In addition to 100- and 140-ton (91 and 127 t) cranes, Max J. Kuney Co. is using five hydro cranes in the 40- to 50-ton (36 to 45 t) range on the project, primarily Link-Belt.
The longest concrete slab, beam and girder-style structure in Oregon is being replaced by a new structure that meets modern standards.
The Martin Luther King, Jr., Boulevard viaduct was built in Portland in 1936 by Hoffman Construction Company at the cost of half a million dollars. The structure sits on the edge of a wetland area that had been filled with debris, as deep as 66 ft. (20 m) in places, from a nearby sawmill.
“That got covered over with miscellaneous dirt fill, and that’s what they came through in the 30s and drove piling through,” said John D. Smith, the Oregon Department of Transportation’s (ODOT) assistant project manager of the viaduct replacement project.
That worked fine for the amount of traffic in the 30s, but the design couldn’t handle the coming years’ increase in frequency, size and weight of vehicles. The viaduct, which serves southbound traffic on Highway 99E, a major shipping and commuter route, began to settle.
About ten years ago, a distinct dip in the bridge developed where a bent had settled 6 to 7-in. (15 to 17 cm). Truck traffic was detoured around the structure and ODOT started making plans to replace it and a 1965 sister structure that carries 99E’s northbound traffic.
The design process was drawn out, for a couple of reasons. Because the city of Portland plans to take ownership of the new bridge when it is completed, the city government has been involved with the design.
In addition, the bridge is designated as a “lifeline structure,” meaning that it must be designed to survive disasters, specifically high-magnitude earthquakes, so that emergency vehicles and suppliers can travel the highway as they respond to the crisis. The criteria required to plan for that contingency kept changing, affecting the in-progress bridge design.
Other challenges include the fact that the construction site is restricted to a very confined area; in some places, construction is happening less than 5 ft. (1.5 m) away from existing buildings. Concerned about impacting local businesses, officials opted not to purchase and demolish nearby buildings to accommodate construction.
To account for the tight quarters, combined with the fact that ODOT was required to maintain two lanes of traffic in each direction at all times during the construction process, the project was “sliced and diced,” as Smith puts it, into six stages.
“We’re in Stage 3 now, which involves a lot of moving traffic around and whatnot to build bridges,” said Tobin Smith, project manager of the contractor, Max J. Kuney Co. of Spokane, Wash. “There are two temporary bridges we had to build that traffic is running on right now.”
Tobin Smith said that there’s “a little of everything” going on now at the site, from pouring facing for MSE walls to driving piles, from pouring columns to forming up cross beams. The contractor has an office staff of seven stationed in Portland, plus Smith and an assistant, as well as crews ranging from 35 to 50 people.
Max J. Kuney Co. started onsite March 2007. The first two stages took more than two years to complete; work on Stage 3 began July of this year and should run through May. Originally, the entire project was scheduled for completion in May 2010, but unexpected soil conditions called for a design change that added months to the timeline. The current completion date is April 2011, with some landscaping work carrying over for some months after that.
When it is finished, the $75-million project will have entirely replaced both the MLK and Grand Avenue viaducts with new structures boasting sidewalks, wider shoulders and medians, as well as improvements to pedestrian ramps. The overall footprint will remain mostly the same.
At this stage, crews have torn down the old northbound bridge, the one built in 1965, and are currently building the new northbound structure. For now, northbound traffic is directed along the newly built structure that will carry southbound traffic in the permanent configuration. Presently, southbound traffic is using a temporary structure.
In addition to 100- and 140-ton (91 and 127 t) cranes, Max J. Kuney Co. is using five hydro cranes in the 40- to 50-ton (36 to 45 t) range on the project, primarily Link-Belt. The contractor is employing more hydro cranes than normal because of the tight quarters. “We needed something more mobile” than lattice cranes, said Tobin Smith.
While work proceeds on the job site, John Smith is in communication with both the city of Portland and TriMet, the region’s transit service. Within the next couple of years, both organizations are starting projects that will overlap the site of the viaduct replacement project. John Smith said: “We’ve been coordinating…so we don’t build something and they come in a year after we’re done and tear it out.”
“I pay taxes too and I hate to see my money thrown away,” he added.