Twin bridges, but not identical

From ODOT-

Soon, you will see the piers and foundations poured for the new northbound Interstate 5 Willamette River Bridge.



When finished, the northbound span will appear identical to the southbound bridge, but up close, you'll see a few significant differences.



What's the same:

The main arch spans crossing the river will be identical and both bridges touch down only once in the river, in stark contrast to the old bridge's numerous piers.



What's different:

The new bridges will be noticeably different on the south end where they connect to the roadway.



The southbound bridge has nine spans and a total length of 1,759 feet. The northbound bridge will have 10 spans and a total length of 1,985 feet. the additional northbound span will pass over the I-5 northbound off-ramp to Franklin Boulevard.



For the majority of their length, the two bridges will have a gap of 16 feet between them. But the gap will narrow as the two bridges meet the roadway at the south end.



Because of the small difference in the twin bridges, we save time and money by using the same design on both and incorporating lessons learned from building the first into the second bridge.

No Climbing of the Arches

From ODOT-

The graceful appearance of the arches on the new southbound Willamette River Bridge is in stark contrast to the multiple columns still remaining from the detour bridge. The remaining columns will be removed during demolition of the detour bridge, scheduled to begin in October. Then, the advantage of the single touchdown point of the arches in the river will become more recognizable.

The arch design decreases the impact of multiple bridge columns on the river environment, but creates a new safety issue. The old bridge’s support columns were vertical, smooth and almost impossible for a person to scale. The gentle slope of the new arches now provides an inviting temptation for daredevils to climb over the river from either bank.

When passing by the new bridge on the nearby paths, you might notice what we have done to discourage climbing on the arches. Our contractor crews built tall walls between the arch and the adjacent spandrel column to block access. In addition, crews poured a lid on top of each wall to prevent debris from falling into the enclosure created by the walls.

The design of the walls included the use of concrete form liners and are an added enhancement which is intended to blend with the bridge but still provide needed function.

We hope you enjoy the new bridge and the improvements to the surrounding area while respecting these steps taken to ensure everyone’s safety.

Workers built a special anti-access wall to prevent daredevils from climbing the new Willamette River Bridge arches.

Replacing the Temporary Bridge

From ODOT- With all the construction work under way on the new Interstate 5 Willamette River bridges, it’s easy to forget the bridge carrying I-5 traffic since 2004 is temporary.

This fall, when the new southbound bridge is complete, we’ll shift all I-5 traffic onto it, which will allow us to dismantle the temporary bridge clearing the way for construction of the new northbound bridge.

As we closely watch construction of the new arch bridges, I think it’s important to remember why we’re building them.

When ODOT inspected the original I-5 Willamette River bridges in 2002, we discovered structural problems in the aging girders. We quickly put load limits in place that forced heavy haul truck traffic to detour on U.S. 97 through Central Oregon. The long detour increased the cost and time of moving goods in and through Oregon.

While we immediately started planning for new bridges to replace the old, we knew it would take significant amount of time to design and construct a bridge to meet the environmental and seismic standards for permanent bridges with a lifespan of 100 years. That was too long to wait to return heavy truck traffic to I-5 through Eugene-Springfield. Building a temporary bridge became the best interim solution.

We quickly designed a temporary bridge and acquired needed right of way and permits. Our contractor, Hamilton Construction, started work on the temporary bridge in 2003, and it opened to traffic in 2004. The temporary bridge was built using materials and methods that could be quickly installed, but it does not meet all standards required for a permanent bridge with 100-year lifespan.

The temporary bridge has carried traffic for more than six years. During that time heavy freight has moved easily on I-5. Truckers, and the consumers of the goods they transport, have avoided the economic impacts of a costly detour.

We expect the new bridges to be complete in 2013, almost a decade after the temporary bridge opened. By the time both new bridges are open to traffic, Oregonians will see a good return on their investment in the temporary bridge. In addition, material from the temporary bridge will be reused or recycled, and the right of way used for the temporary bridge will be returned to its natural state.

When the work is done, our goal is to leave the project area in far better shape than we found it.

National Science Foundation and the Willamette River Bridge

From ODOT-

Earlier this week I had the privilege of escorting a film crew associated with Oregon State University, the Harvard-Smithsonian Center for Astrophysics Science and the National Science Foundation around the WRB project. The end product is a NSF piece for classroom use, aimed at students who are having a harder time grasping math concepts as they apply to real world.

This bridge project attracted them because of the unique arches that will support the new bridges. The arches, which may appear decorative to the casual observer, are actually highly technical, carefully engineered supports based on a modern update of construction principles used in the Roman Empire. The process to construct the arches requires a series of complex steps executed perfectly in concert- from the wooden arch structure and rebar cages that will frame poured concrete to the casting of the crown used to support the weight of both sides holding the arches together and providing the necessary strength for the overall bridge structure.

In addition to interviewing the project manager and a couple of engineers, the crew also interviewed one of the carpenter apprentice workers. She explained how she uses fundamental physics and math everyday in her job on the construction site.

Once the video and supporting curricular materials are completed, the NSF will make the materials available for free download through an associated website and catalogued by the NSF National Science Digital Library.