 3 and 4) off-site, next to the old bridges. These two crossings, located at the east and west end of the Elk Creek Tunnel in Elk Creek State Park, presented extremely challenging site conditions. At the east end of the tunnel, only 30 ft separated the tunnel portal and the bridge abutment.
The contractor's approach was to build the two new superstructures on temporary piers next to the old structures and slide them into their final position during a weekend road closure.
The benefits of constructing the superstructures of crossings 3 and 4 offsite included the following:
Construction of Substructures Without Interfering With Traffic Flow
Concurrent with the construction of the superstructures of crossings 3 and 4, substructures were constructed underneath the old bridges with absolutely no impact on OR 38 traffic. The construction of the substructures consisted of building drilled shaft foundations to support the cast-in-place columns and pier caps. The precast components included the wing walls, sleeper slabs, and approach concrete pavement panels.
Context-Sensitive and Sustainable Solutions
An essential consideration in developing and constructing highway and bridge projects in Oregon is satisfying CS3 requirements. CS3 is an innovative decision-making tool that combines the old context-sensitive design philosophy with the concept of sustainability, an approach unique to ODOT. The primary goals of Oregon's CS3 program are the following:
Overall, CS3 puts communities and stakeholders at the heart of decision-making . Listening to and responding to community and stakeholder needs are essential components in developing and completing transportation projects under the CS3process. On this project, the CS3approach resulted in minimizing environmental impacts and development of a systematic permitting vehicle that streamlined the time-consuming environmental permitting process.
According to ODOT, "through this process, we have been able to maintain our environmental stewardship while improving the program delivery process and outcomes."
Rapid Bridge Replacement Technique Using Hydraulic Sliding System
Crossings 3 and 4 were successfully removed and replaced during a weekend closure using HSS rapid bridge replacement technology. In this system of bridge relocation, hydraulic jacks mounted on a sliding rail lift the new superstructures and hydraulic pumps slide them into their final position. HHS was also used to slide the old superstructure onto temporary supports before sliding in the new superstructure. Using this method, traffic impact was dramatically reduced to 1 weekend for each crossing instead of 2 years under the standard staged construction approach. In addition, the use of HSS substantially improved the safety of the traveling public and workers in the work zone. The contractor was awarded a maximum incentive of $600,000 for crossings 3 and 4.
Use of Temporary Bridge
To facilitate the removal and reconstruction of the bridge over Hardscrabble Creek (crossing 5) at MP 48.00, a temporary single-lane detour was erected and used for about 6 weeks. The length of this detour was only 300 ft. Flaggers controlled traffic at this location 24 hours a day, 7 days a week. The new bridge was widened to 24 ft plus shoulders on improved alignment and with safer TL-4 bridge rails modified to improve aesthetic appearance.
By using the temporary bridge, the contractor was able to complete the reconstruction of crossing 5 in less than 6 weeks instead of the originally scheduled 6 months. As a result, ODOT awarded the contractor an incentive of $135,000 ($4,500 per day for a maximum of 30 days) for rapid removal and replacement of crossing 5.
Use of Prefabricated Bridge Components
The prefabricated components of OR 38 included sleeper slabs, approach pavement panels, wing walls (crossings 3 and 4), and precast concrete deck girders. All of the precast components were fabricated at the contractor's yard and transported to the project site for installation.