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Oregon Demonstration Project: Alternate Project Delivery And Accelerated Bridge Construction On OR 38, Drain To Elkton
Removal and Replacement of or 38 Crossings
Crossing 1 Over Elk creek at MP 36.39, Near Elkton
The old bridge was a two-lane facility built in 1931. The 400-ft-long, six-span, reinforced concrete deck girder (RCDG) structure with steel truss served as the entrance to the town of Elkton (Figure 6). Figure 7 and Figure 8 depict the old and newly proposed typical sections for crossing 1.
Figure 6. Old bridge over Elk Creek near Elkton (crossing 1).
The new four-lane, 420-ft-long, three-span bridge was constructed next to the old structure using precast concrete deck girders, precast columns, and bent caps. Phasing of construction allowed traffic to continue using the old structure while the northern half of the new bridge and roadway approaches were being built. Traffic was then diverted to this portion of the new bridge and work on the southern half of the bridge commenced.
Figure 9 shows the completed northern portion of the bridge and the substructures of the southern portion. The old bridge was demolished and removed while work on the southern half of the new bridge and new roadway approaches continued.
Concurrent with the construction of the southern half of the new bridge, improvements were also made to the intersection of OR 38 and OR 138. This intersection is located at the edge of Elkton immediately west of the bridge. The contractor used drilled shafts to support the bents, eliminating the need for spread footings. Spread footings require cofferdams, which would have added cost and adversely impacted the environment.
The approaches to the bridge on both the east and west sides were stabilized using a stepped-down geogrid reinforcement system with well-graded aggregate (Figure 10).
Figure 7. Crossing 1 old typical section.
Figure 8. Crossing 1 proposed typical section.
Figure 9. Crossing 1 looking east.
Figure 10. View of stepped-down geogrid system at crossing 1.
Crossing 2 Over Elk Creek at MP 38.76
The contractor chose to change the alignment of OR 38 by building the entire bridge offline with minimal interference to traffic flow. The old bridge, built in 1932, was a 290-ft-long, six-span, RCDG structure. The old structure was replaced with a three-span bridge constructed with precast concrete deck girders on a new alignment to improve the permanent horizontal curvature of the roadway.
During construction, travelers continued to use the old bridge while the new bridge on a new alignment was being constructed next to the old bridge (Figure 13). Upon completion, traffic was shifted to the new structure and the old bridge and roadway approaches were dismantled and removed.
Figure 11 and Figure 12 depict old and proposed typical sections for crossing 2.
Figure 11. Crossing 2 old typical section.
Figure 12. Crossing 2 proposed typical section.
Figure 13. View of old and new crossing 2 looking west.
Crossings 3 and 4 Over Elk Creek at East and West of Elk Creek Tunnel at MP 39.64 and 39.97
The old crossings 3 and 4 were built in 1932 and 1931, respectively. Crossing 3 was a 340-ftlong, six-span, RCDG structure with steel truss residing at the western entrance of the Elk Creek Tunnel. The crossing 4 structure was a 240-ft-long, five-span, RCDG bridge with steel truss located at the eastern entrance of the Elk Creek Tunnel.
Replacement of crossings 3 and 4 presented ODOT with extremely challenging tasks because of their close proximity to tunnel entrances and the presence of Elk Creek.
Construction of detour bridges at this location was impossible since these bridges were only a short distance (50 to 70 ft) from either end of the Elk Creek Tunnel. With these severe limitations, the only viable alternative available was to remove and replace the bridges using HSS, an innovative rapid bridge replacement technique.
In general, rapid removal and replacement of bridges using HSS involves four stages. Figure 14 shows the conceptualization of the stages. The stages are as follows:
Figure 14. Conceptualized stages of rapid bridge removal using HSS.
The new bridge at the west portal of the tunnel (crossing 3) is a three-span structure constructed with steel deck girders with the overall length of 320 ft. The new bridge at the east portal of the tunnel is a two-span, 220-ft-long bridge constructed using precast concrete deck girders. Both new bridges were constructed on temporary support systems next to the old structures to permit continued use of the old bridges with no impact on traffic movement.
Concurrent with the construction of the new superstructures, substructures were constructed underneath the old bridge, which included installation of drilled-shaft foundations, columns, and bent caps. During a weekend road closure, each new bridge was lifted and translated sideways to its final destination by HSS.
