Eugene, Oregon, the home of the University of Oregon, is a thriving town. One of the main thoroughfares leading into downtown Eugene is I-105. Because of the high usage of the roadway, the I-105 Willamette River Connectors projectwas conceived to preserve and improve the safety of the road.

The project consists of three phases. While each phase will improve safety and increase preservation, there are many differences.

Filling in a Bridge 

Phase one began in the October of 2018 and concluded in January of 2019. It involved the removal of an obsolete bridge, which is a section of I-105. When built, the idea was that the 300-foot bridge, which was 20 feet off the ground, would go over a highway that was ultimately never constructed. Now, that bridge needs repairs. Since it is not needed, the bridge was removed, and fill was added to make the section a regular paved road. The pavement was rebuilt on a pile of dirt, so it would be at the same elevation as the rest of I-105.

The void was filled in under the road prior to removing the bridge to reduce the length of time traffic would be inconvenienced. Lightweight cellular concrete – which goes in like water and is made up of cement, water, and a foaming agent – was pumped into the area. The concrete ultimately hardens in about a day. 

“We used lightweight concrete because it helps to create a settlement, does not overload the ground beneath it, and uses less environmental resources,” says Steve Templin, an Oregon Department of Transportation (ODOT) Resident Engineer. Templin’s role is to take projects after the design phase and manage them through construction until they are accepted and administer the construction contracts.

Joint Replacement and Vital Upgrades

Phase two focused on the rehabilitating of another bridge along I-105. Known to ODOT as the torso, wings, and legs, the half-mile bridge has multiple offramps thatlead to downtown Eugene. The aging structure required repair as it had a significant amount of joint failure.

The bridge being focused on in phase three is over 900 feet, was built in the 1960’s, and spans the Willamette River. Elements of the project include: installing guardrails that meet current crash standards, paving, seismic upgrades, and replacing bridge joints.

“The bridge is showing signs of wear particularly on the deck,” says Templin. The wear includes significant concrete delamination and exposed rebar from the top of the bridge. There are 2-inch potholes due to the fatiguing and wearing out of the bridge joints. Regarding the guardrails, Templin says, “The old ones were not big enough to hold to up to the larger heavier trucks that are being manufactured today.”

Lessons Learned

Just how busy is I-105? Well, average daily traffic in the areas being repaired is 60,000 cars per day. Minimizing closures and managing commuter expectations has been one of the major challenges of the project. “People are accustomed to having us do work in the middle of night,” says Templin. “However, this project required continuous closures to perform the work.”

ODOT feels it was not as prepared as it could have been for the amount of traffic and pushback that occurred during the first phase. The department took it as a challenge to do a better job. They responded by redesigning elements of the project to ensure it would occur as quickly as possible. 

ODOT went through the design meticulously as it sought ways to speed up the work. “We redesigned several features so that while the end product is not different, the building of it was,” says Templin.  “We were able to strengthen and utilize more of the existing structure and only rebuild or replace smaller sections which resulted in more room to accommodate traffic during construction and reduce closure times several weeks.”

The four ramps, leading to downtown Eugene, were expected to be closed from six to eight weeks per ramp. However, ODOT was able to expedite the process so only two of the ramps were completely closes and for just four weeks a piece.

Finally, a significant PR campaign was initiated. Besides working with the communities, the public relations campaign pushed for commuters to consider alternative transportation options such as biking and public transportation. In addition, the dates when construction was set to take place were well advertised. The schedule was altered so that major closures occurred when the University of Oregon and local schools were not in session, traffic is lightest, and the weather is the nicest.

Project Acceleration Saves Money

The I-105 Willamette River Connectors project has a construction budget of $18 million. Funding is coming primarily from the federal government via the federal gas tax while the state is also providing some financing. Due to the initial traffic problems, extra money was provided to help mitigate traffic congestion.  Cameras were added to assist the City of Eugene to monitorandtime signals quickly on the most used alternate route.  But, as a result of the redesign efforts, much of the costs were mitigated. 

“We didn’t need use all of the extra money and actually had a net saving of nearly half a million dollars due to the reduced scope of work and acceleration that came as a result of the redesign effort,” says Templin.

Bridge rails will be on each of the new structures. They are being completed via a slip form. Wet concrete is dumped into the machine that produces the bridge rail in its required form. A minimal amount of hand work is needed before it can be set up and dries within a couple of days. “Using slip form has saved labor and time,” says Templin.

As noted above, the project began in October 2018. It’s expected to be complete in the summer 2020. Upon completion the I-105 Willamette River Connectors project will expand the life of the road and increase safety. Those Eugene commuters who utilize the road should enjoy a smooth ride for years to come.