An aerial view of the work bridge with cranes in place.
As spring fully unfolds in Portland, Ore., construction crews are starting their third and final season at work improving the state’s most congested section of Interstate 5.
The I-5 Delta Park – Victory Boulevard to Lombard Street project widens a 1.2-mi. (1.9 km) section of interstate that is one of the area’s worst bottlenecks. Prior to construction, traffic traveling south from Vancouver, Wash., to Portland had to go from three lanes to two before crossing the Columbia Slough. The Delta Park to Lombard project widens I-5 southbound to three lanes to eliminate that bottleneck.
Contractor Hamilton Construction of Springfield, Ore., started work on the $49-million project almost two years ago. The first phase of the project focused on widening I-5 southbound, which required constructing a new southbound entrance ramp bridge at Columbia Boulevard.
The new ramp bridge, which is two lanes wide and approximately 600 ft. (183 m) long, is unique in that its northern abutment sits on top of an MSE retaining wall that is 50 ft. (15 m) tall at the highest point. This design was chosen because right of way issues made it unfeasible to buy adjacent properties and do a fill.
The 1,600-ft.-long (487 m) wall is made of a wire-faced, manufactured system called Terratrel, made by Reinforced Earth Company. It was built in sections to accommodate the project’s schedule, with the highest part of the bridge being built first.
The project’s first phase also included widening an existing bridge over the Columbia Slough, which required the contractor to build four work bridges in the slough.
“In this case, we had an existing bridge we were trying to widen where we had to match span lengths… we had to build in water to match what was already in water,” said Oregon Department of Transportation spokesman Adam Markell.
That turned out to be a challenge for the contractor, which had to build seven coffer dams in order to extend the bridge’s existing pier-style footings. The coffer dams were unusual in that they were three-sided.
“The fourth side didn’t connect… it had to butt up against the existing concrete wall and [the contractor] had to try and seal that interface as best they could,” Markell said.
The contractor built two of the coffer dams in 2008, experimenting with a combination of steel plates, concrete anchors, sandbags, welding and expanding foam to find the best way to seal the interface. The contractor “had a hard time” with the first two, said Markell, but by the second construction season the learning curve was working in its favor.
An added complication during the bridge-widening process was an in-water work window of just three months, imposed for environmental reasons.
“The contractor had to work multiple shifts, sometimes around the clock,” said Markell. “It was not easy.”
Cranes were prevalent on the job site during the first year of construction. Markell recalled touring the project and counting as many as seven cranes, including two large crawler cranes — one of which was an 80-ton (72.5 t) Manitowoc — and at least two 50-ton (45 t), rubber-tire hydraulic cranes. In addition, a 150-ton (136 t) crane was rented from local company Campbell Crane & Rigging Service in order to hang the steel girders for the new ramp bridge.
The new ramp bridge features drilled shaft foundations that reach eight ft (2.4 m) in diameter and go 120-ft. (36.5 m) deep. Utah-based subcontractor Becho Inc. used an oscillator and a 150-ton Liebherr crane to install the steel casing in 20-ft. (6 m) sections and then to remove it as the concrete was poured.
The second construction season focused on widening I-5 northbound, including two northbound bridges: the Columbia Boulevard bridge and Columbia Slough bridge. Crews also worked on rebuilding parts of the northbound off-ramps for Columbia and Victory boulevards.
More than 30 subcontractors have been brought in for the project. One of the larger jobs went to K & E Excavating, based in Salem, Ore., which did approximately $10 million worth of earthwork. Markell says: “They had a lot of equipment out there. At one time, I counted five different excavators and a couple of off-road dump trucks… and that was just at one fill.”
The project’s final construction season is being spent resurfacing the bridge decks in the center of the freeway. A 7 ft. (2m) wide, cold plane micro-milling machine is being used for removal; a Bid-Well concrete paving machine will resurface the new concrete. That work is scheduled for completion in June.
Asphalt work on the full length of the project should begin in July. Striping, landscaping, fencing and other finishing touches will happen this fall. The contractor is slightly ahead of schedule and may wrap up before the original November completion date.
“I think the contractor truly understands ODOT’s commitment to getting this project finished on time… This is the worst bottleneck in the region. We’ve made promises and commitments that this will be opened up to three lanes at the end of this season. The contractor understands how important that is,” Markell said.