HSS is equipped with giant hydraulic jacks mounted on a sliding rail capable of lifting massive weights. These hydraulic jacks are pushed on the rails by hydraulic pumps to translate bridges from one point to another. Figure 15 and Figure 16 depict the old and proposed typical sections for crossing 3. The old and proposed typical sections for crossing 4 are shown in Figure 17 and Figure 18. Figure 19 illustrates the entire HSS.
Figure 15. Crossing 3 old typical section.
Figure 16. Crossing 3 proposed typical section.
Figure 17. Crossing 4 old typical section.
Figure 18. Crossing 4 proposed typical section.
Figure 19. View of a complete hydraulic sliding system, including hydraulic jacks, hydraulic pumps, and the railing system.
Traffic impact was confined to only 2 weekends for both bridges instead of 2 years under a standard practice staged construction. To ensure timely replacement of these bridges, incentive and disincentive provisions were included in the construction contract. The contractor substantially exceeded the criteria set by ODOT and received the maximum incentive valued at $600,000 ($20,000 for each day not exceeding 30 days).
Figure 20 through Figure 23 illustrates the entire process involved in rapid removal and replacement of crossings 3 and 4. This process required months of preparation, but significantly minimized the adverse traffic impacts on neighboring residents, businesses, and the traveling public.
ODOT closed OR 38 between Elkton and Drain on two separate Fridays in preparation for the removal and replacement of crossings 3 and 4. The surrounding communities were informed of the upcoming construction activities and lane closures through signs, news media, and the dedicated Web site. A detour was put in place during this 2-day closure. Motorists heading west from Interstate 5 to Reedsport were advised to take exit 136 (Sutherlin) and follow OR 138 to Elkton. Motorists traveling east from Reedsport to I-5 were advised to take OR 138 from Elkton and follow it to I-5. To facilitate the removal of the old superstructure, some preliminary work had to be performed on the surface, including sawing and removal of the old asphalt overlay and demolition and removal of the bridge railings and approach slabs. This work was done on Friday evening after the 8 p.m. closure of OR 38 (Figure 20).
Figure 20. Demolition and dismantling of end panels.
On Saturday, the old superstructure was lifted and slid onto its temporary support to make room for the new superstructure. Figure 21 shows the old and the new superstructures and substructures side by side for crossing 3.
Figure 22 shows the new superstructure of crossing 3 after it was translated onto its final destination, including the prefabricated approach panels, the newly paved approach roadway, and the precast wing walls. The entire removal and replacement process took about 4 hours. The remaining time on Saturday and Sunday was spent on work on the approaches to the structures, which included the following:
Early Monday morning, the bridge was opened to traffic, as shown in Figure 23.
Figure 21. View of old and new superstructures at crossing 3.
Figure 22. Replacement of superstructure and end panels at crossing 3.
Figure 23. Completed crossing 4 after opening to traffic.
Crossing 5 Over Hardscrabble Creek at MP 48.00
The old bridge, built in 1929, was a 90-ft-long, three-span, RCDG structure. This bridge was in very poor condition with delaminated concrete components and exposed corroded reinforcement. Because of extremely tight right-of-way clearances and the site's proximity to Elk Creek, ODOT stipulated replacing the bridge within a 180-day construction period. Typical sections for the old Incentive and disincentive clauses ($4,500 per day for a maximum of 30 days) were included for the replacement of this bridge to encourage accelerated construction and minimize the duration of traffic disruption. ODOT awarded the contractor an incentive of $135,000 (maximum incentive) for rapid removal and replacement of crossing 5.
Figure 24. Crossing 5 old typical section
Figure 25. Crossing 5 proposed typical section.
The proposed new structure consisted of a single-span bridge constructed with precast concrete deck members. To facilitate bridge construction and modification of the existing roadway alignment, a temporary single-lane detour bridge was erected and used for 6 weeks (Figure 26). Travelers and neighboring residents and businesses were informed of the upcoming detour by signs and through the public outreach program.
The total distance of this single-lane detour was only 300 ft. Detour use was controlled by flaggers at each end of the detour bridge 24 hours a day, 7 days a week. Traffic control signs were erected, flagger stations were illuminated for nighttime operations, and traffic speed through the work zone was reduced to 20 mi/h for the duration. Figure 27 shows completed crossing 5. No incidents were reported during the traffic control operation.
Figure 26. View of the temporary and old bridges looking east.
At the conclusion of the 6-week single-lane detour, the new bridge was opened to traffic in both directions and the detour bridge was dismantled and removed (Figure 27).
Figure 27. View of completed crossing 5 and dismantling of the detour bridge.